[Federal Register Volume 80, Number 126 (Wednesday, July 1, 2015)]
[Proposed Rules]
[Pages 37758-37806]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-15192]
[[Page 37757]]
Vol. 80
Wednesday,
No. 126
July 1, 2015
Part II
Environmental Protection Agency
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40 CFR Parts 87 and 1068
Proposed Finding That Greenhouse Gas Emissions From Aircraft Cause or
Contribute to Air Pollution That May Reasonably Be Anticipated To
Endanger Public Health and Welfare and Advance Notice of Proposed
Rulemaking; Proposed Rule
Federal Register / Vol. 80 , No. 126 / Wednesday, July 1, 2015 /
Proposed Rules
[[Page 37758]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 87 and 1068
[EPA-HQ-OAR-2014-0828; FRL 9924-06-OAR]
RIN 2060-AS31
Proposed Finding That Greenhouse Gas Emissions From Aircraft
Cause or Contribute to Air Pollution That May Reasonably Be Anticipated
To Endanger Public Health and Welfare and Advance Notice of Proposed
Rulemaking
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule and advance notice of proposed rulemaking.
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SUMMARY: In this action, the Administrator is proposing to determine
that greenhouse gas concentrations in the atmosphere endanger the
public health and welfare of current and future generations within the
meaning of section 231(a) of the Clean Air Act. She proposes to make
this finding specifically with respect to the same six well-mixed
greenhouse gases (GHGs)--carbon dioxide, methane, nitrous oxide,
hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride--that
together were defined as the air pollution in the 2009 Endangerment
Finding under section 202(a) of the Clean Air Act and that together
constitute the primary cause of the climate change problem. The
Administrator is also proposing to find that greenhouse gas emissions
from certain classes of engines used in aircraft are contributing to
air pollution--the mix of greenhouse gases in the atmosphere--that
endangers public health and welfare under section 231(a) of the Clean
Air Act. Concurrent with these proposed findings, the EPA is issuing an
Advance Notice of Proposed Rulemaking to provide an overview of and
seek input on a variety of issues related to setting an international
CO2 standard for aircraft at the International Civil
Aviation Organization (ICAO), ICAO's progress in establishing global
aircraft standards that achieve meaningful reductions in CO2
emissions, and (provided the EPA promulgates final endangerment and
cause and contribute findings for aircraft engine GHG emissions) the
potential use of section 231 of the Clean Air Act to adopt and
implement corresponding aircraft engine GHG emission standards
domestically, ensuring transparency and the opportunity for public
comment.
DATES: Comments. Comments must be received on or before August 31,
2015.
Public Hearing. The EPA will hold a public hearing on August 11,
2015 in Washington, DC, at the William Jefferson Clinton East Building,
Room 1153, 101 Constitution Avenue NW., Washington, DC 20004. If no one
contacts the EPA requesting to speak at the hearing for this proposal
by July 13, 2015 the public hearing will not take place and will be
cancelled with no further notice. Speakers should contact Ms. JoNell
Iffland (see FOR FURTHER INFORMATION CONTACT) to request to speak at
the hearing. The last day to pre-register in advance to speak at the
hearing will be August 6, 2015. The hearing will start at 10:00 a.m.
local time and continue until everyone has had a chance to speak.
Requests to speak will be taken the day of the hearing at the hearing
registration desk, although preferences on speaking times may not be
able to be fulfilled. If you require the service of a translator or
special accommodations such as audio description, please let us know at
the time of registration. For further information on the public hearing
or to register to speak at the hearing, please see section I.B below or
go to http://www.epa.gov/otaq/aviation.htm.
ADDRESSES: Comments. Submit your comments, identified by Docket ID No.
EPA-HQ-OAR-2014-0828, by one of the following methods:
Online: www.regulations.gov Follow the on-line
instructions for submitting comments.
Email: [email protected] Attention Docket ID
No. EPA-HQ-OAR-2014-0828.
Fax: (202) 566-9744, Attention Docket ID No. EPA-HQ-OAR-
2014-0828.
Mail: U.S. Postal Service, send comments to Air and
Radiation Docket and Information Center, Environmental Protection
Agency, Mail Code: 28221T, 1200 Pennsylvania Ave. NW., Washington, DC
20460. Attention Docket ID No. EPA-HQ-OAR-2014-0828.
Hand Delivery: U.S. Environmental Protection Agency, EPA
West, EPA Docket Center, EPA West Building, Room 3334, 1301
Constitution Ave. NW., Washington, DC 20004. Attention Docket ID No.
EPA-HQ-OAR-2014-0828. Such deliveries are only accepted during the
Docket's normal hours of operation, and special arrangements should be
made for deliveries of boxed information.
Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2014-0828. See section I.B on ``Public Participation'' for more
information about submitting written comments. The EPA's policy is that
all comments received will be included in the public docket without
change and may be made available online at http://www.regulations.gov,
including any personal information provided, unless the comment
includes information claimed to be confidential business information
(CBI) or other information whose disclosure is restricted by statute.
Do not submit information that you consider to be CBI or otherwise
protected through http://www.regulations.gov or email. The http://www.regulations.gov Web site is an ``anonymous access'' system, which
means the EPA will not know your identity or contact information unless
you provide it in the body of your comment. If you send an email
comment directly to the EPA without going through http://www.regulations.gov, your email address will be automatically captured
and included as part of the comment that is placed in the public docket
and made available on the Internet. If you submit an electronic
comment, the EPA recommends that you include your name and other
contact information in the body of your comment and with any disk or
CD-ROM you submit. If the EPA cannot read your comment due to technical
difficulties and cannot contact you for clarification, the EPA may not
be able to consider your comment. Electronic files should avoid the use
of special characters, or any form of encryption, and be free of any
defects or viruses. For additional information about the EPA's public
docket visit the EPA Docket Center homepage at: http://www.epa.gov/dockets. For additional instructions on submitting comments, go to
section I.B of this document.
Docket. The EPA has established a docket for this rulemaking under
Docket ID No. EPA-HQ-OAR-2014-0828. All documents in the docket are
listed in the www.regulations.gov index. Although listed in the index,
some information is not publicly available, e.g., CBI or other
information whose disclosure is restricted by statute. Certain other
material, such as copyrighted material, is not placed on the Internet
and will be publicly available only in hard copy in the EPA's docket.
Publicly available docket materials are available either electronically
in www.regulations.gov or in hard copy at the Air and Radiation Docket
and Information Center, EPA/DC, EPA WJC West, Room 3334, 1301
Constitution Ave. NW., Washington, DC. The Public Reading Room is open
[[Page 37759]]
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal
holidays. The telephone number for the Public Reading Room is (202)
566-1744, and the telephone number for the Air Docket is (202) 566-
1742.
FOR FURTHER INFORMATION CONTACT: JoNell Iffland, Office of
Transportation and Air Quality, Assessment and Standards Division
(ASD), Environmental Protection Agency, 2000 Traverwood Drive, Ann
Arbor, MI 48105; Telephone number: (734) 214-4454; Fax number: (734)
214-4816; Email address: [email protected]. Please use this
contact information for general questions about this rulemaking, to
request a hearing, to determine if a hearing will be held, and to
register to speak at the hearing, if one is held.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. General Information
A. Does this action apply to me?
B. Public Participation
1. What should I consider as I prepare my comments for the EPA?
2. Public Hearing
C. Did the EPA conduct a peer review before issuing this notice?
D. Children's Environmental Health
E. Environmental Justice
II. Introduction: Overview and Context for This Proposal
A. Summary
B. Background Information Helpful to Understanding This Proposal
1. Greenhouse Gases and Their Effects
2. Statutory Basis for This Proposal
C. The EPA's Responsibilities Under the Clean Air Act
1. The EPA's Regulation of Greenhouse Gases
2. Background on the Aircraft Petition, 2008 ANPR, and D.C.
District Court Decision
D. U.S. Aircraft Regulations and the International Community
1. International Regulations and U.S. Obligations
2. The International Community's Reasons for Addressing Aircraft
GHG Emissions
3. Relationship of the EPA's Proposed Endangerment and Cause or
Contribute Findings to International Aircraft Standards
E. The EPA's Regulation of Aircraft Emissions
III. Legal Framework for This Action
A. Section 231(a)(2)(A)--Endangerment and Cause or Contribute
1. The Statutory Language
2. How the Origin of the Current Statutory Language Informs the
EPA's Interpretation of Section 231(a)(2)(A)
3. Additional Considerations for the Cause or Contribute
Analysis
B. Air Pollutant, Public Health and Welfare
IV. The Proposed Endangerment Finding Under CAA Section 231
A. Scientific Basis of the 2009 Endangerment Finding Under CAA
section 202(a)(1)
1. The Definition of Air Pollution in the 2009 Endangerment
Finding
2. Public Health Impacts Detailed in the 2009 Endangerment
Finding
3. Public Welfare Impacts Detailed in the 2009 Endangerment
Finding
4. The Science Upon Which the Agency Relied
B. Recent Science Further Supports the Administrator's Judgment
That the Six Well-Mixed Greenhouse Gases Endanger Public Health and
Welfare
1. More Recent Evidence That Elevated Atmospheric Concentrations
of the Six Greenhouse Gases Are the Root Cause of Observed Climate
Change
2. More Recent Evidence that Greenhouse Gases Endanger Public
Health
3. More Recent Evidence that Greenhouse Gases Endanger Public
Welfare
4. Consideration of Other Climate Forcers
C. Summary of the Administrator's Proposed Endangerment Finding
Under CAA Section 231
V. The Proposed Cause or Contribute Finding for Greenhouse Gases
Under CAA Section 231
A. The Air Pollutant
1. Proposed Definition of Air Pollutant
2. How the Definition of Air Pollutant in the Endangerment
Determination Affects Section 231 Standards
B. Proposed Cause or Contribute Finding
1. The Administrator's Approach in Making This Proposed Finding
2. Overview of Greenhouse Gas Emissions
3. Proposed Contribution Finding for the Single Air Pollutant
Comprised of the of Six Well-Mixed Greenhouse Gases
4. Additional Considerations
VI. Advance Notice of Proposed Rulemaking: Discussion of Ongoing
International Proceedings To Develop Aircraft CO2
Emissions Standard and Request for Comment
A. Purpose of the International Standard
B. Applicability of the International CO2 Emissions
Standard
C. CAEP Discussion on In-Production Aircraft Applicability
1. Applicability to In-Production Aircraft and Date of
Implementation
2. Reporting Requirement for New In-Production Aircraft
D. Metric System, Applicability, and Certification Requirement
1. CO2 Metric System
2. Applicability
3. Certification requirement
4. Regulating the Entire Aircraft Instead of the Engine
E. Stringency Options
F. Costs, Technology Responses for Stringency Options, and Cost-
Effectiveness Analysis
1. Non-Recurring Costs (Engineering Development Costs)
2. Technology Responses
3. Cost Effectiveness Analysis
G. Request for Comment on the EPA's Domestic Implementation of
International CO2 Standards
VII. Statutory Authority and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Paperwork Reduction Act (PRA)
C. Regulatory Flexibility Act (RFA)
D. UnFunded Mandates Reform Act (UMRA)
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use
I. National Technology Transfer and Advancement Act (NTTAA)
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
K. Determination Under Section 307(d)
VIII. Statutory Provisions and Legal Authority
I. General Information
A. Does this action apply to me?
These proposed findings, if finalized, would trigger new duties
that would apply to the EPA, but would not themselves apply new
requirements to other entities outside the federal government.
Specifically, if the EPA issues final findings that greenhouse gas
emissions from certain classes of engines--those used in certain
aircraft--cause or contribute to air pollution which endangers public
health or welfare, then the EPA would have a duty under section 231 of
the Clean Air Act to promulgate aircraft engine emission standards
applicable to emissions of that air pollutant from those classes of
engines. Only those standards would apply to and have an effect on
other entities outside the federal government. Entities potentially
interested in this proposed action are those that manufacture and sell
aircraft engines and aircraft in the United States. Categories that may
be regulated in a future regulatory action include:
[[Page 37760]]
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Examples of potentially affected
Category NAICS \a\ Code SIC \b\ Code entities
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Industry................................ 3364412 3724 Manufacturers of new aircraft
engines.
Industry................................ 336411 3721 Manufacturers of new aircraft.
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\a\ North American Industry Classification System (NAICS).
\b\ Standard Industrial Classification (SIC) code.
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be interested in this
proposed action. This table lists the types of entities that the EPA is
now aware could potentially have an interest in this proposed action.
If the EPA issues final affirmative findings under section 231(a)
regarding greenhouse gases, the EPA would then be required to undertake
a separate notice and comment rulemaking to issue emission standards
applicable to greenhouse gas emissions from the classes of aircraft
engines that the EPA finds cause or contribute in such a finding, and
the FAA would be required to Prescribe regulations to insure compliance
with these emissions standards pursuant to section 232 of the Clean Air
Act. Other types of entities not listed in the table could also be
interested and potentially affected by subsequent actions at some
future time. If you have any questions regarding the scope of this
proposed action, consult the person listed in the preceding FOR FURTHER
INFORMATION CONTACT section.
B. Public Participation
The EPA requests comment on all aspects of the proposed aircraft
endangerment and cause or contribute findings and the Advance Notice of
Proposed Rulemaking (ANPR). This section describes how you can
participate in this process.
If you submitted comments on the issues raised by this proposal in
dockets for other, earlier Agency efforts (e.g., the 2009 Endangerment
and Cause or Contribute Findings for Greenhouse Gases Under Section 202
of the Clean Air Act or the Advance Notice of Proposed Rulemaking on
Regulating Greenhouse Gases under the Clean Air Act), you must still
submit your comments to the docket for this action (EPA-HQ-OAR-2014-
0828) by the deadline if you want them to be considered.
1. What should I consider as I prepare my comments for the EPA?
We are opening a formal comment period by publishing this document.
We will accept comments during the period indicated in the DATES
section. If you have an interest in the proposed aircraft endangerment
and cause or contribute findings and/or the ANPR described in this
document, we encourage you to comment on any aspect of this rulemaking.
Tips for Preparing Your Comments
When submitting comments, remember to:
Identify the rulemaking by docket number and other
identifying information (subject heading, Federal Register date and
page number).
Follow directions--The agency may ask you to respond to
specific questions or organize comments by referencing a Code of
Federal Regulations (CFR) part or section number.
Explain why you agree or disagree, suggest alternatives,
and substitute language for your requested changes.
Describe any assumptions and provide any technical
information and/or data that you used.
If you estimate potential costs or burdens, explain how
you arrived at your estimate in sufficient detail to allow for it to be
reproduced.
Provide specific examples to illustrate your concerns, and
suggest alternatives.
Explain your views as clearly as possible, avoiding the
use of profanity or personal threats.
Make sure to submit your comments by the comment period
deadline identified.
Do not submit information to the EPA containing CBI through http://www.regulations.gov or email. Clearly mark the part or all of the
information that you claim to be CBI. For CBI information on a disk or
CD-ROM that you mail to the EPA, mark the outside of the disk or CD-ROM
as CBI and then identify electronically within the disk or CD-ROM the
specific information that is claimed as CBI. In addition to one
complete version of the comment that includes information claimed as
CBI, you must submit a copy of the comment that does not contain the
information claimed as CBI for inclusion in the public docket.
Information so marked will not be disclosed except in accordance with
procedures set forth in 40 CFR part 2.
2. Public Hearing
If a hearing is held, it will provide interested parties the
opportunity to present data, views or arguments concerning the proposed
action. The EPA will make every effort to accommodate all speakers who
arrive and register. Because this hearing, if held, will be at a U.S.
government facility, individuals planning to attend the hearing should
be prepared to show valid picture identification to the security staff
in order to gain access to the meeting room. Please note that the REAL
ID Act, passed by Congress in 2005, established new requirements for
entering federal facilities. These requirements took effect July 21,
2014. If your driver's license is issued by Alaska, American Samoa,
Arizona, Kentucky, Louisiana, Maine, Massachusetts, Minnesota, Montana,
New York, Oklahoma, or the state of Washington, you must present an
additional form of identification to enter the federal buildings where
the public hearings will be held. Acceptable alternative forms of
identification include: Federal employee badges, passports, enhanced
driver's licenses and military identification cards. In addition, you
will need to obtain a property pass for any personal belongings you
bring with you. Upon leaving the building, you will be required to
return this property pass to the security desk. No large signs will be
allowed in the building, cameras may only be used outside of the
building and demonstrations will not be allowed on federal property for
security reasons. The EPA may ask clarifying questions during the oral
presentations but will not respond to the presentations at that time.
Written statements and supporting information submitted during the
comment period will be considered with the same weight as oral comments
and supporting information presented at the public hearings.
Speakers should contact Ms. JoNell Iffland (see FOR FURTHER
INFORMATION CONTACT) if they will need specific equipment, or if there
are other special needs related to providing comments at the hearing.
Oral testimony will be limited to no more than 10 minutes for each
commenter, although we may need to adjust the time for each speaker if
there is a large turnout. The EPA requests that commenters provide the
EPA with three copies of their oral testimony in hard copy form the day
of the hearing or an electronic copy in advance of the hearing date.
Verbatim transcripts of the hearings and written
[[Page 37761]]
statements will be included in the docket for the rulemaking. The EPA
will make every effort to follow the schedule as closely as possible on
the day of the hearing; however, please plan for the hearing to run
either ahead of schedule or behind schedule.
Information regarding the hearing (including information as to
whether or not one will be held) will be available at http://www.epa.gov/otaq/aviation.htm. Again, if we do not receive a request to
speak at the August 11, 2015 public hearing by July 13, 2015 the
hearing will be cancelled.
C. Did the EPA conduct a peer review before issuing this notice?
As outlined in section IV.A of this action, the EPA's approach to
providing the technical and scientific information to inform the
Administrator's judgment regarding the question of whether greenhouse
gases endanger public health and welfare was to rely primarily upon the
recent, major assessments by the U.S. Global Change Research Program
(USGCRP), the Intergovernmental Panel on Climate Change (IPCC), and the
National Research Council (NRC) of the National Academies. These
assessments draw synthesis conclusions across thousands of individual
peer-reviewed studies that appear in scientific journals, and the
reports themselves undergo additional peer review. The EPA has
considered the processes and procedures employed by the USGCRP, IPCC,
and the NRC, and has determined that these assessments have been
adequately peer reviewed in a manner commensurate with the EPA's Peer
Review Policy \1\ and the guidelines in Office of Management and
Budget's (OMB) Final Information Quality Bulletin for Peer Review
(``OMB Bulletin'') for highly influential scientific assessments.
According to guidelines in the EPA's Peer Review Handbook, if the
Agency has determined that information has already been subject to
adequate peer review, then it is not necessary to have further peer
review of that information.\2\
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\1\ U.S. EPA, 2006: EPA Peer Review Policy. Available at http://www.epa.gov/peerreview/ (Last accessed May 12, 2015).
\2\ U.S. EPA, 2012: EPA Peer Review Handbook, Third Edition.
Available at http://www.epa.gov/peerreview/pdfs/peer_review_handbook_2012.pdf (Last accessed May 12, 2015).
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The EPA also cites data from its annual Inventory of U.S.
Greenhouse Gas Emissions and Sinks report,\3\ which the Agency has
determined to have been adequately reviewed in accordance with the OMB
Bulletin and the EPA's Peer Review Handbook. For the presentation of
emissions inventory information to support the cause or contribute
finding, the EPA disaggregated the existing data in one area of the GHG
Inventory (for the General Aviation Jet Fuel Category) and had the
disaggregation methodology and results peer reviewed in accordance with
the EPA's Peer Review Handbook. The EPA Science Advisory Board reviewed
this approach to the underlying technical and scientific information
supporting this action, and concluded that the approach had precedent
and the action will be based on well-reviewed information. All relevant
peer review documentation is located in the docket for today's action
(EPA-HQ-OAR-2014-0828).
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\3\ U.S. EPA, 2015: Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2013, 564 pp. Available at http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html#fullreport, (Last
accessed May 12, 2015).
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D. Children's Environmental Health
As described in detail in section IV of this preamble, the
scientific evidence and conclusions in the USGCRP, IPCC, and the NRC
assessment reports cited in the 2009 Endangerment Finding \4\ indicate
that children are uniquely vulnerable to climate change related health
effects given behavioral, developmental, and physiological factors. The
new assessment literature published since 2009 strengthens these
conclusions by providing more detailed findings regarding children's
vulnerabilities and projected impacts they may experience.
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\4\ U.S. EPA, 2009: Endangerment and Cause or Contribute
Findings for Greenhouse Gases Under Section 202(a) of the Clean Air
Act; Final Rule, 74 FR 66496 (December 15, 2009) (``2009
Endangerment Finding''); 74 FR 18886 (April 24, 2009) (``Proposed
2009 Endangerment Finding'').
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These assessments describe that children will be disproportionately
impacted by climate change given the unique physiological and
developmental factors that occur during this lifestage. Impacts to
children are expected from heat waves, air pollution, infectious and
waterborne illnesses, and mental health effects resulting from extreme
weather events. In addition, the assessments find that climate change
will influence production of pollen that affects asthma and other
allergic respiratory diseases, to which children are among those
especially susceptible.
E. Environmental Justice
As described in detail in section IV below, the scientific evidence
and conclusions in the USGCRP, IPCC, and the NRC assessment reports
cited in the 2009 Endangerment Finding indicate that certain
populations are most vulnerable to the health and welfare effects of
climate change, including the elderly, the poor, and indigenous peoples
in the United States, particularly Alaska Natives. The more recent
assessment reports strengthen these conclusions by providing more
detail regarding these populations' vulnerabilities and projected
impacts they may experience.
In addition, the most recent assessment reports provide new
analysis about how low-income populations and some populations defined
jointly by ethnic/racial characteristics and geographic location are
vulnerable to certain climate change health impacts, raising
environmental justice concerns. Factors that contribute to increased
vulnerability to the health effects of climate change include limited
resources to adapt to and recover from climate impacts, as well as
existing health disparities (e.g., higher prevalence of chronic health
conditions such as diabetes).
II. Introduction: Overview and Context for This Proposal
A. Summary
Pursuant to section 231(a)(2)(A) of the Clean Air Act (CAA or Act),
the Administrator proposes to find that greenhouse gas (GHG) emissions
from aircraft engines used in certain types of aircraft (referred to as
``covered aircraft'' throughout this notice) contribute to air
pollution that endangers public health and welfare. Covered aircraft
would be those aircraft to which ICAO has agreed the international
CO2 standard would apply: \5\ subsonic jet aircraft with a
maximum takeoff mass (MTOM) greater than 5,700 kilograms, and subsonic
propeller-driven (e.g., turboprop) aircraft with a MTOM greater than
8,618 kilograms. Examples of covered aircraft would include smaller jet
aircraft such as the Cessna Citation CJ2+ and the Embraer E170, up to
and including the largest commercial jet aircraft--the Airbus A380 and
the Boeing 747. Other examples of covered aircraft would include larger
turboprop aircraft, such as the ATR 72 and the Bombardier Q400.
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\5\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for the
Aeroplane CO2 Emissions Standards, Circular (Cir) 337, AN/192,
Available at: http://www.icao.int/publications/catalogue/cat_2015_en.pdf. The ICAO Circular 337 is found on page 85 of the
catalog and is copyright protected; Order No. CIR337 (last accessed
May 12, 2015.
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In this proposed action, the EPA relies primarily on the extensive
scientific and technical evidence in the record supporting the
Endangerment and Cause or Contribute Findings for Greenhouse Gases
Under Section 202(a) of the Clean Air Act; Final Rule, 74 FR 66496,
(December 15, 2009) (collectively
[[Page 37762]]
referred to as the 2009 Endangerment Finding in this action). This
includes the major, peer-reviewed scientific assessments that were used
to address the question of whether GHGs in the atmosphere endanger
public health and welfare, and on the analytical framework and
conclusions upon which the EPA relied in making that finding. The
Administrator's view is that the body of scientific evidence amassed in
the record for the 2009 Endangerment Finding also compellingly supports
an endangerment finding under CAA section 231(a). Furthermore, this
proposed finding under section 231 reflects the EPA's careful
consideration not only of the scientific and technical record for the
2009 Endangerment Finding, but also of science assessments released
since 2009, which, as illustrated below, strengthen and further support
the judgment that GHGs in the atmosphere may reasonably be anticipated
to endanger public health and welfare. No information or analyses
published since late 2009 suggest that it would be reasonable for the
EPA to now reach a different or contrary conclusion for purposes of CAA
section 231(a)(2)(A) than the Agency reached for purposes of section
202(a). However, as explained below, in proposing this finding for
purposes of section 231, we are not reopening or revising our prior
findings under CAA section 202.
The Administrator is proposing to define the ``air pollution''
referred to in section 231(a)(2)(A) of the CAA to be the mix of six
well-mixed GHGs: CO2, methane, nitrous oxide,
hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. This is
the same definition that was used for the finding for purposes of
section 202(a). It is the Administrator's judgment that the total body
of scientific evidence compellingly supports a positive endangerment
finding that elevated concentrations of the six well-mixed GHGs
constitute air pollution that endangers both the public health and the
public welfare of current and future generations within the meaning of
section 231(a) of the Clean Air Act.
Under section 231 of the CAA, the Administrator must also determine
whether emissions of any air pollutant from a class or classes of
aircraft engines cause or contribute to the air pollution that may
reasonably be anticipated to endanger public health or welfare.
Following the rationale outlined in the 2009 Endangerment Finding, the
Administrator in this action is proposing to use the same definition of
the air pollutant as was used for purposes of section 202(a) for
purposes of making the cause or contribute determination under section
231(a)--that is, the aggregate group of the same six well-mixed GHGs.
Based on the data summarized in section V, the Administrator is
proposing to find that GHG emissions from aircraft engines used in
covered aircraft, contribute to the air pollution that endangers public
health and welfare under section 231(a).
The Administrator's proposed findings come in response to a citizen
petition submitted by Friends of the Earth, Oceana, the Center for
Biological Diversity, and Earthjustice (Petitioners) requesting that
the EPA issue an endangerment finding and standards under section
231(a)(2)(A) of the Act for the GHG emissions from aircraft. The EPA is
not proposing or taking action under any other provision of the CAA.
Further, the EPA anticipates that ICAO will adopt a final
CO2 emissions standard in February 2016. This proposal, and
any final endangerment and cause or contribute findings for aircraft
engine GHG emissions, are also part of preparing for a possible
subsequent domestic rulemaking process to adopt standards that are of
at least equivalent stringency as the anticipated ICAO CO2
standards. Once an international standard is finalized by ICAO, member
states are then required to adopt standards that are of at least
equivalent stringency to those set by ICAO. Section II. D provides
additional discussion of the international aircraft standard-setting
process.
B. Background Information Helpful to Understanding This Proposal
1. Greenhouse Gases and Their Effects
GHGs in the atmosphere effectively trap some of the Earth's heat
that would otherwise escape to space. GHGs are both naturally occurring
and anthropogenic. The primary GHGs directly emitted by human
activities include CO2, methane, nitrous oxide,
hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. Of these
six gases, two (CO2 and nitrous oxide) are emitted by
aircraft engines.
These six gases, once emitted, remain in the atmosphere for decades
to centuries. Thus, they become well mixed globally in the atmosphere
and their concentrations accumulate when emissions exceed the rate at
which natural processes remove them from the atmosphere. Observations
of the Earth's globally averaged combined land and ocean surface
temperature over the period 1880 to 2012 show a warming of 0.85 [0.65
to 1.06] degrees Celsius or 1.53 [1.17 to 1.91] degrees Fahrenheit.\6\
The heating effect caused by the human-induced buildup of these and
other GHGs in the atmosphere, plus other human activities (e.g., land
use change and aerosol emissions), is extremely likely (>95 percent
likelihood) to be the cause of most of the observed global warming
since the mid-20th century.\7\ A detailed explanation of climate change
and its impact on health, society, and the environment is included in
the record for the 2009 Endangerment Finding. The relevant scientific
information from that record has also been included in the docket for
this proposed determination under CAA section 231 (EPA-HQ-OAR-02914-
0828). Section IV of this preamble discusses this information, as well
as information from the most recent scientific assessments, in the
context of the Administrator's proposed endangerment finding under CAA
section 231.
---------------------------------------------------------------------------
\6\ ``IPCC, 2013: Summary for Policymakers. In: Climate Change
2013: The Physical Science Basis. Contribution of Working Group I to
the Fifth Assessment Report of the Intergovernmental Panel on
Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor,
S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley
(eds.)]. Cambridge University Press, 29 pp.
\7\ Ibid.
---------------------------------------------------------------------------
The U.S. transportation sector constitutes a meaningful part of
total U.S. and global anthropogenic GHG emissions. In 2013, aircraft
remained the single largest GHG-emitting transportation source not yet
subject to any GHG regulations. Aircraft clearly contribute to U.S.
transportation emissions, accounting for 11 percent of all U.S
transportation GHG emissions and representing more than 3 percent of
total U.S. GHG emissions in 2013.\8\ Globally, U.S. aircraft GHG
emissions represent 29 percent of all global aircraft emissions and 0.5
percent of total global GHG emissions. Section V of this preamble
provides detailed information on aircraft GHG emissions in the context
of the Administrator's proposed cause or contribute finding under CAA
section 231.
---------------------------------------------------------------------------
\8\ U.S. EPA, 2015: Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2013, 564 pp. Available at http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html#fullreport, (last
accessed May 12, 2015).
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2. Statutory Basis for This Proposal
Section 231(a)(2)(A) of the CAA states that ``The Administrator
shall, from time to time, issue proposed emission standards applicable
to the emission of any air pollutant from any class or classes of
aircraft engines which in [her] judgment causes, or contributes to, air
pollution which may reasonably be anticipated to endanger public health
or welfare.''
[[Page 37763]]
Before the Administrator may issue standards addressing emissions
of GHGs under section 231, the Administrator must satisfy a two-step
test. First, the Administrator must decide whether, in her judgment,
the air pollution under consideration may reasonably be anticipated to
endanger public health or welfare. Second, the Administrator must
decide whether, in her judgment, emissions of an air pollutant from
certain classes of aircraft engines cause or contribute to this air
pollution.\9\ If the Administrator answers both questions in the
affirmative, she must issue standards under section 231. See
Massachusetts v. EPA, 549 U.S. 497,533 (2007) (interpreting analogous
provision in CAA section 202). Section III of this preamble summarizes
the legal framework for this proposed action under CAA section 231.
Typically, past endangerment and cause or contribute findings have been
proposed concurrently with proposed standards under various sections of
the CAA, including section 231. Comment has been taken on these
proposed findings as part of the notice and comment process for the
emission standards. See, e.g., Rulemaking for non-road compression-
ignition engines under section 213(a)(4) of the CAA, Proposed Rule at
58 FR 28809, 28813-14 (May 17, 1993), Final Rule at 59 FR 31306, 31318
(June 17, 1994); Rulemaking for highway heavy-duty diesel engines and
diesel sulfur fuel under sections 202(a) and 211(c) of the CAA,
Proposed Rule at 65 FR 35430 (June 2, 2000), and Final Rule 66 FR 5002
(January 18, 2001). However, there is no requirement that the
Administrator propose the endangerment and cause or contribute findings
concurrently with proposed standards. See 74 FR 66502 (December 26,
2001), (explaining that nothing in section 202(a) requires the EPA to
propose or issue endangerment and cause or contribute findings in the
same rulemaking, and that Congress left the EPA discretion to choose an
approach that satisfied the requirements of section 202(a)). The same
analysis applies to section 231(a)(2)(A), which is analogous to section
202(a). The EPA is choosing to propose these findings at this time for
a number of reasons, including its previous commitment to issue such
proposed findings in response to a 2007 citizens' petition.\10\
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\9\ To clarify the distinction between air pollution and air
pollutant, the air pollution is the atmospheric concentrations and
can be thought of as the total, cumulative stock of GHGs in the
atmosphere. The air pollutants, on the other hand, are the emissions
of GHGs and can be thought of as the flow that changes the size of
the total stock.
\10\ Center for Biological Diversity, Center for Food Safety,
Friends of the Earth, International Center for Technology
Assessment, and Oceana, 2007: Petition for Rulemaking Under the
Clean Air Act to Reduce the Emissions of Air Pollutants from
Aircraft the Contribute to Global Climate Change, December 5.
Available at http://www.epa.gov/otaq/aviation.htm (last accessed May
12, 2015).
---------------------------------------------------------------------------
The Administrator is applying the rulemaking provisions of CAA
section 307(d) to this action, pursuant to CAA section 307(d)(1)(V),
which provides that the provisions of 307(d) apply to ``such other
actions as the Administrator may determine.'' \11\ Any standard setting
rulemaking under section 231 will also be subject to the notice and
comment rulemaking procedures under 307(d), as provided in CAA section
307(d)(1)(F) (applying the provisions of 307(d) to the promulgation or
revision of any aircraft emission standard under section 231). Thus,
these proposed findings will be subject to the same rulemaking
requirements that would apply if the proposed findings were part of a
standard-setting rulemaking.
---------------------------------------------------------------------------
\11\ As the Administrator is applying the provisions of section
307(d) to this rulemaking under section 307(d)(1)(V), we need not
determine whether those provisions would apply to this action under
section 307(d)(1)(F).
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C. The EPA's Responsibilities Under the Clean Air Act
The CAA provides broad authority to combat air pollution to protect
public health and welfare. Cars, trucks, construction equipment,
airplanes, and ships, as well as a broad range of electric generation,
industrial, commercial and other facilities, are subject to various CAA
programs. Implementation of the Act over the past four decades has
resulted in significant reductions in air pollution while the nation's
economy has continued to grow.
1. The EPA's Regulation of Greenhouse Gases
In Massachusetts v. EPA, 549 U.S. 497 (2007), the Supreme Court
found that GHGs are air pollutants that can be regulated under the CAA.
The Court held that the Administrator must determine whether emissions
of GHGs from new motor vehicles cause or contribute to air pollution
which may reasonably be anticipated to endanger public health and/or
welfare, or whether the science is too uncertain to make a reasoned
decision. In making these decisions, the Administrator was bound by the
provisions of section 202(a) of the CAA. The Supreme Court decision
resulted from a petition for rulemaking under section 202(a) filed by
more than a dozen environmental, renewable energy, and other
organizations.
Following the Supreme Court decision, the EPA proposed (74 FR
18886, April 24, 2009) and then finalized (74 FR 66496, December 15,
2009) the 2009 Endangerment Finding, which can be summarized as
follows:
Endangerment Finding: The Administrator found that the
then-current and projected concentrations of the six key well-mixed
GHGs--CO2, methane, nitrous oxide, hydrofluorocarbons,
perfluorocarbons, and sulfur hexafluoride--in the atmosphere threaten
the public health and welfare of current and future generations.
Cause or Contribute Finding: The Administrator found that
the combined emissions of these well-mixed GHGs from new motor vehicles
and new motor vehicle engines contribute to the GHG pollution which
threatens public health and welfare.
The findings did not themselves impose any requirements on industry
or other entities. However, these findings compelled the EPA to
promulgate GHG emission standards for new motor vehicles under section
202(a). Subsequently, in May 2010 the EPA, in collaboration with the
National Highway Traffic Safety Administration (NHTSA), finalized Phase
1 GHG emission standards for light-duty vehicles (2012-2016 model
years).\12\ This was followed in August 2011 by adoption of the first-
ever GHG emission standards for heavy-duty engines and vehicles (2014-
2018 model years).\13\ On August 29, 2012, the second phase of the GHG
emission standards for light-duty vehicles (2017-2025 model years) was
finalized further reducing GHG emissions from light-duty vehicles.\14\
In 2014, the President directed the EPA and the Department of
Transportation to set standards by March 2016 that further increase
fuel efficiency and reduce GHG emissions from medium- and heavy-duty
vehicles.\15\
---------------------------------------------------------------------------
\12\ U.S. EPA, 2010: Light-Duty Vehicle Greenhouse Gas Emission
Standards and Corporate Average Fuel Economy Standards; Final Rule,
75 FR 25324 (May 7, 2010).
\13\ US EPA, 2011: Greenhouse Gas Emissions Standards and Fuel
Efficiency Standards for Medium- and Heavy-Duty Engines and
Vehicles; Final Rule, 76 Federal Register 57106 (September 15,
2011).
\14\ U.S. EPA, 2012: 2017 and Later Model Year Light-Duty
Vehicle Greenhouse Gas Emissions and Corporate Average Fuel Economy
Standards; Final Rule, 77 FR 62623 (October 15, 2012).
\15\ Executive Office of the President, 2014: Remarks by the
President on Fuel Efficiency Standards of Medium and Heavy-Duty
Vehicles, Office of the Press Secretary, February 18. Available at:
http://www.whitehouse.gov/the-press-office/2014/02/18/remarks-president-fuel-efficiency-standards-medium-and-heavy-duty-vehicl
(last accessed May 12, 2015).
---------------------------------------------------------------------------
[[Page 37764]]
The GHG rules for cars and trucks have been supported by a broad
range of stakeholders, including states, major automobile and truck
manufacturers, and environmental and labor organizations. Together
these new standards for cars and trucks are resulting in significant
reductions in GHG emissions, and over the lifetime of these vehicles
GHG emissions will have been reduced by 6 billion metric
tons.16 17
---------------------------------------------------------------------------
\16\ U.S. EPA. ``EPA and NHTSA Set Standards to Reduce
Greenhouse Gases and Improve Fuel Economy for Model Years 2017-2025
Cars and Light Trucks.'' Office of Transportation and Air Quality
Document No. EPA-420-F-12-051, August 2012. Available at http://www.epa.gov/otaq/climate/documents/420f12051.pdf (last accessed May
26, 2015). See also US EPA, 2012: Regulatory Impact Analysis: Final
Rulemaking for 2017-2025 Light-Duty Vehicle Greenhouse Gas Emissions
Standards and Corporation Average Fuel Economy Standards, August,
Document No. EPA-420-R-12-016, Table 7.4-2. Available at: http://www.epa.gov/oms/climate/documents/420r12016.pdf (last accessed May
12, 2015).
\17\ 76 FR 57106 (September 15, 2011).
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On June 25, 2013, President Obama announced a Climate Action Plan
that set forth a series of executive actions to further reduce GHGs,
prepare the U.S. for the impacts of climate change, and lead
international efforts to address global climate change.\18\ As part of
the Climate Action Plan, the President issued a Presidential Memorandum
directing the EPA to work expeditiously to complete carbon pollution
standards for the power sector.\19\ In response, in January 2014, the
EPA proposed carbon pollution standards for new electric utility
generating units.\20\ This was followed in June 2014, by proposed
standards to address carbon pollution from modified and reconstructed
power plants \21\ and from existing power plants.\22\
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\18\ Executive Office of the President, 2013: The President's
Climate Action Plan, June 25. Available at: http://www.whitehouse.gov/sites/default/files/image/president27sclimateactionplan.pdf (last accessed May 26, 2015).
\19\ Executive Office of the President, 2013: Presidential
Memorandum--Power Sector Carbon Pollution Standards, Office of the
Press Secretary, June 25. Available at: http://www.whitehouse.gov/the-press-office/2013/06/25/presidential-memorandum-power-sector-carbon-pollution-standards (last accessed May 12, 2015).
\20\ U.S. EPA, 2014: Standards of Performance for Greenhouse Gas
Emissions From New Stationary Sources: Electric Utility Generating
Units; Proposed Rule, 79 FR 1430 (January 8, 2014).
\21\ U.S. EPA, 2014: Carbon Pollution Standards for Modified and
Reconstructed Stationary Sources: Electric Utility Generating Units;
Proposed Rules, 79 FR 34960 (June 18, 2014).
\22\ U.S. EPA, 2014: Carbon Pollution Emission Guidelines for
Existing Stationary Sources: Electric Utility Generating Units;
Proposed Rule, 79 FR 34830 (June 18, 2014).
---------------------------------------------------------------------------
In the Climate Action Plan, the President also indicated that the
U.S. was working internationally to make progress in a variety of areas
and specifically noted the progress being made by ICAO to develop
global CO2 emission standards for aircraft.\23\ The proposed
endangerment and cause or contribute findings for aircraft GHG
emissions under section 231(a)(2)(A) of the CAA are a preliminary but
necessary first step to begin to address GHG emissions from the
aviation sector, the highest-emitting category of transportation
sources that the EPA has not yet addressed. As presented in more detail
in Section V of this preamble, total U.S. aircraft GHG emissions in
2013 represented 11 percent of GHG emissions from the U.S.
transportation sector,\24\ and in 2010, the latest year with complete
global emissions data, U.S. aircraft GHG emissions represented 29
percent of global aircraft GHG emissions.25 26 U.S. aircraft
GHG emissions are projected to increase by almost 50 percent over the
next two decades.\27\ See section V of this preamble for more
information about the data sources that compose the aircraft GHG
emissions inventory.
---------------------------------------------------------------------------
\23\ Executive Office of the President, 2013: The President's
Climate Action Plan at 21, June. Available at: http://www.whitehouse.gov/sites/default/files/image/president27sclimateactionplan.pdf (last accessed May 12, 2015).
\24\ U.S. EPA, 2015: Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2013, 564 pp. Available at http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html#fullreport (last
accessed May 12, 2015).
\25\ Ibid.
\26\ IPCC, 2014: Climate Change 2014: Mitigation of Climate
Change. Contribution of Working Group III to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change [Edenhofer,
O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth,
A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J.
Savolainen, S. Schl[ouml]mer, C. von Stechow, T. Zwickel and J.C.
Minx (eds.)]. Cambridge University Press, pp. 599-670.
\27\ As discussed in section V.B.2.c., fuel burn growth rates
for air carriers and general aviation aircraft operating on jet fuel
are projected to grow by 49 percent from 2010 to 2035, and this
provides a scaling factor for growth in GHG emissions which would
increase at a similar rate as the fuel burn by 2030, 2035, and 2040.
FAA, 2015: FAA Aerospace Forecast Fiscal Years 2015-2035, 134 pp.
Available at https://www.faa.gov/about/office_org/headquarters_offices/apl/aviation_forecasts/aerospace_forecasts/2015-2035/media/2015_National_Forecast_Report.pdf (last accessed May
12, 2015).
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2. Background on the Aircraft Petition, 2008 ANPR, and D.C. District
Court Decision
Section 231(a)(2)(A) of the CAA directs the Administrator of the
EPA to, from time to time, propose aircraft engine emissions standards
applicable to the emission of any air pollutant from any classes of
aircraft engines which in her judgment causes or contributes to air
pollution which may reasonably be anticipated to endanger public health
or welfare.
On December 5, 2007, Friends of the Earth, Oceana, the Center for
Biological Diversity, Earthjustice, and others (Petitioners) sent a
letter to the EPA petitioning the Agency to undertake rulemaking
regarding GHG emissions from aircraft.\28\ Specifically, Petitioners
requested that the EPA make a finding that GHG emissions from aircraft
engines ``may reasonably be anticipated to endanger public health and
welfare'' and that the EPA promulgate standards for GHG emissions from
aircraft.
---------------------------------------------------------------------------
\28\ Center for Biological Diversity, Center for Food Safety,
Friends of the Earth, International Center for Technology
Assessment, and Oceana, 2007: Petition for Rulemaking Under the
Clean air Act to Reduce the Emissions of Air Pollutants from
Aircraft the Contribute to Global Climate Change, December 5.
Available at http://www.epa.gov/otaq/aviation.htm (last accessed May
12, 2015).
---------------------------------------------------------------------------
Following the Supreme Court's decision in Massachusetts v. EPA in
2007, the EPA issued an ANPR in 2008 presenting information relevant to
potentially regulating GHGs under the Act, and soliciting public
comment on how to respond to the Court's ruling and the potential
ramifications of the Agency's decision to regulate GHGs under the CAA.
This ANPR described and solicited comment on numerous petitions the
Agency had received to regulate GHG emissions from both stationary and
mobile sources, including aircraft. 73 FR 44354, 44468-44473 (July 30,
2008). With regard to aircraft, the Agency sought comment on the impact
of aircraft operations on GHG emissions and the potential for
reductions in GHG emissions from these operations.
In response to the ANPR, the EPA received comments from a wide
range of aviation sector stakeholders including industry trade groups,
individual manufacturers, states and local governments, and
nongovernmental organizations (NGOs). Industry groups and individual
manufacturers stressed that fuel costs (and market forces) created an
economic incentive to reduce fuel consumption and thus GHG emissions.
One industry association indicated its commitment to achieve an
additional 30 percent fuel efficiency improvement by 2025. Another
commenter identified engine technologies that were improving fuel
efficiency by more than 15 percent in the next generation of aircraft.
With regard to CO2 engine emissions standards, these
commenters felt that
[[Page 37765]]
international CO2 standards for aircraft engines were not
necessary and that, if pursued, such standards would burden the
industry and necessitate the development of new test procedures if
CO2 emissions standards were based on aircraft cruise
conditions instead of landing and takeoff operations (LTO). Industry
commenters also argued that other potential approaches to reducing
aircraft related emissions, such as averaging of GHGs among existing
aircraft fleets and cap-and-trade schemes as existed in the European
Union, were beyond the scope of the EPA's authority under section 231
of the CAA. Finally, industry commenters noted that any program
developed by the EPA should incentivize market forces and provide for
flexibility.
State/local governments and NGO commenters felt strongly that the
EPA had clear authority to find endangerment under section 231 and that
there were multiple options to reduce aircraft emissions, so that the
Agency must set a GHG emissions standard for aircraft engines as states
were preempted from doing so under CAA section 233. These commenters
also argued that GHG standards for aircraft engines could provide
aircraft manufacturers the incentive to renew or redesign aircraft and
to adopt advanced engines brought to market. In addition these
commenters suggested that an engine GHG standard could be set as a
function of thrust similar to ICAO's standard for oxides of nitrogen
(NOX) \29\ and should also include provisions for an
averaging, banking, and trading (ABT) program.\30\ Some commenters also
stated their support for fleet-wide (in-use fleet) emission reductions
through a cap-and-trade system. Finally, these stakeholders stated
that, absent the EPA rulemaking, quick international actions were
unlikely and that the EPA should engage internationally to push for
action on reducing CO2 emissions from aircraft.
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\29\ Sections II.D.1 and II.E provide an overview of the history
ICAO's regulation of aircraft engine NOX emissions from
1981 through 2012 and the EPA's adoption of equivalent aircraft
engine NOX standards under the CAA.
\30\ ABT programs have been utilized in a number of Clean Air
Act programs to provide greater flexibilities that lower overall
costs by allowing a manufacturer to comply with performance
standards through averaging emissions among the vehicles it
manufactures. Companies that achieve extra pollution reductions can
bank these as `credits'' and then `trade or sell' emission credits
to other companies, typically those that face higher costs to
control pollution. Well-designed ABT programs can sometimes achieve
greater emissions reductions at less cost and provide incentives for
technology innovation.
---------------------------------------------------------------------------
On July 31, 2008, Earthjustice, on behalf of Petitioners, notified
the EPA of its intent to file suit under CAA section 304(a) against the
EPA for the Agency's alleged unreasonable delay in responding to its
aircraft petition and in making an endangerment finding under section
231. On June 11, 2010, Petitioners filed a complaint against the EPA in
the U.S. District Court for the District of Columbia claiming that,
among other things, the EPA had unreasonably delayed because it had
failed to answer the 2007 Petition and to determine whether or not GHG
emissions from aircraft cause or contribute to air pollution which may
reasonably be anticipated to endanger public health and/or welfare.
The District Court found that while CAA section 231 generally
confers broad discretion to the EPA in determining what standards to
promulgate, section 231(a)(2)(A) imposed a nondiscretionary duty on the
EPA to make a finding with respect to endangerment from aircraft GHG
emissions. Center for Biological Diversity, et al. v. EPA, 794 F. Supp.
2d 151 (D.D.C. 2011). This ruling was issued in response to EPA's
motion to dismiss the case on jurisdictional grounds and did not
address the merits of the Plaintiffs' claims regarding the Agency's
alleged unreasonable delay. Therefore, it did not include an order for
the EPA to make such a finding by a certain date. In a subsequent
ruling on the merits, the Court found that the Plaintiffs had not shown
that EPA had unreasonably delayed in making an endangerment
determination regarding GHG emissions from aircraft. Center for
Biological Diversity, et al. v. EPA, No. 1:10-985 (D.D.C. March, 20,
2012). Thus, the Court did not find the EPA to be liable based on the
Plaintiffs' claims and did not place the Agency under a remedial order
to make an endangerment finding or to issue standards. The Plaintiffs
did not appeal this ruling to the U.S. Court of Appeals for the D.C.
Circuit.
The EPA issued a Response to the Aircraft Petition \31\ on June 27,
2012 stating our intention to move forward with a proposed endangerment
finding for aircraft GHG emissions under section 231, while explaining
that it would take the Agency significant time to complete this action.
The EPA explained that the Agency would not begin this effort until
after the U.S. Court of Appeals completed its then-pending review of
the previous section 202 Endangerment Finding, since the then-awaited
ruling might provide important guidance for the EPA in conducting
future GHG endangerment findings. The EPA further explained that after
receiving the Court of Appeal's ruling, it would take at least 22
months from that point for the Agency to conduct an additional finding
regarding aircraft GHG emissions.
---------------------------------------------------------------------------
\31\ U.S. EPA, 2012: Memorandum in Response to Petition
Regarding Greenhouse Gas Emissions from Aircraft, June 14. Available
at http://www.epa.gov/otaq/aviation.htm (last accessed May 12, 2015)
and Docket EPA-HQ-OAR-2014-0828.
---------------------------------------------------------------------------
Meanwhile, the Court upheld EPA's section 202 findings in a
decision of a three-judge panel on June 26, 2012, and denied petitions
for rehearing of that decision on December 20, 2012. Coalition for
Responsible Regulation, Inc., v. EPA, 684 F.3d 102 (D.C. Cir. 2012),
reh'g denied 2012 U.S. App. LEXIS 26315, 25997 (D.C. Cir. 2012).\32\
Given these rulings, we are proceeding with this proposed findings
regarding aircraft engine GHG emissions as a further step toward
responding to the Petition for Rulemaking.
---------------------------------------------------------------------------
\32\ Petitions for certiorari were filed in the Supreme Court,
and the Supreme Court granted six of those petitions but ``agreed to
decide only one question: ``Whether EPA permissibly determined that
its regulation of greenhouse gas emissions from new motor vehicles
triggered permitting requirements under the Clean Air Act for
stationary sources that emit greenhouse gases''. Utility Air Reg.
Group v. EPA, 134 S. Ct. 2427, 2438 (2014); see also Virginia v.
EPA, 134 S. Ct. 418 (2013), Pac. Legal Found. v. EPA, 134 S. Ct. 418
(2013), and CRR, 134 S. Ct. 468 (2013) (all denying cert.). Thus,
the Supreme Court did not disturb the D.C. Circuit's holding that
affirmed the 2009 Endangerment Finding.
---------------------------------------------------------------------------
D. U.S. Aircraft Regulations and the International Community
The EPA and the Federal Aviation Administration (FAA) traditionally
work within the standard-setting process of ICAO's Committee on
Aviation Environmental Protection (CAEP) to establish international
emission standards and related requirements. Historically, under this
approach, international emission standards have first been adopted by
ICAO, and subsequently the EPA has initiated rulemakings under CAA
section 231 to establish domestic standards equivalent to ICAO's
standards where appropriate. This approach has been affirmed as
reasonable by the U.S. Court of Appeals for the D.C. Circuit. NACAA v.
EPA, 489 F.3d 1221, 1230-32 (D.C. Cir. 2007). After EPA promulgates
aircraft engine emissions standards, CAA section 232 requires the FAA
to issue subsequent regulations to ensure compliance with these
standards when issuing certificates under its United States Code Title
49 authority. In exercising the EPA's standard-setting and FAA's
enforcement authorities, we expect to proceed using a similar approach
for the future CAA section 231 aircraft engine
[[Page 37766]]
GHG standard (which may take the form of a CO2 standard),
provided the EPA issues final positive endangerment and cause or
contribute findings under CAA section 231. This approach is contingent
on ICAO's adoption of an international aircraft CO2 standard
that is consistent with CAA section 231 and is appropriate for domestic
needs in the United States.
1. International Regulations and U.S. Obligations
As noted above, we have worked with the FAA since 1973, and later
with ICAO, to develop domestic and international standards and other
recommended practices pertaining to aircraft engine emissions. ICAO is
a United Nations (UN) specialized agency, established in 1944 by the
Convention on International Civil Aviation (Chicago Convention), ``in
order that international civil aviation may be developed in a safe and
orderly manner and that international air transport services may be
established on the basis of equality of opportunity and operated
soundly and economically.'' \33\ ICAO sets standards and regulations
necessary for aviation safety, security, efficiency, capacity and
environmental protection, and serves as the forum for cooperation in
all fields of international civil aviation. ICAO works with the Chicago
Convention's member States and global aviation organizations to develop
international Standards and Recommended Practices (SARPs), which member
States reference when developing their legally-enforceable national
civil aviation regulations. The U.S. is currently one of 191
participating ICAO member States.34 35
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\33\ ICAO, 2006: Convention on International Civil Aviation,
Ninth Edition, Document 7300/9. Available at: http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed May 12, 2015).
The ICAO Document 7300 is found on page 1 of the ICAO Products &
Services 2015 catalog and is copyright protected; Order No. 7300.
\34\ Members of ICAO's Assembly are generally termed member
States or contracting States. These terms are used interchangeably
throughout this preamble.
\35\ There are currently 191 Contracting States according to
ICAO's Web site: www.icao.int (last accessed May 12, 2015).
---------------------------------------------------------------------------
In the interest of global harmonization and international air
commerce, the Chicago Convention urges its member States to collaborate
in securing the highest practicable degree of uniformity in
regulations, standards, procedures and organization. The Chicago
Convention also recognizes that member States may adopt standards that
are more stringent than those agreed upon by ICAO. Any member State
which finds it impracticable to comply in all respects with any
international standard or procedure, or which deems it necessary to
adopt regulations or practices differing in any particular respect from
those established by an international standard, is required to give
immediate notification to ICAO of the differences between its own
practice and that established by the international standard.\36\
---------------------------------------------------------------------------
\36\ ICAO, 2006: Doc 7300-Convention on International Civil
Aviation, Ninth edition, Document 7300/9. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Document 7300 is found on page 1 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. 7300.
---------------------------------------------------------------------------
ICAO's work on the environment focuses primarily on those problems
that benefit most from a common and coordinated approach on a worldwide
basis, namely aircraft noise and engine emissions. Standards and
Recommended Practices (SARPs) for the certification of aircraft noise
and aircraft engine emissions are covered by Annex 16 of the Chicago
Convention. To continue to address aviation environmental issues, in
2004, ICAO established three environmental goals: (1) Limit or reduce
the number of people affected by significant aircraft noise; (2) limit
or reduce the impact of aviation emissions on local air quality; and
(3) limit or reduce the impact of aviation greenhouse gas emissions on
the global climate.
The Convention has a number of other features that govern
international commerce. First, member States that wish to use aircraft
in international transportation must adopt emissions standards and
other recommended practices that are at least as stringent as ICAO's
standards. Member States may ban the use of any aircraft within their
airspace that does not meet ICAO standards.\37\ Second, member States
are required to recognize the airworthiness certificates of any State
whose standards are at least as stringent as ICAO's standards, thereby
assuring that aircraft of any member State will be permitted to operate
in any other member State.\38\ Third, to ensure that international
commerce is not unreasonably constrained, a member State which elects
to adopt more stringent domestic emission standards is obligated to
notify ICAO of the differences between its standards and ICAO
standards.\39\
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\37\ ICAO, 2006: Convention on International Civil Aviation,
Article 87, Ninth Edition, Document 7300/9. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
\38\ ICAO, 2006: Convention on International Civil Aviation,
Article 33, Ninth Edition, Document 7300/9. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
\39\ ICAO, 2006: Convention on International Civil Aviation,
Article 38, Ninth Edition, Document 7300/9. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Document 7300 is found on page 1 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. 7300.
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ICAO's CAEP, which consists of Members and Observers from States,
intergovernmental and non-governmental organizations representing
aviation industry and environmental interests, undertakes ICAO's
technical work in the environmental field. The Committee is responsible
for evaluating, researching, and recommending measures to the ICAO
Council that address the environmental impacts of international civil
aviation. CAEP's terms of reference indicate that ``CAEP's assessments
and proposals are pursued taking into account: technical feasibility;
environmental benefit; economic reasonableness; interdependencies of
measures (for example, among others, measures taken to minimize noise
and emissions); developments in other fields; and international and
national programs.'' \40\ CAEP is composed of various task groups, work
groups, and other committees whose contributing members include
atmospheric, economic, aviation, environmental, and other professionals
interested in and knowledgeable about aviation and environmental
protection. The ICAO Council reviews and adopts the recommendations
made by CAEP. It then reports to the ICAO Assembly, the highest body of
the Organization, where the main policies on aviation environmental
protection are adopted and translated into Assembly Resolutions.
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\40\ CAEP's terms of reference are available at http://www.icao.int/environmental-protection/Pages/Caep.aspx#ToR (last
accessed May 12, 2015).
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At CAEP meetings, the U.S. is represented by the FAA and plays an
active role.\41\ The EPA has historically been a principal participant
in various ICAO/CAEP working groups and other international venues,
assisting and advising FAA on aviation emissions, technology, and
policy matters. In turn, the FAA assists and advises the EPA on
[[Page 37767]]
aviation technology and certification matters. If ICAO adopts a CAEP
proposal for a new environmental standard, it then becomes part of ICAO
standards and recommended practices (Annex 16 to the Chicago
Convention). 42 43
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\41\ Pursuant to the President's memorandum of August 11, 1960
(and related Executive Order No. 10883 from 1960), the Interagency
Group on International Aviation (IGIA) was established to facilitate
coordinated recommendations to the Secretary of State on issues
pertaining to international aviation. The DOT/FAA is the chair of
IGIA, and as such, the FAA represents the U.S. on environmental
matters at CAEP.
\42\ ICAO, 2008: Aircraft Engine Emissions, International
Standards and Recommended Practices, Environmental Protection, Annex
16, Volume II, Third Edition, July. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
\43\ CAEP develops new emission standards based on an assessment
of the technical feasibility, cost, and environmental benefit of
potential requirements.
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The first international standards and recommended practices for
aircraft engine emissions were recommended by CAEP's predecessor, the
Committee on Aircraft Engine Emissions (CAEE), and adopted by ICAO in
1981.\44\ These standards limited aircraft engine emissions of
hydrocarbons, carbon monoxide, and NOX. The 1981 standards
applied to newly manufactured engines, which are those engines built
after the effective date of the regulations--also referred to as in-
production engines. In 1993, ICAO adopted a CAEP/2 proposal to tighten
the original NOX standard by 20 percent and amend the test
procedures.\45\ These 1993 standards applied both to newly-certified
turbofan engines, which are those engine models that received their
initial type certificate after the effective date of the regulations--
also referred to as newly-certified engines or new engine designs--and
to in-production engines, but with different effective dates for newly-
certified engines and in-production engines. In 1995, CAEP/3
recommended a further tightening of the NOX standards by 16
percent and additional test procedure amendments, but in 1997 the ICAO
Council rejected this stringency proposal and approved only the test
procedure amendments. At the CAEP/4 meeting in 1998, the Committee
adopted a similar 16 percent NOX reduction proposal, which
ICAO approved in 1998. The CAEP/4 standards applied only to new engine
designs certified (or newly-certified engines) after December 31, 2003
(i.e., unlike the CAEP/2 standards, the CAEP/4 requirements did not
apply to in-production engines). In 2004, CAEP/6 recommended a 12
percent NOX reduction, which ICAO approved in
2005.46 47 The CAEP/6 standards applied to new engine
designs certified after December 31, 2007. In 2010, CAEP/8 recommended
a further tightening of the NOX standards by 15 percent for
new engine designs certified after December 31, 2013.48 49
The Committee also recommended that the CAEP/6 standards be applied to
in-production engines (eliminating the production of CAEP/4 compliant
engines with the exception of spare engines). ICAO approved these
recommendations in 2011, then equivalent standards (to CAEP/6 and CAEP/
8 standards) were promulgated domestically in 2012 by the EPA in
consultation with FAA.\50\
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\44\ ICAO, 2008: Aircraft Engine Emissions: Foreword,
International Standards and Recommended Practices, Environmental
Protection, Annex 16, Volume II, Third Edition, July. Available at
http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last
accessed May 12, 2015). The ICAO Annex 16 Volume II is found on page
19 of the ICAO Products & Services 2015 catalog and is copyright
protected; Order No. AN16-2.
\45\ CAEP conducts its work over a period of years. Each work
cycle is numbered sequentially and that identifier is used to
differentiate the results from one CAEP to another by convention.
The first technical meeting on aircraft emission standards was
CAEP's successor, i.e., CAEE. The first meeting of CAEP, therefore,
is referred to as CAEP/2.
\46\ CAEP/5 did not address new aircraft engine emission
standards.
\47\ ICAO, 2008: Aircraft Engine Emissions, Annex 16, Volume II,
Third Edition, July 2008, Amendment 5 effective on July 11, 2005.
Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed May 12, 2015). The ICAO Annex 16
Volume II is found on page 19 of the ICAO Products & Services 2015
catalog and is copyright protected; Order No. AN16-2.
\48\ CAEP/7 did not address new aircraft engine emission
standards.
\49\ ICAO, 2010: Committee on Aviation Environmental Protection
(CAEP), Report of the Eighth Meeting, Montreal, February 1-12, 2010,
CAEP/8-WP/80 Available in Docket EPA-HQ-OAR-2010-0687.
\50\ ICAO, 2011: Aircraft Engine Emissions, Annex 16, Volume II,
Third Edition, July 2008, Amendment 7 effective on July 18, 2011.
Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed May 12, 2015). The ICAO Annex 16
Volume II is found on page 19 of the ICAO Products & Services 2015
catalog and is copyright protected; Order No. AN16-2/E/10 (last
accessed February 5, 2015). U.S. EPA, 2012: Control of Air Pollution
from Aircraft and Aircraft Engines; Emission Standards and Test
Procedures; Final Rule, 77 FR 36342 (June 18, 2012).
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2. The International Community's Reasons for Addressing Aircraft GHG
Emissions
In October 2010, the 37th Assembly (Resolution A37-19) of ICAO
requested the development of an ICAO CO2 emissions
standard.\51\ Also, Resolution A37-19 provided a framework towards the
achievement of an environmentally sustainable future for international
aviation. With this Resolution, the ICAO Assembly agreed to a global
aspirational goal for international aviation of improving annual fuel
efficiency by two percent and stabilizing CO2 emissions at
2020 levels.\52\ The Resolution included the following statements
regarding ICAO policies and practices related to climate change.
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\51\ A consolidated statement of continuing policies and
practices related to environmental protection (known as Assembly
Resolutions) is revised and updated by the Council every three years
for adoption by the ICAO Assembly. ICAO, 2010: Resolutions Adopted
by the Assembly, 37th Session, Montreal, September 29-October 8,
2010, Provisional Edition, November.
\52\ The global aspirational goal for international aviation of
improving annual fuel efficiency by 2 percent is for the annual
international civil aviation in-service fleet. Fuel efficiency is
measured on the basis of the volume of fuel used per revenue tonne
kilometer performed. (ICAO, CAEP, Aspirational Goals and
Implementation Options, HLM-ENV/09-WP/5, High-Level Meeting on
International Aviation and Climate Change, Presented by the
Secretariat, Montreal, October 7 to 9, 2009. Available at http://www.icao.int/Meetings/AMC/MA/High%20Level%202009/hlmenv_wp005_en.pdf
(last accessed May 12, 2015).
--. . . ICAO and its member States recognize the importance of
providing continuous leadership to international civil aviation in
limiting or reducing its emissions that contribute to global climate
change;
--Reemphasizing the vital role which international aviation plays in
global economic and social development and the need to ensure that
international aviation continues to develop in a sustainable manner;
--. . . the ultimate objective of the United Nations Framework
Convention on Climate Change (UNFCCC) is to achieve stabilization of
greenhouse gas (GHG) concentrations in the atmosphere at a level
that would prevent dangerous anthropogenic interference with the
climate system; and
--Acknowledging that international aviation emissions, currently
accounting for less than 2 per cent of total global CO2
emissions, are projected to grow as a result of the continued
development of the sector.
As the above statements indicate, reducing climate impacts of
international aviation is a critical element of ICAO's strategic
objective of achieving environmental protection and sustainable
development of air transport. ICAO is currently pursuing a
comprehensive set of measures to reduce aviation's climate impact,
including alternative fuels, CO2 emissions technology-based
standards, operational improvements, and market based measures. The
development and adoption of a CO2 emissions standard is an
important part of ICAO's comprehensive set of measures.
3. Relationship of the EPA's Proposed Endangerment and Cause or
Contribute Findings to International Aircraft Standards
As described earlier, the EPA and the FAA work within the ICAO/CAEP
standard setting process to establish international emission standards
and related requirements. Under this approach international emission
standards have first been adopted by
[[Page 37768]]
ICAO (with U.S. participation and agreement), and subsequently the EPA
has initiated rulemakings under CAA section 231 to establish domestic
aircraft engine emission standards that are of at least equivalent
stringency as ICAO's standards. This approach has been affirmed as
reasonable by the U.S. Court of Appeals for the D.C. Circuit. NACAA v.
EPA, 489 F.3d 1221, 1230-32 (D.C. Cir. 2007). In exercising the EPA's
standard-setting authority, provided the EPA makes positive
endangerment and cause or contribute findings under CAA section 231 and
ICAO adopts an international aircraft CO2 standard that is
consistent with CAA section 231 and is appropriate for domestic needs
in the United States, the EPA expects to proceed along a similar
approach for the future CAA section 231 aircraft GHG standard (or
aircraft CO2 standard).
We anticipate that ICAO/CAEP will adopt a final aircraft
CO2 emissions standard in February 2016. This proposal, and
any final endangerment and cause or contribute finding for aircraft GHG
emissions, are part of preparing for the possible subsequent domestic
rulemaking process to adopt standards that are of at least equivalent
stringency as the anticipated ICAO CO2 standards. These
findings, which are factual and science-based, encompass a
determination of whether GHG emissions from aircraft cause or
contribute to air pollution which may reasonably be anticipated to
endanger public health or welfare. If positive findings are made, the
EPA will be obligated under section 231 of the CAA to set emission
standards applicable to GHG emissions from the classes of aircraft
engines for which the EPA makes the cause or contribute finding. If
positive findings are not made, the EPA will not have triggered its
obligation to set GHG emission standards under CAA section 231.
The EPA has worked diligently over the past four years within the
ICAO/CAEP process on a range of technical issues regarding aircraft
CO2 emission standards. The ANPR that accompanies this
proposal, in Section VI, discusses the issues arising in the ongoing
international proceedings and U.S. input to CAEP regarding the
international CO2 standard to help ensure transparency about
this process. In addition, in the ANPR the EPA requests public comments
on a variety of issues to assist the Agency in developing its position
with regard to these issues and the aircraft engine GHG emission
standards that it may potentially adopt under the CAA.
E. The EPA's Regulation of Aircraft Emissions
As required by the CAA, the EPA has been engaged in reducing
harmful air pollution from aircraft engines for over 40 years. In 1973,
the EPA began to regulate gaseous exhaust emissions, smoke, and fuel
venting from aircraft engines.\53\ We have occasionally revised these
regulations. In a 1997 rulemaking, for example, we made our emission
standards and test procedures more consistent with those of ICAO's CAEP
for turbofan engines used in commercial aviation with rated thrusts
greater than 26.7 kilonewtons. These ICAO requirements are generally
referred to as CAEP/2 standards.\54\ That action included new
NOX emission standards for newly manufactured commercial
turbofan engines (as described earlier, those engines built after the
effective date of the regulations that were already certified to pre-
existing standards--also referred to as in-production engines) \55\ and
for newly-certified commercial turbofan engines (as described earlier,
those engine models that received their initial type certificate after
the effective date of the regulations--also referred to as new engine
designs).\56\ It also included a carbon monoxide emission standard for
in-production commercial turbofan engines.\57\ In 2005, we promulgated
more stringent NOX emission standards for newly-certified
commercial turbofan engines.\58\ That final rule brought the U.S.
standards closer to alignment with ICAO CAEP/4 requirements that became
effective in 2004. In 2012, we issued more stringent two-tiered
NOX emission standards for newly-certified and in-production
commercial and non-commercial turbofan aircraft engines, and these
NOX standards align with ICAO's CAEP/6 and CAEP/8
requirements that became effective in 2013 and 2014,
respectively.59 60
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\53\ U.S. EPA, 1973: Emission Standards and Test Procedures for
Aircraft; Final Rule, 38 FR 19088 (July 17, 1973).
\54\ The full CAEP membership meets every three years and each
session is denoted by a numerical identifier. For example, the
second meeting of CAEP is referred to as CAEP/2, and CAEP/2 occurred
in 1994.
\55\ This does not mean that in 1997 we promulgated requirements
for the re-certification or retrofit of existing in-use engines.
\56\ In the existing EPA regulations, 40 CFR part 87, newly-
certified aircraft engines are described as engines of a type or
model of which the date of manufacture of the first individual
production model was after the implementation date. Newly
manufactured aircraft engines are characterized as engines of a type
or model for which the date of manufacturer of the individual engine
was after the implementation date.
\57\ U.S. EPA, 1997: Control of Air Pollution from Aircraft and
Aircraft Engines; Emission Standards and Test Procedures; Final
Rule, 62 FR 25355 (May 8, 1997).
\58\ U.S. EPA, 2005: Control of Air Pollution from Aircraft and
Aircraft Engines; Emission Standards and Test Procedures; Final
Rule, 70 FR 2521 (November 17, 2005).
\59\ U.S. EPA, 2012: Control of Air Pollution from Aircraft and
Aircraft Engines; Emission Standards and Test Procedures; Final
Rule, 77 FR 36342 (June 18, 2012).
\60\ While ICAO's standards were not limited to ``commercial''
aircraft engines, our 1997 standards were explicitly limited to
commercial engines, as our finding that NOX and carbon
monoxide emissions from aircraft engines cause or contribute to air
pollution which may reasonably be anticipated to endanger public
health or welfare was so limited. See 62 FR 25358 (May 8, 1997). In
the 2012 rulemaking, we expanded the scope of that finding and of
our standards pursuant to Section 231(a)(2)(A) of the Clean Air Act
to include such emissions from both commercial and non-commercial
aircraft engines based on the physical and operational similarities
between commercial and noncommercial civilian aircraft and to bring
our standards into full alignment with ICAO's.
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The EPA's actions to regulate certain pollutants emitted from
aircraft engines come directly from its authority in section 231 of the
CAA, and we have aligned the U.S. emissions requirements with those
promulgated by ICAO. In addressing CO2 emissions, however,
ICAO has moved to regulating a whole aircraft. This ICAO extension
beyond pollutant emissions from engines to the whole aircraft was
described in a 2013 ICAO circular.\61\ Several factors are considered
when addressing whole-aircraft CO2 emissions, as the
CO2 emissions are influenced by aerodynamics, weight, and
engine-specific fuel consumption. Since each of these factors may
affect aircraft engine fuel consumption, they ultimately affect
CO2 emissions. Rather than viewing CO2 as a
measurable emission from engines, therefore, ICAO now addresses
CO2 emissions as a characteristic applicable to the entirety
of the aircraft based on fuel consumption. In this proposed action, we
are giving advance notice that the EPA may propose to adopt domestic
GHG emission standards (which may take the form of CO2
standards) for aircraft engines used in covered aircraft as an
outgrowth of the international negotiations that commenced in 2010
under the auspices ICAO/CAEP. Such standards could then discharge the
EPA's duties under CAA sections 231(a)(2)(A) and 231(a)(3), if
triggered by final positive endangerment and cause or contribute
findings, to ``issue proposed emission standards applicable to the
emission of'' GHG
[[Page 37769]]
from aircraft engines and to issue final ``regulations with such
modifications as [she] deems appropriate.''
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\61\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for the
Aeroplane CO2 Emissions Standard, Circular (Cir) 337, AN/192.
Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed May 12, 2015). The ICAO Circular 337
is found on page 85 of the ICAO Products & Services 2015 catalog and
is copyright protected; Order No. CIR337.
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III. Legal Framework for This Action
The EPA has previously made an endangerment finding for GHGs under
Title II of the CAA, in the 2009 Endangerment Finding for section
202(a) source categories. In the 2009 Endangerment Finding, the EPA
explained its legal framework for making an endangerment finding under
section 202(a) of the CAA (74 FR 18886, 18890-94 (April 24, 2009), and
74 FR 66496, 66505-10 (December 15, 2009)). The text in section 202(a)
that was the basis for the 2009 Endangerment Finding addresses ``the
emission of any air pollutant from any class or classes of new motor
vehicles or new motor vehicle engines, which in [the Administrator's]
judgment cause, or contribute to, air pollution which may reasonably be
anticipated to endanger public health or welfare.'' Similarly, section
231(a)(2)(A) concerns ``the emission of any air pollutant from any
class or classes of aircraft engines which in [the Administrator's]
judgment causes, or contributes to, air pollution which may reasonably
be anticipated to endanger public health or welfare.'' Thus, the text
of the CAA section concerning aircraft emissions in section
231(a)(2)(A) mirrors the text of CAA section 202(a) that was the basis
for the 2009 Endangerment Finding.
The EPA's approach in the 2009 Endangerment Finding (described
below in Sections III.A and III.B) was affirmed by the U.S. Court of
Appeals for the D.C. Circuit in Coalition for Responsible Regulation,
Inc. v. EPA, 684 F.3d 102 (D.C. Cir. 2012), reh'g denied 2012 U.S. App.
LEXIS 26313, 26315, 25997 (D.C. Cir 2012) (CRR). In particular, the
D.C. Circuit ruled that the 2009 Endangerment Finding (including the
agency's denial of petitions for reconsideration of that Finding) was
not arbitrary or capricious, was consistent with the U.S. Supreme
Court's decision in Massachusetts v. EPA and the text and structure of
the CAA, and was adequately supported by the administrative record.
CRR, 684 F.3d at 116-128. The D.C. Circuit found that the EPA had based
its decision on ``substantial scientific evidence'' and noted that the
EPA's reliance on major scientific assessments was consistent with the
methods that decision-makers often use to make a science-based
judgment. Id. at 120-121. Petitions for certiorari were filed in the
Supreme Court, and the Supreme Court granted six of those petitions but
``agreed to decide only one question: `Whether EPA permissibly
determined that its regulation of greenhouse gas emissions from new
motor vehicles triggered permitting requirements under the Clean Air
Act for stationary sources that emit greenhouse gases.' '' Utility Air
Reg. Group v. EPA, 134 S. Ct. 2427, 2438 (2014); see also Virginia v.
EPA, 134 S. Ct. 418 (2013), Pac. Legal Found. v. EPA, 134 S. Ct. 418
(2013), and CRR, 134 S. Ct. 468 (2013) (all denying cert.). Thus, the
Supreme Court did not disturb the D.C. Circuit's holding that affirmed
the 2009 Endangerment Finding. Accordingly, the Agency proposes that it
is reasonable to use that same approach under section 231(a)(2)(A)'s
similar endangerment text, and as explained in the following
discussion, is acting consistently with that judicially sanctioned
framework for purposes of this proposed section 231 finding.
Two provisions of the CAA govern this proposal. Section
231(a)(2)(A) sets forth a two-part predicate for regulatory action
under that provision: Endangerment and cause or contribute. Section 302
of the Act contains definitions of the terms ``air pollutant'' and
``welfare'' used in section 231(a)(2)(A). These statutory provisions
are discussed below.
A. Section 231(a)(2)(A)--Endangerment and Cause or Contribute
As noted above, section 231(a)(2)(A) of the CAA (like section
202(a)) calls for the Administrator to exercise her judgment and make
two separate determinations: First, whether the relevant kind of air
pollution--here, GHGs--may reasonably be anticipated to endanger public
health or welfare, and second, whether emissions of any air pollutant
from classes of the sources in question (aircraft engines under section
231 and new motor vehicles or engines under section 202) cause or
contribute to this air pollution.\62\
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\62\ See CRR, 684 F.3d at 117 (explaining two-part analysis
under section 202(a)).
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The Administrator interprets the two-part test required under
section 231(a)(2)(A) as being the same as that explained in the 2009
Endangerment Finding. (See 74 FR 66505-06, December 15, 2009.) As in
the section 202(a) context, this analysis entails a scientific judgment
by the Administrator about the potential risks posed by GHG emissions
to public health and welfare. See CRR, 684 F.3d at 117-118.\63\
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\63\ When agencies such as the EPA make determinations based on
review of scientific data within their technical expertise, those
decisions are given an ``extreme degree of deference'' by the D.C.
Circuit, and as that court noted in reviewing the 2009 endangerment
finding, ``although we perform a searching and careful inquiry into
the facts underlying the agency's decisions, we will presume the
validity of the agency action as long as a rational basis for it is
presented.'' CRR, 684 F.3d at 120 (internal citations and marks
omitted).
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In making this scientific judgment, the Administrator is guided by
five principles. First, the Administrator is required to protect public
health and welfare. She is not asked to wait until harm has occurred
but instead must be ready to take regulatory action to prevent harm
before it occurs.\64\ The Administrator is thus to consider both
current and future risks.
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\64\ See id. at 121-122.
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Second, the Administrator is to exercise judgment by weighing
risks, assessing potential harms, and making reasonable projections of
future trends and possibilities. It follows that when exercising her
judgment the Administrator balances the likelihood and severity of
effects. This balance involves a sliding scale: On one end the severity
of the effects may be significant, but the likelihood low, while on the
other end the severity may be less significant, but the likelihood
high.\65\ At different points along this scale, the Administrator is
permitted to find endangerment. Accordingly, the Administrator need not
set a precise or minimum threshold of risk or harm as part of making an
endangerment finding, but rather may base her determination on `` `a
lesser risk of greater harm . . . or a greater risk of lesser harm' or
any combination in between.'' CRR, 684 F.3d at 123 (quoting Ethyl Corp.
v. EPA, 541 F.2d, 1, 18 (D.C. Cir. 1976)).
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\65\ See id. at 122-123 (noting that the Sec. 202(a)(1) inquiry
``necessarily entails a case-by-case, sliding scale approach''
because endangerment is `` `composed of reciprocal elements of risk
and harm, or probability and severity' '' (quoting Ethyl Corp. v.
EPA, 541 F.2d, 1, 18 (D.C. Cir. 1976)).
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Third, because scientific knowledge is constantly evolving, the
Administrator may be called upon to make decisions while recognizing
the uncertainties and limitations of the data or information available,
as risks to public health or welfare may involve the frontiers of
scientific or medical knowledge.\66\ At the same time, the
Administrator must exercise reasoned decision making, and avoid
speculative inquiries.
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\66\ See id. at 121-122.
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Fourth, the Administrator is to consider the cumulative impact of
sources of a pollutant in assessing the risks from air pollution, and
is not to look only at the risks attributable to a single source or
class of sources. We additionally note that in making an endangerment
finding, the Administrator is not limited to
[[Page 37770]]
considering only those impacts that can be traced to the amount of air
pollution directly attributable to the GHGs emitted by the subject
source classes. Such an approach would collapse the two prongs of the
test by requiring that any climate change impacts upon which an
endangerment determination is made result solely from the GHG emissions
of aircraft. See 74 FR 66542, December 15, 2009 (explaining the same
point in the context of analogous language in section 202(a)).
Similarly, the Administrator is not, in making the endangerment and
cause or contribute findings, to consider the effect of emissions
reductions from the resulting standards.\67\ The threshold endangerment
and cause or contribute criteria are separate and distinct from the
standard setting criteria that apply if the threshold findings are met,
and they serve a different purpose. Indeed, the more serious the
endangerment to public health and welfare, the more important it may be
that action be taken to address the actual or potential harm even if no
one action alone can solve the problem, and a series of actions is
called for.
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\67\ As the D.C. Circuit explained in reviewing the 2009
Endangerment Finding under analogous language in section 202(a):
``At bottom, Sec. 202(a)(1) requires EPA to answer only two
questions: Whether particular `air pollution'--here, greenhouse
gases--`may reasonably be anticipated to endanger public health or
welfare,' and whether motor-vehicle emissions `cause, or contribute
to' that endangerment.'' CRR, 648 F.3d at 117.
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Fifth, the Administrator is to consider the risks to all parts of
our population, including those who are at greater risk for reasons
such as increased susceptibility to adverse health effects. If
vulnerable subpopulations are especially at risk, the Administrator is
entitled to take that point into account in deciding the question of
endangerment. Here too, both likelihood and severity of adverse effects
are relevant. As explained previously in the 2009 Endangerment Finding
and as reiterated below for this proposed section 231 finding,
vulnerable subpopulations face serious health risks as a result of
climate change.
As the Supreme Court recognized in Massachusetts v. EPA, 549 U.S.
at 534, the EPA may make an endangerment finding despite the existence
of ``some residual uncertainty'' in the scientific record. See also
CRR, 684 F.2d at 122. Thus, this framework recognizes that regulatory
agencies such as the EPA must be able to deal with the reality that
``[m]an's ability to alter his environment has developed far more
rapidly than his ability to foresee with certainty the effects of his
alterations.'' See Ethyl Corp v. EPA, 541 F.2d 1, 6 (D.C. Cir.), cert.
denied 426 U.S. 941 (1976). Both ``the Clean Air Act `and common sense
* * * demand regulatory action to prevent harm, even if the regulator
is less than certain that harm is otherwise inevitable.' '' See
Massachusetts v. EPA, 549 U.S. at 506, n.7 (citing Ethyl Corp.); see
also CRR, 684 F.3d at 121-122.
In the 2009 Endangerment Finding, the Administrator recognized that
the scientific context for an action addressing climate change was
unique at that time because there was a very large and comprehensive
base of scientific information that had been developed over many years
through a global consensus process involving numerous scientists from
many countries and representing many disciplines. 74 FR 66506, December
15, 2009. That informational base has since grown. The Administrator
also previously recognized that there are varying degrees of
uncertainty across many of these scientific issues, which remains true.
It is in this context that she is exercising her judgment and applying
the statutory framework in this proposed section 231 finding. Further
discussion of the language in section 231(a)(2)(A), and parallel
language in 202(a), is provided below to explain more fully the basis
for this interpretation, which the D.C. Circuit upheld in the 202(a)
context.
1. The Statutory Language
The interpretation described above flows from the statutory
language itself. The phrase ``may reasonably be anticipated'' and the
term ``endanger'' in section 231(a)(2)(A) (as in section 202(a))
authorize, if not require, the Administrator to act to prevent harm and
to act in conditions of uncertainty. They do not limit her to merely
reacting to harm or to acting only when certainty has been achieved;
indeed, the references to anticipation and to endangerment imply that
to fail to look to the future or to less than certain risks would be to
abjure the Administrator's statutory responsibilities. As the D.C.
Circuit explained, the language ``may reasonably be anticipated to
endanger public health or welfare'' in CAA Sec. 202(a) requires a
``precautionary, forward-looking scientific judgment about the risks of
a particular air pollutant, consistent with the CAA's precautionary and
preventive orientation.'' CRR, 684 F.3d at 122 (internal citations
omitted). The court determined that ``[r]equiring that EPA find
`certain' endangerment of public health or welfare before regulating
greenhouse gases would effectively prevent EPA from doing the job that
Congress gave it in Sec. 202(a)--utilizing emission standards to
prevent reasonably anticipated endangerment from maturing into concrete
harm.'' Id. The same language appears in section 231(a)(2)(A), and the
same interpretation applies in that context.
Moreover, by instructing the Administrator to consider whether
emissions of an air pollutant cause or contribute to air pollution in
the second part of the two-part test, the Act makes clear that she need
not find that emissions from any one sector or class of sources are the
sole or even the major part of an air pollution problem. The use of the
term ``contribute'' clearly indicates that such emissions need not be
the sole or major cause of the pollution. Finally, the phrase ``in
[her] judgment'' authorizes the Administrator to weigh risks and to
consider projections of future possibilities, while also recognizing
uncertainties and extrapolating from existing data.
Finally, when exercising her judgment in making both the
endangerment and cause-or-contribute findings, the Administrator
balances the likelihood and severity of effects. Notably, the phrase
``in [her] judgment'' modifies both ``may reasonably be anticipated''
and ``cause or contribute.''
2. How the Origin of the Current Statutory Language Informs the EPA's
Interpretation of Section 231(a)(2)(A)
In the proposed and final 2009 Endangerment Finding, the EPA
explained that when Congress revised the section 202(a) language that
governed that finding, along with other provisions, as part of the 1977
amendments to the CAA, it was responding to decisions issued by the
D.C. Circuit in Ethyl Corp. v. EPA regarding the pre-1977 version of
section 211(c) of the Act. 74 FR 18891, (April 24, 2009); see also 74
FR 66506, (December 15, 2009). Section 231 was one of those other CAA
provisions included in the 1977 amendments; therefore, the Agency's
discussion for the 2009 Endangerment Finding regarding the history of
section 202 and how it supports the EPA's approach is also relevant for
section 231. The legislative history of those amendments, particularly
the report by the House Committee on Interstate and Foreign Commerce,
demonstrates that the EPA's interpretation of the section 231(a)(2)(A)
language as set forth here in support of the Agency's section 231
finding (which is the same as its interpretation of the parallel
language in section 202(a) as explained in the 2009 Endangerment
Finding), is fully consistent with Congress' intention in crafting
these provisions. See H.R. Rep. 95-294 (1977),
[[Page 37771]]
as reprinted in 4 A Legislative History of the Clean Air Act Amendments
of 1977 (1978) at 2465 (hereinafter LH).\68\
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\68\ The committee explained that its action addressed not only
section 211(c)(1)(A) but rather the entire proposal, and would thus
apply its interpretation to all other sections of the Act relating
to public health protection. 4 LH at 2516. It also noted that it had
used the same basic formulation in section 202 and section 231, as
well as in other sections. Id. at 2517.
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The legislative history clearly indicates that the House Committee
believed the Ethyl Corp. decisions posed several ``crucial policy
questions'' regarding the protection of public health and welfare. H.R.
Rep. 95-294 at 48, 4 LH at 2515.\69\ The following paragraphs summarize
the en banc decision in Ethyl Corp. v. EPA and describe how the House
Committee revised the endangerment language in the 1977 amendments to
the CAA to serve several purposes consistent with that decision. In
particular, the language: (1) Emphasizes the preventive or
precautionary nature of the CAA \70\; (2) authorizes the Administrator
to reasonably project into the future and weigh risks; (3) assures the
consideration of the cumulative impact of all sources; (4) instructs
that the health of susceptible individuals, as well as healthy adults,
should be part of the analysis; and (5) indicates an awareness of the
uncertainties and limitations in information available to the
Administrator. H.R. rep. 95-294 at 49-50, 4 LH 2516-17.\71\
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\69\ The Supreme Court recognized that the current language in
section 202(a)(1), which uses the same formulation as that in
section 231(a)(2)(A), is ``more protective'' than the 1970 version
that was similar to the section 211 language before the D.C. Circuit
in Ethyl Corp. Massachusetts v. EPA, 549 U.S. at 506, fn 7.
\70\ See H.R. Rep. 95-294 at 49, 4 LH at 2516 (``To emphasize
the preventive or precautionary nature of the Act, i.e. to assure
that regulatory action can effectively prevent harm before it
occurs'').
\71\ Congress also standardized this language across the various
sections of the CAA which address emissions from both stationary and
mobile sources. H.R. Rep. 95-294 at 50, 4 LH at 2517; section 401 of
the CAA Amendments of 1977.
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In revising the statutory language, Congress relied heavily on the
en banc decision in Ethyl Corp. v. EPA, which reversed a 3-judge panel
opinion regarding an EPA rule restricting the content of lead in leaded
gasoline.\72\ After reviewing the relevant facts and law, the full
court evaluated the statutory language at issue to see what level of
``certainty [was] required by the Clean Air Act before EPA may act.''
541 F.2d at 7.
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\72\ At the time of the 1973 rules requiring the reduction of
lead in leaded gasoline, section 211(c)(1)(A) of the CAA stated that
the Administrator may promulgate regulations that: ``Control or
prohibit the manufacture, introduction into commerce, offering for
sale, or sale of any fuel or fuel additive for use in a motor
vehicle or motor vehicle engine (A) if any emissions product of such
fuel or fuel additive will endanger the public health or welfare * *
*.'' CAA 211(c)(1)(A) (1970).
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The petitioners argued that the statutory language ``will
endanger'' required proof of actual harm, and that the actual harm had
to come from emissions from the fuels in and of themselves. Id. at 12,
29. The en banc court rejected this approach, finding that the term
``endanger'' allowed the Administrator to act when harm is threatened,
and did not require proof of actual harm. Id. at 13. ``A statute
allowing for regulation in the face of danger is, necessarily, a
precautionary statute.'' Id. Optimally, the court held, regulatory
action would not only precede, but prevent, a perceived threat. Id.
The court also rejected petitioner's argument that any threatened
harm must be ``probable'' before regulation was authorized.
Specifically, the court recognized that danger ``is set not by a fixed
probability of harm, but rather is composed of reciprocal elements of
risk and harm, or probability and severity.'' Id. at 18. Next, the
court held that the EPA's evaluation of risk is necessarily an exercise
of judgment, and that the statute did not require a factual finding.
Id. at 24. Thus, ultimately, the Administrator must ``act, in part on
`factual issues,' but largely `on choices of policy, on an assessment
of risks, [and] on predictions dealing with matters on the frontiers of
scientific knowledge * * *.'' Id. at 29 (citations omitted). Finally,
the en banc court agreed with the EPA that even without the language in
section 202(a) (which is also in section 231(a)(2)(A)) regarding
``cause or contribute to,'' it was appropriate for the EPA to consider
the cumulative impact of lead from numerous sources, not just the fuels
being regulated under section 211(c). Id. at 29-31.
The dissent in the original Ethyl Corp. decision and the en banc
opinion were of ``critical importance'' to the House Committee which
proposed the revisions to the endangerment language in the 1977
amendments to the CAA. H.R. Rep. 95-294 at 48, 4 LH at 2515. The
Committee addressed those questions with the language that now appears
in section 231(a)(2)(A) and several other CAA provisions--``emission of
any air pollutant * * * which in [the Administrator's] judgment causes,
or contributes to, air pollution which may reasonably be anticipated to
endanger public health or welfare.''
As noted above in section III.A.1, the phrase ``in [her] judgment''
calls for the Administrator to make a comparative assessment of risks
and projections of future possibilities, consider uncertainties, and
extrapolate from limited data. Thus, the Administrator must balance the
likelihood of effects with the severity of the effects in reaching her
judgment. The Committee emphasized that the Administrator's exercise of
``judgment'' \73\ may include making projections, assessments and
estimates that are reasonable, as opposed to a speculative or ``
`crystal ball' inquiry.'' Moreover, procedural safeguards apply to the
exercise of judgment, and final decisions are subject to judicial
review. Also, the phrase ``in [her] judgment'' modifies both the
phrases ``cause and contribute'' and ``may reasonably be anticipated,''
as discussed above. H.R. Rep. 95-294 at 50-51, 4 LH at 2517-18.
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\73\ Throughout this Notice under CAA section 231, as throughout
the previous Notices concerning the 2009 Endangerment Finding under
section 202, the judgments on endangerment and cause or contribute
are described as a finding or findings. This is for ease of
reference only, and is not intended to imply that the
Administrator's judgment is solely a fact finding exercise; rather,
the Administrator's exercise of judgment is to consider and weigh
multiple factors when applying the scientific information to the
statutory criteria.
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As the Committee further explained, the phrase ``may reasonably be
anticipated'' points the Administrator in the direction of assessing
current and future risks rather than waiting for proof of actual harm.
This phrase is also intended to instruct the Administrator to consider
the limitations and difficulties inherent in information on public
health and welfare. H.R. Rep. 95-294 at 51, 4 LH at 2518.\74\
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\74\ Thus, the statutory language does not require that the EPA
prove the effects of climate change ``beyond a reasonable doubt.''
Indeed, such an approach is inconsistent with the concepts of
reasonable anticipation and endangerment embedded in the statute.
See also CRR, 684 F.3d at 121-122.
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Finally, the phrase ``cause or contribute'' ensures that all
sources of the contaminant which contribute to air pollution are
considered in the endangerment analysis (e.g., not a single source or
category of sources). It is also intended to require the Administrator
to consider all sources of exposure to a pollutant (for example, food,
water, and air) when determining risk. Id.
3. Additional Considerations for the Cause or Contribute Analysis
By instructing the Administrator to consider whether emissions of
an air pollutant cause or contribute to air pollution, the statute is
clear that she need not find that emissions from any one sector or
class of sources are the sole or even the major part of an air
pollution problem. The use of the term
[[Page 37772]]
contribute clearly indicates a lower threshold than the sole or major
cause.
Moreover, like the section 202(a) language that governed the 2009
Endangerment Finding, the statutory language in section 231(a)(2)(A)
does not contain a modifier on its use of the term ``contribute.''
Unlike other CAA provisions, it does not require ``significant''
contribution. Compare, e.g., CAA sections 111(b); 213(a)(2), (4).
Congress made it clear that the Administrator is to exercise her
judgment in determining contribution, and authorized regulatory
controls to address air pollution even if the air pollution problem
results from a wide variety of sources. While the endangerment test
looks at the entire air pollution problem and the risks it poses, the
cause or contribute test is designed to authorize the EPA to identify
and then address what may well be many different sectors, classes, or
groups of sources that are each part of the problem.
As explained for the 2009 Endangerment Finding, the D.C. Circuit
has discussed the concept of contribution in the CAA, and its case law
supports the EPA's interpretation that the level of contribution need
not be significant. 74 FR 66542, December 15, 2009. In Catawba County
v. EPA, 571 F.3d 20 (D.C. Cir. 2009), the court upheld EPA's PM[2.5]
attainment and nonattainment designation decisions, analyzing CAA
section 107(d), which requires EPA to designate an area as
nonattainment if it ``contributes to ambient air quality in a nearby
area'' not attaining the national ambient air quality standards. Id. at
35. The court noted that it had previously held that the term
``contributes'' is ambiguous in the context of CAA language. See EDF v.
EPA, 82 F.3d 451, 459 (D.C. Cir. 1996). ``[A]mbiguities in statutes
within an agency's jurisdiction to administer are delegations of
authority to the agency to fill the statutory gap in reasonable
fashion.'' 571 F.3d at 35 (citing Nat'l Cable & Telecomms. Ass'c v.
Brand X Internet Servs, 545 U.S. 967, 980 (2005)). The court then
proceeded to consider and reject petitioners' argument that the verb
``contributes'' in CAA section 107(d) necessarily connotes a
significant causal relationship. Specifically, the D.C. Circuit again
noted that the term is ambiguous, leaving it to EPA to interpret in a
reasonable manner. In the context of this discussion, the court noted
that ``a contribution may simply exacerbate a problem rather than cause
it * * *.'' 571 F.3d at 39.
This is consistent with the D.C. Circuit's discussion of the
concept of contribution in the context of CAA section 213 and rules for
nonroad vehicles in Bluewater Network v. EPA, 370 F.3d 1 (D.C. Cir.
2004). In that case, industry argued that section 213(a)(3) requires a
finding of a significant contribution before the EPA can regulate,
while the EPA's view was that the CAA requires a finding only of
contribution. Id. at 13. Section 213(a)(3), like section 231(a)(2)(A),
is triggered by a finding that certain sources ``cause, or contribute
to,'' air pollution, while an adjacent provision, section 213(a)(2), is
triggered by a finding of a ``significant'' contribution. The court
looked at the ``ordinary meaning of `contribute' '' when upholding the
EPA's reading. After referencing dictionary definitions of
``contribute,'' the court also noted that ``[s]tanding alone, the term
has no inherent connotation as to the magnitude or importance of the
relevant `share' in the effect; certainly it does not incorporate any
`significance' requirement.'' 370 F.3d at 13.\75\ The court found that
the bare ``contribute'' language invests the Administrator with
discretion to exercise judgment regarding what constitutes a sufficient
contribution for the purpose of making a cause or contribute finding.
Id. at 14.\76\
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\75\ Specifically, the decision noted that `` `contribute' means
simply `to have a share in any act or effect,' Webster's Third New
International Dictionary 496 (1993), or `to have a part or share in
producing,' 3 Oxford English Dictionary 849 (2d ed. 1989).'' Id. at
13.
\76\ The court explained, ``[t]he repeated use of the term
`significant' to modify the contribution required for all nonroad
vehicles, coupled with the omission of this modifier from the
`cause, or contribute to' finding required for individual categories
of new nonroad vehicles, indicates that Congress did not intend to
require a finding of `significant contribution' for individual
vehicle categories.'' Id. at 13.
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Like the statutory language considered in Catawba County and
Bluewater Network, as well as the section 202(a) language that governed
the Agency's previous findings for GHGs emitted by other types of
mobile sources, section 231(a)(2)(A) refers to contribution and does
not specify that the contribution must be significant before an
affirmative finding can be made. To be sure, any finding of a
``contribution'' requires some threshold to be met; a truly trivial or
de minimis ``contribution'' might not count as such. The Administrator
therefore has ample discretion in exercising her reasonable judgment
and determining whether, under the circumstances presented, the cause
or contribute criterion has been met.\77\ As noted above, in addressing
provisions in section 202(a), the D.C. Circuit has explained that the
Act at the endangerment finding step did not require the EPA to
identify a precise numerical value or ``a minimum threshold of risk or
harm before determining whether an air pollutant endangers.'' CRR, 684
F.3d at 122-123. Accordingly, EPA ``may base an endangerment finding on
`a lesser risk of greater harm . . . or a greater risk of lesser harm'
or any combination in between.'' Id. (quoting Ethyl Corp., 541 F.2d at
18). Recognizing the substantial record of empirical data and
scientific evidence that the EPA relied upon in the 2009 Endangerment
Finding, the court determined that its ``failure to distill this ocean
of evidence into a specific number at which greenhouse gases cause
`dangerous' climate change is a function of the precautionary thrust of
the CAA and the multivariate and sometimes uncertain nature of climate
science, not a sign of arbitrary or capricious decision-making.'' Id.
at 123. As the language in section 231(a)(2)(A) is analogous to that in
section 202(a), it is clearly reasonable to apply this interpretation
to the endangerment determination under section 231(a)(2)(A). Moreover,
the logic underlying this interpretation supports the general principle
that under CAA section 231 the EPA is not required to identify a
specific minimum threshold of contribution from potentially subject
source categories in determining whether their emissions ``cause or
contribute'' to the endangering air pollution. The reasonableness of
this principle is further supported by the fact that section 231 does
not impose on the EPA a requirement to find that such contribution is
``significant,'' let alone the sole or major cause of the endangering
air pollution. This context further supports the EPA's interpretation
that section 231(a)(2)(A) requires some level of contribution that,
while exceeding de minimis or trivial thresholds, does not need to rise
to a pre-determined numerical level of significance.
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\77\ Section V discusses the evidence in this case that supports
the proposed finding of contribution. The EPA need not determine at
this time the circumstances in which emissions would be trivial or
de minimis and would not warrant a finding of contribution.
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In addition, when exercising her judgment in making a cause or
contribute determination, the Administrator not only considers the
cumulative impact, but also looks at the totality of the circumstances
(e.g., the air pollutant, the air pollution, the nature of the
endangerment, the type or classes of sources at issue, the number of
sources in the source sector or class, and the number and type of other
source sectors or categories that may emit the air
[[Page 37773]]
pollutant) when determining whether the emissions ``justify
regulation'' under the CAA. See Catawba County, 571 F.3d at 39
(discussing EPA's interpretation of the term ``contribute'' under CAA
Sec. 107(d) and finding it reasonable for the agency to adopt a
totality of the circumstances approach); see also 74 FR at 66542,
(December 15, 2009). Further discussion of this issue can be found in
sections IV and V of this preamble.
B. Air Pollutant, Public Health and Welfare
The CAA defines both ``air pollutant'' and ``welfare.'' Air
pollutant is defined as: ``Any air pollution agent or combination of
such agents, including any physical, chemical, biological, radioactive
(including source material, special nuclear material, and byproduct
material) substance or matter which is emitted into or otherwise enters
the ambient air. Such term includes any precursors to the formation of
any air pollutant, to the extent the Administrator has identified such
precursor or precursors for the particular purpose for which the term
`air pollutant' is used.'' CAA section 302(g). Greenhouse gases fit
well within this capacious definition. See Massachusetts v. EPA, 549
U.S. at 532. They are ``without a doubt'' physical chemical substances
emitted into the ambient air. Id. at 529. Section V below contains
further discussion of the ``air pollutant'' for purposes of this
section 231 proposed contribution finding, which uses the same
definition of air pollutant as the EPA adopted for purposes of the 2009
Endangerment Finding.
Regarding ``welfare,'' the CAA states that ``[a]ll language
referring to effects on welfare includes, but is not limited to,
effects on soils, water, crops, vegetation, man-made materials,
animals, wildlife, weather, visibility, and climate, damage to and
deterioration of property, and hazards to transportation, as well as
effects on economic values and on personal comfort and well-being,
whether caused by transformation, conversion, or combination with other
air pollutants.'' CAA section 302(h). This definition is quite broad.
Importantly, it is not an exclusive list due to the use of the term
``includes, but is not limited to, * * *.'' Effects other than those
listed here may also be considered effects on welfare.
Moreover, the terms contained within the definition are themselves
expansive. For example, deterioration to property could include damage
caused by extreme weather events. Effects on vegetation could include
impacts from changes in temperature and precipitation as well as from
the spreading of invasive species or insects. Prior welfare effects
evaluated by the EPA in other contexts include impacts on vegetation,
as well as reduced visibility, changes in nutrient balance and acidity
of the environment, soiling of buildings and statues, and erosion of
building materials. See, e.g., Final Secondary National Ambient Air
Quality Standards for Oxides of Nitrogen and Sulfur, 77 FR 20218, April
3, 2012; Control of Emissions from Nonroad Large Spark Ignition Engines
and Recreational Engines (Marine and Land-Based), 67 FR 68242, November
8, 2002; Final Heavy-Duty Engine and Vehicle Standards and Highway
Diesel Sulfur Control Requirements, 66 FR 5002, January 18, 2001.
Although the CAA defines ``effects on welfare'' as discussed above,
there are no definitions of ``public health'' or ``public welfare'' in
the Clean Air Act. The Supreme Court has discussed the concept of
``public health'' in the context of whether costs can be considered
when setting National Ambient Air Quality Standards. Whitman v.
American Trucking Ass'n, 531 U.S. 457 (2001). In Whitman, the Court
imbued the term with its most natural meaning: ``The health of the
public.'' Id. at 466. When considering public health, the EPA has
looked at morbidity, such as impairment of lung function, aggravation
of respiratory and cardiovascular disease, and other acute and chronic
health effects, as well as mortality. See, e.g., Final National Ambient
Air Quality Standard for Ozone, 73 FR 16436, March 27, 2008.
IV. The Proposed Endangerment Finding Under CAA Section 231
This section describes the Administrator's proposed endangerment
finding under CAA section 231(a)(2) and its basis. Beginning with the
air pollution under consideration, the Administrator is proposing to
use the same definition of the ``air pollution'' under CAA section
231(a)(2) as that used under CAA section 202(a)(1), namely the mix of
six well-mixed GHGs mentioned above: CO2, methane, nitrous
oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.
As described in section IV.A below, it is the Administrator's view that
the reasons detailed in the 2009 Endangerment Finding for defining the
scope and nature of the air pollution to be these six well-mixed GHGs
remain valid and well-supported by the current science and are
therefore reasonable bases for adopting the same definition of ``air
pollution'' in this section 231(a)(2)(A) finding. Information from the
new scientific assessments described in section IV.B below provides
further support that the six well-mixed GHGs are the primary cause and
driver of climate change. The Administrator considered other climate-
forcing agents both in the 2009 Endangerment Finding and in this
action; however, these substances are not included in the air pollution
definition proposed in this action for the reasons discussed below in
section IV.B.4.
The Administrator is proposing to find, for purposes of CAA section
231(a)(2)(A), that elevated concentrations of the six well-mixed GHGs
constitute air pollution that endangers both the public health and the
public welfare of current and future generations. The Administrator's
view is that the body of scientific evidence amassed in the record for
the 2009 Endangerment Finding compellingly supports an endangerment
finding under CAA section 231(a). Information from the new scientific
assessments described in section IV.B below provides further support
and justification for this proposed finding.
Section IV.A below summarizes the 2009 Endangerment Finding under
CAA section 202, explains the approach EPA took in compiling an
extensive record to inform the Administrator's judgment on that
finding, and describes the recent judicial affirmation of the 2009
Endangerment Finding. Section IV.B provides a summary of new scientific
assessments that strengthen or provide further scientific evidence, in
addition to that which the Administrator relied upon in making her
prior judgment, for a finding that GHGs endanger public health and
welfare.\78\ Finally, section IV.C summarizes the Administrator's
conclusion for purposes of section 231, in light of the evidence,
analysis, and conclusions that led to the 2009 Endangerment Finding as
well as more recent evidence, that emissions of the six well-mixed GHGs
in the atmosphere endanger public health and welfare.
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\78\ While the EPA is providing a summary of newer scientific
assessments below, the EPA is also relying on the same scientific
and technical evidence discussed in the notices for the 2009
Endangerment Finding in this proposed finding for purposes of CAA
section 231. See sections III of the 2009 Proposed Endangerment
Finding and sections III and IV of the 2009 Endangerment Finding.
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A. Scientific Basis of the 2009 Endangerment Finding Under CAA Section
202(a)(1)
In the 2009 Endangerment Finding, the Administrator found that
elevated concentrations of the well-mixed GHGs in the atmosphere may
reasonably be
[[Page 37774]]
anticipated to endanger public health and welfare of current and future
generations. See, e.g., 74 FR 66516, December 15, 2009. The
Administrator reached this judgment by carefully considering a
significant body of scientific evidence and public comments submitted
to the Agency. The sections below summarize the scope and nature of the
relevant air pollution for the 2009 Endangerment Finding, as well as
the public health and welfare considerations within the finding.
1. The Definition of Air Pollution in the 2009 Endangerment Finding
The Administrator defined the scope and nature of the relevant air
pollution as the aggregate group of six key, well-mixed GHGs:
CO2, methane, nitrous oxide, hydrofluorocarbons,
perfluorocarbons, and sulfur hexafluoride.\79\ The Administrator
considered five primary reasons for focusing on this aggregate group as
the air pollution in the 2009 Endangerment Finding: (1) They share
common physical properties that influence their climate effects; (2) on
the basis of these common physical properties, they have been
determined to be the primary cause of human-induced climate change, are
the best-understood driver of climate change, and are expected to
remain the key driver of future climate change; (3) they are the common
focus of climate change science research and policy analyses and
discussions; (4) using the combined mix of these gases as the
definition (versus an individual gas-by-gas approach) is consistent
with the science, because risks and impacts associated with GHG-induced
climate change are not assessed on an individual gas-by-gas basis; and
(5) using the combined mix of these gases is consistent with past EPA
practice, where separate substances from different sources, but with
common properties, may be treated as a class (e.g., oxides of nitrogen,
particulate matter, volatile organic compounds).\80\
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\79\ 74 FR 66516, December 15, 2009.
\80\ 74 FR 66517 to 66519, December 15, 2009.
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The common physical properties these six GHGs share that are
relevant to the climate change problem include the following: All are
long-lived in the atmosphere; \81\ all become globally well mixed in
the atmosphere, resulting in similar GHG concentrations around the
globe regardless of geographic location of emissions; all trap outgoing
heat that would otherwise escape to space; and all are directly emitted
as GHGs rather than becoming a GHG in the atmosphere after emission of
a precursor gas. The Administrator acknowledged that other
anthropogenic climate forcers also play a role in climate change but
for various scientific and policy reasons, these substances were not
included in the air pollution definition.\82\
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\81\ We use ``long-lived'' here to mean that the gas has a
lifetime in the atmosphere sufficient to become globally well-mixed
throughout the entire atmosphere, which requires a minimum
atmospheric lifetime of about one year. IPCC also refers to these
six greenhouse gases as long-lived. According to the most recent
IPCC Fifth Assessment Report (2014), methane has an atmospheric
lifetime of about 12 years. One of the most commonly used
hydrofluorocarbons (HFC-134a) has a lifetime of about 13 years.
Nitrous oxide has a lifetime of around 130 years; sulfur
hexafluoride over 3,000 years; and some perfluorocarbons up to
10,000 to 50,000 years. CO2 is sometimes approximated as
having a lifetime of roughly 100 years, but for a given amount of
CO2 emitted a better description is that some fraction of
the atmospheric increase in concentration is quickly absorbed by the
oceans and terrestrial vegetation, some fraction of the atmospheric
increase will only slowly decrease over a number of years, and a
small portion of the increase will remain for many centuries or
more.
\82\ 74 FR 66519 to 66521, December 15, 2009.
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As explained in more detail in the 2009 Endangerment Finding, the
EPA made the judgment that the scientific evidence is compelling that
elevated concentrations of heat-trapping GHGs are the root cause of
recently observed climate change and that the scientific record showed
that most of the observed increase in global average temperatures since
the mid-20th century is very likely due to the observed increase in
anthropogenic GHG concentrations. The attribution of observed climate
change to anthropogenic activities was based on multiple lines of
evidence.\83\ The first line of evidence arises from our basic physical
understanding of the effects of changing concentrations of GHGs,
natural factors, and other human impacts on the climate system. The
second line of evidence arises from indirect, historical estimates of
past climate changes that suggest that the changes in global surface
temperature over the last several decades are unusual. The third line
of evidence arises from the use of computer-based climate models to
simulate the likely patterns of response of the climate system to
different forcing mechanisms (both natural and anthropogenic).
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\83\ 74 FR 66518, December 15, 2009.
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2. Public Health Impacts Detailed in the 2009 Endangerment Finding
Climate change resulting from anthropogenic GHG emissions threatens
multiple aspects of public health.\84\ In determining that the well-
mixed GHG air pollution is reasonably anticipated to endanger public
health for current and future generations, the Administrator noted her
view that climate change can increase the risk of morbidity and
mortality.\85\ In making that public health finding, the Administrator
considered direct temperature effects, air quality effects, the
potential for changes in vector-borne diseases, and the potential for
changes in the severity and frequency of extreme weather events. In
addition, the Administrator considered whether and how susceptible
populations may be particularly at risk. As explained in more detail in
the 2009 Endangerment Finding, with respect to direct temperature
effects, by raising average temperatures, climate change increases the
likelihood of heat waves, which are associated with increased deaths
and illnesses. Climate change is also expected to lead to reductions in
cold-related mortality. The 2009 Endangerment Finding, while noting
uncertainty about how heat and cold related mortality would change in
the future, also pointed to a USGCRP assessment report discussion that
increases in heat-related mortality due to global warming in the United
States was unlikely to be compensated for by decreases in cold-related
mortality (74 FR 66525, December 15, 2009). With regard to air quality
effects, climate change is expected to increase ozone pollution over
broad areas of the country, including large metropolitan population
centers, and thereby increase the risks of respiratory infection,
aggravation of asthma, and premature death. Other public health threats
stem from the potential for increased deaths, injuries, infectious and
waterborne diseases, stress-related disorders, and other adverse
effects associated with increased hurricane intensity and increased
frequency of intense storms and heavy precipitation associated with
climate change. In addition, climate change is expected to be
associated with an increase in the spread of food-, water-, and vector-
borne diseases in susceptible populations. Climate change also has the
potential to change aeroallergen production (for example, through
lengthening the growing season for allergen-producing plants), and
subsequent human exposures could increase allergenic illnesses.
Children, the elderly, and the poor are among the most vulnerable to
climate-related health effects.
---------------------------------------------------------------------------
\84\ 74 FR 66524 to 66530, December 15, 2009.
\85\ 74 FR 66524, December 15, 2009.
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3. Public Welfare Impacts Detailed in the 2009 Endangerment Finding
Climate change resulting from anthropogenic GHG emissions also
threatens multiple aspects of public welfare.\86\ In determining that
the well-
[[Page 37775]]
mixed GHG air pollution is reasonably anticipated to endanger public
welfare for current and future generations, the Administrator
considered the multiple pathways by which GHG air pollution and
resultant climate change affect public welfare by evaluating the
numerous and far-ranging risks to food production and agriculture;
forestry; water resources; sea level rise and coastal areas; energy,
infrastructure, and settlements; and ecosystems and wildlife. The
Administrator also considered impacts on the U.S. population from
climate change effects occurring outside of the United States. As
explained in more detail in the 2009 Endangerment Finding, the
potential serious adverse impacts of extreme events, such as wildfires,
flooding, drought, and extreme weather conditions provided strong
support for the determination. Climate change is expected to place
large areas of the country at serious risk of reduced water supplies,
increased water pollution, and increased occurrence of extreme events
such as floods and droughts. Coastal areas are expected to face
increased risks from storm and flooding damage to property, as well as
adverse impacts from rising sea level such as land loss due to
inundation, erosion, wetland submergence and habitat loss. Climate
change is expected to result in an increase in peak electricity demand,
and extreme weather from climate change threatens energy,
transportation, and water resource infrastructure. Climate change may
exacerbate existing environmental pressures in certain settlements,
particularly in Alaskan indigenous communities. Climate change is also
very likely to fundamentally change U.S. ecosystems over the 21st
century and to lead to predominantly negative consequences for
biodiversity, ecosystem goods and services, and wildlife. Though there
may be some benefits for agriculture and forestry in the next few
decades, the body of evidence points towards increasing risks of net
adverse impacts on U.S. food production, agriculture and forest
productivity as average temperature continues to rise. Looking across
all sectors discussed above, the risk and the severity of adverse
impacts on public welfare are expected to increase over time. Lastly,
these impacts are global and may exacerbate problems outside the United
States that raise humanitarian, trade, and national security issues for
the United States.
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\86\ 74 FR 66530 to 66536, December 15, 2009.
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4. The Science Upon Which the Agency Relied
As outlined in section III.A of the 2009 Endangerment Finding,\87\
the EPA's approach to providing the technical and scientific
information to inform the Administrator's judgment regarding the
question of whether GHGs endanger public health and welfare was to rely
primarily upon the recent, major assessments by the USGCRP, the IPCC,
and the NRC. These assessments addressed the scientific issues that the
EPA was required to examine, were comprehensive in their coverage of
the GHG and climate change issues, and underwent rigorous and exacting
peer review by the expert community, as well as rigorous levels of U.S.
government review, in which the EPA took part. Primary reliance on the
major scientific assessments provided assurance that the Administrator
was basing her judgment on the best available, well-vetted science that
reflected the consensus of the climate science research community. The
major findings of the USGCRP, IPCC, and NRC assessments supported the
Administrator's determination that elevated concentrations of GHGs in
the atmosphere may reasonably be anticipated to endanger the public
health and welfare of current and future generations. The EPA presented
this scientific support at length in the comprehensive record for the
2009 Endangerment Finding. Relevant sections of documents from the 2009
Endangerment Finding record have been placed in the docket for this
proposed finding under CAA section 231.
---------------------------------------------------------------------------
\87\ 74 FR 66510 to 66512, December 15, 2009.
---------------------------------------------------------------------------
The EPA then reviewed ten administrative petitions for
reconsideration of the Endangerment Finding in 2010.\88\ In the
Reconsideration Denial, the Administrator denied those petitions on the
basis of the Petitioners' failure to provide substantial support for
their argument that the EPA should revise the Endangerment Finding and
their objections' lack of ``central relevance'' to the Finding. The EPA
prepared an accompanying three-volume Response to Petitions document to
provide additional information, often more technical in nature, in
response to the arguments, claims, and assertions by the Petitioners to
reconsider the Endangerment Finding.\89\
---------------------------------------------------------------------------
\88\ Administrative petitions are available from http://www.epa.gov/climatechange/endangerment/petitions.html (last accessed
May 12, 2015), and in the docket for the 2009 Endangerment Finding:
EPA-HQ-OAR-2009-017.
\89\ U.S. EPA, 2010: Denial of the Petitions to Reconsider the
Endangerment and Cause or Contribute Findings for Greenhouse Gases
Under section 202(a) of the Clean Air Act, 75 FR 49557 (August 13,
2010) (``Reconsideration Denial''). In that notice, the EPA
thoroughly considered the scientific and technical information
relevant to the petitions. In addition to the other information
discussed in the present notice, the EPA is also relying on the
scientific and technical evidence discussed in that prior notice for
purposes of its proposed determination under CAA section 231. See
section III of the Reconsideration Denial.
---------------------------------------------------------------------------
The 2009 Endangerment Finding and the 2010 Reconsideration Denial
were challenged in a lawsuit before the U.S. Court of Appeals for the
D.C. Circuit.\90\ On June 26, 2012, the Court upheld the Endangerment
Finding and the Reconsideration Denial, ruling that the Finding
(including the Reconsideration Denial) was not arbitrary or capricious,
was consistent with the U.S. Supreme Court's decision in Massachusetts
v. EPA (which affirmed the EPA's authority to regulate greenhouse
gases) \91\ and the text and structure of the CAA, and was adequately
supported by the administrative record.\92\ The Court also agreed with
the EPA that the Petitioners had ``not provided substantial support for
their argument that the Endangerment Finding should be revised.'' \93\
The Court found that the EPA had based its decision on ``substantial
scientific evidence,'' observing that ``EPA's scientific evidence of
record included support for the proposition that greenhouse gases trap
heat on earth that would otherwise dissipate into space; that this
`greenhouse effect' warms the climate; that human activity is
contributing to increased atmospheric levels of greenhouse gases; and
that the climate system is warming,'' as well as providing extensive
scientific evidence for EPA's determination that anthropogenically
induced climate change threatens both public health and welfare.\94\
The court further noted that the EPA's reliance on assessments was
consistent with the methods decision-makers often use to make a
science-based judgment.\95\ Moreover, the Court supported the EPA's
reliance on the major scientific assessment reports conducted by
USGCRP, IPCC, and NRC and found:
---------------------------------------------------------------------------
\90\ Coalition for Responsible Regulation, Inc. v. Environmental
Protection Agency, 684 F.3d 102 (D.C. Cir. 2012),), reh'g en banc
denied, 2012 U.S. App. LEXIS 25997, 26313, 26315 (D.C. Cir. 2012)
(CRR).
\91\ 549 U.S. 497 (2007).
\92\ CRR, 684 F.3d at 117-27.
\93\ Id. at 125
\94\ Id. at 120-121.
\95\ Id. at 121
The EPA evaluated the processes used to develop the various
assessment reports, reviewed their contents, and considered the
depth of the scientific consensus the reports
[[Page 37776]]
represented. Based on these evaluations, the EPA determined the
assessments represented the best source material to use in deciding
whether GHG emissions may be reasonably anticipated to endanger
public health or welfare. . . . It makes no difference that much of
the scientific evidence in large part consisted of ``syntheses'' of
individual studies and research. Even individual studies and
research papers often synthesize past work in an area and then build
upon it. This is how science works. The EPA is not required to re-
prove the existence of the atom every time it approaches a
scientific question.\96\
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\96\ Id. at 120.
In addition, the EPA's reliance on the major assessments to inform
the Administrator's judgment allowed for full and explicit recognition
of scientific uncertainty regarding the endangerment posed by the
atmospheric buildup of GHGs. The Administrator considered the fact that
``some aspects of climate change science and the projected impacts are
more certain than others.'' \97\ The D.C. Circuit subsequently noted
that ``the existence of some uncertainty does not, without more,
warrant invalidation of an endangerment finding.'' \98\
---------------------------------------------------------------------------
\97\ 74 FR at 66524, December 15, 2009.
\98\ CRR, 684 F.3d at 121.
---------------------------------------------------------------------------
As noted above the Supreme Court granted some of the petitions for
certiorari that were filed, while denying others, but agreed to decide
only the question: ``Whether EPA permissibly determined that its
regulation of greenhouse gas emissions from new motor vehicles
triggered permitting requirements under the Clean Air Act for
stationary sources that emit greenhouse gases.'' \99\ Thus, the Supreme
Court did not disturb the D.C. Circuit's holding that affirmed the 2009
Endangerment Finding.
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\99\ Utility Air Reg. Group v. EPA, 134 S. Ct. 2427, 2438 (2014)
(internal marks and citations omitted). See also Virginia v. EPA,
134 S. Ct. 418 (2013), Pac. Legal Found. v. EPA, 134 S. Ct. 418
(2013), and CRR, 134 S. Ct. 468 (2013) (all denying cert.).
---------------------------------------------------------------------------
B. Recent Science Further Supports the Administrator's Judgment That
the Six Well-Mixed Greenhouse Gases Endanger Public Health and Welfare
Since the closure of the administrative record concerning the 2009
Endangerment Finding (including the denial of petitions for
reconsideration), a number of new major, peer-reviewed scientific
assessments have been released. The EPA carefully reviewed the updated
scientific conclusions in these assessments, largely to evaluate
whether they would lead the EPA in this CAA section 231(a)(2)(A)
finding to propose a different interpretation of, or place more or less
weight on, the major findings reflected in the previous assessment
reports that underpinned the Administrator's judgment that the six
well-mixed GHGs endanger public health and welfare. From its review,
the EPA finds that these new assessments are largely consistent with,
and in many cases strengthen and add to, the already compelling and
comprehensive scientific evidence detailing the role of the six well-
mixed GHGs in driving climate change, detailed in the 2009 Endangerment
Finding. Therefore, the new scientific assessments do not provide any
reasonable basis on which to propose under CAA section 231(a)(2)(A) a
different conclusion than the one the EPA reached in 2009 under CAA
section 202(a). Rather, they provide further support for this proposed
finding under section 231. In particular, the new assessments discussed
in this preamble provide additional detail regarding public health
impacts, particularly on groups and people at certain lifestages
especially vulnerable to climate change including children, the
elderly, low-income communities and individuals, indigenous groups, and
communities of color.
The subsections below present brief summaries of the relevant key
findings from the new major peer-reviewed scientific assessments, which
include the following:
IPCC's 2013-2014 Fifth Assessment Report (AR5) \100\
---------------------------------------------------------------------------
\100\ IPCC, 2013: Climate Change 2013: The Physical Science
Basis. Contribution of Working Group I to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change [Stocker,
T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A.
Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge
University Press, 1535 pp, doi:10.1017/CBO9781107415324; IPCC, 2014:
Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A:
Global and Sectoral Aspects. Contribution of Working Group II to the
Fifth Assessment Report of the Intergovernmental Panel on Climate
Change [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D.
Mastrandrea, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C.
Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R.
Mastrandrea, and L.L. White (eds.)]. Cambridge University Press,
1132 pp; IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and
Vulnerability. Part B: Regional Aspects. Contribution of Working
Group II to the Fifth Assessment Report of the Intergovernmental
Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D.
Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O.
Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S.
MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge
University Press, 688 pp; and IPCC, 2014: Climate Change 2014:
Mitigation of Climate Change. Contribution of Working Group III to
the Fifth Assessment Report of the Intergovernmental Panel on
Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E.
Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P.
Eickemeier, B. Kriemann, J. Savolainen, S. Schl[ouml]mer, C. von
Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge University
Press, 1435 pp.
---------------------------------------------------------------------------
IPCC's 2012 ``Special Report on Managing the Risks of
Extreme Events and Disasters to Advance Climate Change Adaptation''
(SREX) \101\
---------------------------------------------------------------------------
\101\ IPCC, 2012: Managing the Risks of Extreme Events and
Disasters to Advance Climate Change Adaptation. A Special Report of
Working Groups I and II of the Intergovernmental Panel on Climate
Change [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken,
K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen,
M. Tignor, and P.M. Midgley (eds.)]. Cambridge University Press, 582
pp.
---------------------------------------------------------------------------
USGCRP's 2014 ``Climate Change Impacts in the United
States: the Third National Climate Assessment'' (NCA3) \102\
---------------------------------------------------------------------------
\102\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, 841 pp.
---------------------------------------------------------------------------
NRC's 2010 ``Ocean Acidification: A National Strategy to
Meet the Challenges of a Changing Ocean'' (Ocean Acidification) \103\
---------------------------------------------------------------------------
\103\ NRC, 2010: Ocean Acidification: A National Strategy to
Meet the Challenges of a Changing Ocean. The National Academies
Press, 188 pp.
---------------------------------------------------------------------------
NRC's 2011 ``Climate Change, the Indoor Environment, and
Health'' (Indoor Environment) \104\
---------------------------------------------------------------------------
\104\ NRC Institute of Medicine, 2011: Climate Change, the
Indoor Environment, and Health. Washington, DC: The National
Academies Press, 272 pp.
---------------------------------------------------------------------------
NRC's 2011 ``Report on Climate Stabilization Targets:
Emissions, Concentrations, and Impacts over Decades to Millennia''
(Climate Stabilization Targets) \105\
---------------------------------------------------------------------------
\105\ NRC 2011: Climate Stabilization Targets: Emissions,
Concentrations, and Impacts over Decades to Millennia. The National
Academies Press, 298 pp.
---------------------------------------------------------------------------
NRC's 2011 ``National Security Implications for U.S. Naval
Forces'' (National Security Implications) \106\
---------------------------------------------------------------------------
\106\ NRC, 2011: National Security Implications of Climate
Change for U.S. Naval Forces. The National Academies Press, 226 pp.
---------------------------------------------------------------------------
NRC's 2011 ``Understanding Earth's Deep Past: Lessons for
Our Climate Future'' (Understanding Earth's Deep Past) \107\
---------------------------------------------------------------------------
\107\ NRC, 2011: Understanding Earth's Deep Past: Lessons for
Our Climate Future. The National Academies Press, 212 pp.
---------------------------------------------------------------------------
NRC's 2012 ``Sea Level Rise for the Coasts of California,
Oregon, and Washington: Past, Present, and Future'' (Sea Level Rise)
\108\
---------------------------------------------------------------------------
\108\ NRC, 2012: Sea-Level Rise for the Coasts of California,
Oregon, and Washington: Past, Present, and Future. The National
Academies Press, 201 pp.
---------------------------------------------------------------------------
NRC's 2013 ``Climate and Social Stress: Implications for
Security Analysis'' (Climate and Social Stress) \109\
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\109\ NRC, 2013: Climate and Social Stress: Implications for
Security Analysis. The National Academies Press, 280 pp.
---------------------------------------------------------------------------
[[Page 37777]]
NRC's 2013 ``Abrupt Impacts of Climate Change'' (Abrupt
Impacts) \110\
---------------------------------------------------------------------------
\110\ NRC, 2013: Abrupt Impacts of Climate Change: Anticipating
Surprises. The National Academies Press, 250 pp.
---------------------------------------------------------------------------
NRC's 2014 ``The Arctic in the Anthropocene: Emerging
Research Questions'' (Arctic) \111\.
---------------------------------------------------------------------------
\111\ NRC, 2014: The Arctic in the Anthropocene: Emerging
Research Questions. The National Academies Press, 220 pp.
---------------------------------------------------------------------------
1. More Recent Evidence That Elevated Atmospheric Concentrations of the
Six Greenhouse Gases Are the Root Cause of Observed Climate Change
The EPA has carefully reviewed the recent assessments regarding
elevated concentrations of the six well-mixed GHGs in the atmosphere.
The EPA finds that the new assessments of the IPCC, USGCRP, and NRC
support and strengthen the science underlying the 2009 Endangerment
Finding that the six well-mixed GHGs are the root cause of recently
observed climate change. Key findings are described briefly here.
According to the IPCC AR5, observations of the Earth's globally
averaged combined land and ocean surface temperature over the period
1880 to 2012 show a warming of 0.85 [0.65 to 1.06] degrees Celsius or
1.53 [1.17 to 1.91] degrees Fahrenheit.\112\ The IPCC AR5 concludes
that the global average net effect of the increase in atmospheric GHG
concentrations, plus other human activities (e.g., land use change and
aerosol emissions), on the global energy balance since 1750 has been
one of warming. This total net heating effect, referred to as
``forcing,'' is estimated to be 2.3 Watts per square meter (W/m2),
which has increased from the previous 2007 IPCC Fourth Assessment
Report (AR4) total net estimate of 1.6 Watts per square meter (W/m2)
that was referred to in the record for the 2009 Endangerment Finding.
The reasons for this increase include continued increases in GHG
concentrations, as well as reductions in the estimated negative forcing
due to aerosols. The IPCC AR5 rates the level of confidence \113\ in
their radiative forcing estimates as ``high'' for methane and ``very
high'' for CO2 and nitrous oxide.
---------------------------------------------------------------------------
\112\ ``IPCC, 2013: Summary for Policymakers. In: Climate Change
2013: The Physical Science Basis. Contribution of Working Group I to
the Fifth Assessment Report of the Intergovernmental Panel on
Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor,
S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley
(eds.)]. Cambridge University Press, 29 pp.
\113\ The IPCC expresses levels of confidence using five
qualifiers: very low, low, medium, high, and very high. These levels
are based on a qualitative evaluation of the robustness of the
evidence (considering the type, amount, quality, and consistency of
evidence such as data, mechanistic understanding, theory, models,
and expert judgment) and the degree of agreement among the findings.
---------------------------------------------------------------------------
The new assessments also have greater confidence in attributing
recent warming to human causes. The IPCC AR5 stated that it is
extremely likely (>95 percent likelihood) that human influences have
been the dominant cause of warming since the mid-20th century, which is
a stronger statement than the AR4 conclusion that it is very likely
(>90 percent likelihood) that most of the increase in temperature since
the mid-20th century was due to the increase in GHG concentrations. The
AR4 conclusion was referred to in the record for the 2009 Endangerment
Finding. In addition, the IPCC AR5 found that concentrations of
CO2 and several other of the major GHGs are higher than they
have been in at least 800,000 years. This is an increase from what was
reported in IPCC AR4, which found higher concentrations than in at
least 650,000 years.
The USGCRP NCA3 states that there is very high confidence \114\
that the global climate change of the past 50 years is primarily due to
human activities. Human activities are affecting climate through
increasing atmospheric levels of heat-trapping gases, through changing
levels of various particles that can have either a heating or cooling
influence on the atmosphere, and through activities such as land use
changes that alter the reflectivity of the Earth's surface and cause
climatic warming and cooling effects. The USGCRP concludes that
``considering all known natural and human drivers of climate since
1750, a strong net warming from long-lived greenhouse gases produced by
human activities dominates the recent climate record.'' \115\
---------------------------------------------------------------------------
\114\ The NCA expresses levels of confidence using four
qualifiers: low, medium, high, and very high. These levels are based
on the strength and consistency of the observed evidence; the skill,
range, and consistency of model projections; and insights from peer-
reviewed sources.
\115\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 741
---------------------------------------------------------------------------
These recent and strong conclusions attributing recent observed
global warming to human influence have been made despite what some have
termed a warming slowdown or ``hiatus'' over the past 15 years or so.
The IPCC AR5 notes that global mean surface temperature exhibits
substantial natural decadal and interannual variability, such that
trends based on short records are very sensitive to the beginning and
end dates and do not in general reflect long-term climate trends. As an
example, the IPCC AR5 notes that the rate of warming over the 15 year
period from 1998-2012 was less than that over the period 1951-2012.
This short term variability does not alter the long-term climate trend
that the IPCC AR5 finds after its review of independently verified
observational records: ``Each of the past three decades has been
successively warmer at the Earth's surface than all the previous
decades in the instrumental record, and the first decade of the 21st
century has been the warmest.'' 116 117
---------------------------------------------------------------------------
\116\ IPCC, 2013: Climate Change 2013: The Physical Science
Basis. Contribution of Working Group I to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change [Stocker,
T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A.
Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge
University Press, p. 161.
\117\ Furthermore, we would note that according to both NOAA and
NASA, 2014 was the warmest year in the modern instrumental record
for globally averaged surface temperature, and that the ten warmest
years, with the exception of 1998, have now occurred since 2000.
Available at http://www.giss.nasa.gov/research/news/20150116/ (last
accessed May 12, 2015).
---------------------------------------------------------------------------
The NRC Climate Stabilization Targets assessment concludes that
CO2 emissions are currently altering the atmosphere's
composition and will continue to alter Earth's climate for thousands of
years. The NRC Understanding Earth's Deep Past assessment finds that
``the magnitude and rate of the present greenhouse gas increase place
the climate system in what could be one of the most severe increases in
radiative forcing of the global climate system in Earth history.''
\118\ This assessment finds that if no emissions reductions are made
CO2 concentrations by the end of the century are projected
to increase to levels that Earth has not experienced for more than 30
million years.
---------------------------------------------------------------------------
\118\ NRC, 2011: Understanding Earth's Deep Past: Lessons for
Our Climate Future. The National Academies Press, p. 138.
---------------------------------------------------------------------------
2. More Recent Evidence That Greenhouse Gases Endanger Public Health
The EPA has carefully reviewed the key conclusions in the recent
assessments regarding human-induced climate change risks and impacts on
public health. The EPA finds that the new assessments are consistent
with or strengthen the underlying science considered in the 2009
Endangerment Finding regarding public health effects from changes in
temperature, air quality, extreme weather, and climate-sensitive
diseases and aeroallergens. These key findings are described briefly
here.
[[Page 37778]]
Regarding temperature effects, the conclusions of the assessment
literature cited in the 2009 Endangerment Finding were uncertain with
respect to the exact balance of how heat- versus cold-related mortality
will change in the future, but noted that the available evidence
suggested that the increased risk from heat would exceed the decreased
risk from cold in a warming climate. The most recent assessments now
have greater confidence that increases in heat-related mortality will
be larger than the decreases in cold-related mortality. The USGCRP NCA3
concludes that, ``While deaths and injuries related to extreme cold
events are projected to decline due to climate change, these reductions
are not expected to compensate for the increase in heat-related
deaths.'' \119\ The IPCC AR5 also notes a potential benefit of climate
change could include ``modest reductions in cold-related mortality and
morbidity in some areas due to fewer cold extremes (low confidence),''
\120\ but that, ``[o]verall, we conclude that the increase in heat-
related mortality by mid-century will outweigh gains due to fewer cold
periods.'' \121\
---------------------------------------------------------------------------
\119\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 224.
\120\ IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and
Vulnerability. Part A: Global and Sectoral Aspects. Contribution of
Working Group II to the Fifth Assessment Report of the
Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros,
D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee,
K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N.
Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)].
Cambridge University Press, p. 713.
\121\ Ibid. at p. 721.
---------------------------------------------------------------------------
Regarding air quality effects, the assessment literature cited in
the 2009 Endangerment Finding concluded that climate change is expected
to increase regional ozone pollution, with associated risks in
respiratory illnesses and premature death, but that the directional
effect of climate change on ambient particulate matter levels was less
certain. The USGCRP NCA3 similarly concludes that, ``Climate change is
projected to harm human health by increasing ground-level ozone and/or
particulate matter air pollution in some locations. . . . There is less
certainty in the responses of airborne particles to climate change than
there is about the response of ozone.'' \122\ The IPCC AR5 finds that
ozone and particulate matter have been associated with adverse health
effects in many locations in North America, and that ozone
concentrations could increase under future climate change scenarios if
emissions of precursors were held constant. For particulate matter,
both the USGCRP NCA3 and IPCC AR5 discuss increasing wildfire risk
under climate change, and explain that wildfire smoke exposure can lead
to various respiratory and cardiovascular impacts. The NRC Indoor
Environment assessment identifies potential adverse health risks
associated with climate-change induced alterations in the indoor
environment, including possible exposure to air pollutants like ozone
via changes in outdoor air quality. Other risks include potential for
alterations in indoor allergens due to climate change-related increases
in outdoor pollen levels, potential chemical exposures due to greater
use of pesticides to address changes in geographic ranges of pest
species, and dampness/mold associated symptoms and illness due to
potential flooding and water damage in buildings from projected climate
change-related increases in storm intensity and extreme precipitation
events in some regions of the United States.
---------------------------------------------------------------------------
\122\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 222.
---------------------------------------------------------------------------
Regarding extreme weather events (e.g., storms, heavy
precipitation, and, in some regions of the United States, floods and
droughts), the conclusions of the assessment literature cited in the
2009 Endangerment Finding found potential for increased deaths,
injuries, infectious and waterborne diseases, and stress-related
disorders. Similarly, the USGCRP NCA3 discusses elevated waterborne
disease outbreaks and the potential for mold contamination and degraded
indoor air quality following heavy precipitation. Other impacts include
mortality associated with flooding and impacts on mental health, such
as anxiety and post-traumatic stress disorder. The IPCC AR5 also
discusses death and injury in coastal zones and regions vulnerable to
inland flooding. The USGCRP NCA3 and the IPCC AR5 both find that
climate change may increase exposure to and health risks associated
with drought conditions, which includes impacts from wildfires, dust
storms, extreme heat events, flash flooding, degraded water quality,
reduced water quantity, and water-related diseases. The IPCC SREX
assessment projects further increases in some extreme weather and
climate events during this century, and specifically notes that changes
in extreme weather events have implications for disaster risk in the
health sector.
The effects of climate change on climate-sensitive diseases were
also cited in the 2009 Endangerment Finding, including a likely
increase in the spread of several food and water-borne pathogens among
susceptible populations, and the potential for range expansion of some
zoonotic disease carriers such as the Lyme disease-carrying tick. The
new assessment literature similarly focuses on increased exposure risk
for some diseases under climate change, finding that increasing
temperatures may expand or shift the ranges of some disease vectors
like mosquitoes, ticks, and rodents. The IPCC AR5 notes that climate
change may influence the ``growth, survival, persistence, transmission,
or virulence of pathogens'' \123\ that cause food and water-borne
disease. The USGCRP NCA3 notes that uncertainty remains regarding
future projections of increased human burden of vector-borne disease,
given complex interacting factors such as ``local, small-scale
differences in weather, human modification of the landscape, the
diversity of animal hosts, and human behavior that affects vector-human
contact, among other factors.'' \124\
---------------------------------------------------------------------------
\123\ IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and
Vulnerability. Part A: Global and Sectoral Aspects. Contribution of
Working Group II to the Fifth Assessment Report of the
Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros,
D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee,
K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N.
Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)].
Cambridge University Press, p. 726.
\124\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 225.
---------------------------------------------------------------------------
Regarding aeroallergens, the assessment literature cited in the
2009 Endangerment Finding found potential for climate change to affect
the prevalence and severity of allergy symptoms, but that definitive
data or conclusions were lacking on how climate change might impact
aeroallergens in the United States. The most recent assessments now
express greater confidence that climate change will influence
production of pollen, which in turn could affect the incidence of
asthma and other allergic respiratory illnesses such as allergic
rhinitis, as well as effects on conjunctivitis and dermatitis. Both the
USGCRP NCA3 and the IPCC AR5 found that increasing temperature has
lengthened the allergenic pollen season for ragweed, and that increased
CO2 by itself can elevate production of plant-based
allergens. The IPCC AR5 concludes that in North America, ``warming will
lead
[[Page 37779]]
to further changes in the seasonal timing of pollen release (high
confidence).'' \125\
---------------------------------------------------------------------------
\125\ IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and
Vulnerability. Part B: Regional Aspects. Contribution of Working
Group II to the Fifth Assessment Report of the Intergovernmental
Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D.
Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O.
Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S.
MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge
University Press, Cambridge, p. 1465-1466.
---------------------------------------------------------------------------
The assessment literature cited in the 2009 Endangerment Finding
concluded that certain populations, including children, the elderly,
and the poor, are most vulnerable to climate-related health effects.
The 2009 Endangerment Finding also described climate change impacts
facing indigenous peoples in the United States, particularly Alaska
Natives. The new assessment literature strengthens these conclusions by
providing more detailed findings regarding these populations'
vulnerabilities and the projected impacts they may experience. In
addition, the most recent assessment reports provide new analysis about
how some populations defined jointly by ethnic/racial characteristics
and geographic location may be vulnerable to certain climate change
health impacts. The following paragraphs summarize information from the
most recent assessment reports on these vulnerable populations.
The USGCRP NCA3 finds that, ``Climate change will, absent other
changes, amplify some of the existing health threats the nation now
faces. Certain people and communities are especially vulnerable,
including children, the elderly, the sick, the poor, and some
communities of color.'' \126\ Limited resources make low-income
populations more vulnerable to ongoing climate-related threats, less
able to adapt to anticipated changes, and less able to recover from
climate change impacts. Low-income populations also face higher
prevalence of chronic health conditions than higher income groups,
which increases their vulnerability to the health effects of climate
change.
---------------------------------------------------------------------------
\126\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 221.
---------------------------------------------------------------------------
According to the USGCRP NCA3 and IPCC AR5, some populations defined
jointly by ethnic/racial characteristics and geographic location are
more vulnerable to certain health effects of climate change due to
factors such as existing health disparities (e.g., higher prevalence of
chronic health conditions), increased exposure to health stresses, and
social factors that affect local resilience and ability to recover from
impacts.
The USGCRP NCA3 also finds that climate change, in addition to
chronic stresses such as extreme poverty, is affecting indigenous
peoples' health in the United States through impacts such as reduced
access to traditional foods, decreased water quality, and increasing
exposure to health and safety hazards. The IPCC AR5 finds that climate
change-induced warming in the Arctic and resultant changes in
environment (e.g., permafrost thaw, effects on traditional food
sources) have significant observed and projected impacts on the health
and well-being of Arctic residents, especially indigenous peoples.
Small, remote, predominantly-indigenous communities are especially
vulnerable given their ``strong dependence on the environment for food,
culture, and way of life; their political and economic marginalization;
existing social, health, and poverty disparities; as well as their
frequent close proximity to exposed locations along ocean, lake, or
river shorelines.'' \127\ In addition, increasing temperatures and loss
of Arctic sea ice increases the risk of drowning for those engaged in
traditional hunting and fishing.
---------------------------------------------------------------------------
\127\ IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and
Vulnerability. Part B: Regional Aspects. Contribution of Working
Group II to the Fifth Assessment Report of the Intergovernmental
Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D.
Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O.
Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S.
MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge
University Press, Cambridge, p. 1581.
---------------------------------------------------------------------------
The USGCRP NCA3 concludes that children will suffer
disproportionately from climate change given the unique physiological
and developmental factors that occur during this lifestage. Impacts on
children are expected from heat waves, air pollution, infectious and
waterborne illnesses, and mental health effects resulting from extreme
weather events. The IPCC AR5 indicates that children are among those
especially susceptible to most allergic diseases, as well as health
effects associated with heat waves, storms, and floods.
Both the USGCRP and IPCC conclude that climate change will increase
health risks facing the elderly. Older people are at much higher risk
of mortality during extreme heat events. Pre-existing health conditions
also make older adults susceptible to cardiac and respiratory impacts
of air pollution and to more severe consequences from infectious and
waterborne diseases. Limited mobility among older adults can also
increase health risks associated with extreme weather and floods.
3. More Recent Evidence That Greenhouse Gases Endanger Public Welfare
The EPA has carefully reviewed the recent scientific conclusions in
the assessments regarding human-induced climate change impacts on
public welfare.\128\ The EPA finds that they are largely consistent
with or strengthen the underlying science supporting the 2009
Endangerment Finding regarding public welfare effects on food
production and agriculture; forestry; water resources; sea level rise
and coastal areas; energy, infrastructure, and settlements; ecosystems
and wildlife; and impacts on the U.S. population from climate change
effects occurring outside of the United States. These key findings are
described briefly here.
Regarding agriculture, the assessment literature cited in the 2009
Endangerment Finding found potential for increased CO2
levels to benefit yields of certain crops in the short-term, but with
considerable uncertainty. The body of evidence pointed towards
increasing risk of net adverse impacts on U.S. food production and
agriculture over time, with the potential for significant disruptions
and crop failure in the future. The most recent assessments now have
greater confidence that climate change will negatively affect U.S.
agriculture over this century. Specifically, the USGCRP NCA3 concludes,
``While some U.S. regions and some types of agricultural production
will be relatively resilient to climate change over the next 25 years
or so, others will increasingly suffer from stresses due to extreme
heat, drought, disease, and heavy downpours. From mid-century on,
climate change is projected to have more negative impacts on crops and
livestock across the country.'' \129\ The IPCC AR5 concludes, ``Overall
yields of major crops in North America are projected to decline
[[Page 37780]]
modestly by mid-century and more steeply by 2100 among studies that do
not consider adaptation (very high confidence).'' \130\ The IPCC AR5
notes that in the absence of extreme events, climate change may benefit
certain regions and crops, but that in North America significant
harvest losses have been observed due to recent extreme weather events.
In addition, the IPCC SREX assessment specifically notes that projected
changes in extreme weather events will increase disaster risk in the
agriculture sector.
---------------------------------------------------------------------------
\128\ The CAA states that ``[a]ll language referring to effects
on welfare includes, but is not limited to, effects on soils, water,
crops, vegetation, man-made materials, animals, wildlife, weather,
visibility, and climate, damage to and deterioration of property,
and hazards to transportation, as well as effects on economic values
and on personal comfort and well-being, whether caused by
transformation, conversion, or combination with other air
pollutants.'' CAA section 302(h). This language is quite broad.
Importantly, it is not an exclusive list due to the use of the term
``includes, but is not limited to, . . . .'' Effects other than
those listed here may also be considered effects on welfare.
\129\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 16.
\130\ IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and
Vulnerability. Part B: Regional Aspects. Contribution of Working
Group II to the Fifth Assessment Report of the Intergovernmental
Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D.
Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O.
Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S.
MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge
University Press, Cambridge, p. 1462.
---------------------------------------------------------------------------
Regarding forestry, the assessment literature cited in the 2009
Endangerment Finding found that near term benefits to forest growth and
productivity in certain parts of the country from elevated
CO2 concentrations and temperature increases to date are
offset by longer term risks from wildfires and the spread of
destructive pests and disease that present serious adverse risks for
forest productivity. The most recent assessments provide further
support for this conclusion. Both the USGCRP NCA3 and the IPCC AR5
conclude that climate change is increasing risks to forest health from
fire, tree disease and insect infestations, and drought. The IPCC AR5
also notes risks to forested ecosystems associated with changes in
temperature, precipitation amount, and CO2 concentrations,
which can affect species and ecological communities, leading to
ecosystem disruption, reorganization, movement or loss. The NRC Arctic
assessment states that climate change is likely to have a large
negative impact on forested ecosystems in the high northern latitudes
due to the effects of permafrost thaw and greater wildfire frequency,
extent, and severity. The NRC Climate Stabilization Targets assessment
found that for an increase in global average temperature of 1 to
2[deg]C above pre-industrial levels, the area burnt by wildfires in
western North America will likely more than double.
Regarding water resources, the assessment literature cited in the
2009 Endangerment Finding concluded that increasing temperatures and
increased variability in precipitation associated with climate change
will impact water quality and quantity through changes in snowpack,
increased risk of floods, drought, and other concerns such as water
pollution. Similarly, the new assessments further support projections
of water resource impacts associated with increased floods and short-
term drought in most U.S. regions. The USGCRP NCA3 also finds that,
``[c]limate change is expected to affect water demand, groundwater
withdrawals, and aquifer recharge, reducing groundwater availability in
some areas.'' \131\ The IPCC AR5 finds that in part of the western
United States, ``water supplies are projected to be further stressed by
climate change, resulting in less water availability and increased
drought conditions.'' \132\ The IPCC AR5 also projects that climate
change will degrade surface water quality, including the Great Lakes,
and will negatively affect drinking water treatment/distribution and
sewage collection systems.
---------------------------------------------------------------------------
\131\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 70.
\132\ IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and
Vulnerability. Part B: Regional Aspects. Contribution of Working
Group II to the Fifth Assessment Report of the Intergovernmental
Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D.
Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O.
Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S.
MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge
University Press, Cambridge, p. 1456-1457.
---------------------------------------------------------------------------
The assessment literature cited in the 2009 Endangerment Finding
found that the most serious potential adverse effects to coastal areas
are the increased risk of storm surge and flooding in coastal areas
from sea level rise and more intense storms. Coastal areas also face
other adverse impacts from sea level rise such as land loss due to
inundation, erosion, wetland submergence, and habitat loss. The most
recent assessments provide further evidence in line with the science
supporting the 2009 Endangerment Finding. The USGCRP NCA3 finds that,
``Sea level rise, combined with coastal storms, has increased the risk
of erosion, storm surge damage, and flooding for coastal communities,
especially along the Gulf Coast, the Atlantic seaboard, and in
Alaska.'' \133\
---------------------------------------------------------------------------
\133\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 9.
---------------------------------------------------------------------------
The IPCC AR5, the USGCRP NCA3, and three of the new NRC assessments
provide estimates of projected global sea level rise. These estimates,
while not always directly comparable as they assume different emissions
scenarios and baselines, are at least 40 percent larger than, and in
some cases more than twice as large as, the projected rise estimated in
the IPCC AR4 assessment, which was referred to in the 2009 Endangerment
Finding.\134\ The NRC Sea Level Rise assessment projects a global sea
level rise of 0.5 to 1.4 meters by 2100, which is sufficient to lead to
a relative rise in sea level even around the northern coasts of
Washington State, where the land is still rebounding from the
disappearance of the great ice sheets. The NRC National Security
Implications assessment suggests that ``the Department of the Navy
should expect roughly 0.4 to 2 meters global average sea-level rise by
2100.'' \135\ The NRC Climate Stabilization Targets assessment states
that an increase of 3[deg]C will lead to a sea level rise of 0.5 to 1
meter by 2100. While these NRC and IPCC assessments continue to
recognize and characterize the uncertainty inherent in accounting for
ice sheet processes, these revised estimates are consistent with the
assessments underlying the 2009 Endangerment Finding.
---------------------------------------------------------------------------
\134\ The 2007 IPCC AR4 assessment cited in 2009 Endangerment
Finding estimated a projected sea level rise of between 0.18 and
0.59 meters by the end of the century, relative to 1990. It should
be noted that in 2007, the IPCC stated that including poorly
understood ice sheet processes could lead to an increase in the
projections.
\135\ NRC, 2011: National Security Implications of Climate
Change for U.S. Naval Forces. The National Academies Press, p. 28.
---------------------------------------------------------------------------
Regarding climate impacts on energy, infrastructure, and
settlements, the 2009 Endangerment Finding cited the assessment
literature's findings that temperature increases will change heating
and cooling demand; that declining water quantity may adversely impact
the availability of cooling water and hydropower in the energy sector;
and that changes in extreme weather events will threaten energy,
transportation, water, and other key societal infrastructure,
particularly on the coast. The most recent assessments provide further
evidence in line with the science supporting the 2009 Endangerment
Finding. For example, the USGCRP NCA3 finds that, ``Coastal
infrastructure, including roads, rail lines, energy infrastructure,
airports, port facilities, and military bases, are increasingly at risk
from sea level rise and damaging storm surges.'' \136\ The NRC Arctic
assessment identifies threats to human infrastructure in the Arctic
from increased flooding, erosion, and shoreline ice pile-up, or ivu,
associated
[[Page 37781]]
with summer sea ice loss and the increasing frequency and severity of
storms.
---------------------------------------------------------------------------
\136\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 9.
---------------------------------------------------------------------------
Regarding ecosystems and wildlife, the assessment literature cited
in the 2009 Endangerment Finding found that climate change will
predominantly adversely impact both terrestrial and marine biodiversity
and the ability of these ecosystems to provide goods and services. The
NRC Arctic assessment states that major marine and terrestrial biomes
will likely shift pole ward, with significant implications for changing
species composition, food web structures, and ecosystem function. The
NRC Climate Stabilization Targets assessment found that coral bleaching
will increase due both to warming and ocean acidification. The NRC
Understanding Earth's Deep Past assessment notes four of the five major
coral reef crises of the past 500 million years were caused by
acidification and warming that followed GHG increases of similar
magnitude to the emissions increases expected over the next hundred
years. Similarly, the NRC Ocean Acidification assessment finds that
``[t]he chemistry of the ocean is changing at an unprecedented rate and
magnitude due to anthropogenic CO2 emissions; the rate of
change exceeds any known to have occurred for at least the past
hundreds of thousands of years.'' \137\ The assessment notes that the
full range of consequences is still unknown, but the risks ``threaten
coral reefs, fisheries, protected species, and other natural resources
of value to society.'' \138\ The IPCC AR5 also projects biodiversity
losses in marine ecosystems, especially in the Arctic and tropics.
---------------------------------------------------------------------------
\137\ NRC, 2010: Ocean Acidification: A National Strategy to
Meet the Challenges of a Changing Ocean. The National Academies
Press, p. 5.
\138\ Ibid.
---------------------------------------------------------------------------
In general, climate change impacts related to public welfare are
expected to be unevenly distributed across different regions of the
United States and have a greater impact on certain populations, such as
indigenous peoples and the poor. The USGCRP NCA3 finds climate change
impacts such as the rapid pace of temperature rise, coastal erosion and
inundation related to sea level rise and storms, ice and snow melt, and
permafrost thaw are affecting indigenous people in the United States.
Particularly in Alaska, critical infrastructure and traditional
livelihoods are threatened by climate change and, ``[i]n parts of
Alaska, Louisiana, the Pacific Islands, and other coastal locations,
climate change impacts (through erosion and inundation) are so severe
that some communities are already relocating from historical homelands
to which their traditions and cultural identities are tied.'' \139\ The
IPCC AR5 notes, ``Climate-related hazards exacerbate other stressors,
often with negative outcomes for livelihoods, especially for people
living in poverty (high confidence). Climate-related hazards affect
poor people's lives directly through impacts on livelihoods, reductions
in crop yields, or destruction of homes and indirectly through, for
example, increased food prices and food insecurity.'' \140\
---------------------------------------------------------------------------
\139\ Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W.
Yohe, Eds., 2014: Climate Change Impacts in the United States: The
Third National Climate Assessment. U.S. Global Change Research
Program, p. 17.
\140\ IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and
Vulnerability. Part A: Global and Sectoral Aspects. Contribution of
Working Group II to the Fifth Assessment Report of the
Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros,
D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee,
K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N.
Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)].
Cambridge University Press, p. 796.
---------------------------------------------------------------------------
In the 2009 Endangerment Finding, the Administrator considered
impacts on the U.S. population from climate change effects occurring
outside of the United States, such as national security concerns that
may arise as a result of climate change impacts in other regions of the
world. The most recent assessments provide further evidence in line
with the science supporting the 2009 Endangerment Finding. The NRC
Climate and Social Stress assessment found that it would be ``prudent
for security analysts to expect climate surprises in the coming decade
. . . and for them to become progressively more serious and more
frequent thereafter.'' \141\ The NRC National Security Implications
assessment recommends preparing for increased needs for humanitarian
aid; responding to the effects of climate change in geopolitical
hotspots, including possible mass migrations; and addressing changing
security needs in the Arctic as sea ice retreats.
---------------------------------------------------------------------------
\141\ NRC, 2013: Climate and Social Stress: Implications for
Security Analysis. The National Academies Press, p. 18.
---------------------------------------------------------------------------
In addition, the NRC Abrupt Impacts report examines the potential
for tipping points, thresholds beyond which major and rapid changes
occur in the Earth's climate system, as well as in natural and human
systems that are impacted by the changing climate. The Abrupt Impacts
report did find less cause for concern than some previous assessments
regarding some abrupt events within the next century such as disruption
of the oceanic Atlantic Meridional Overturning Circulation (AMOC) and
sudden releases of high-latitude methane from hydrates and permafrost.
But, the same report found that the potential for abrupt changes in
ecosystems, weather and climate extremes, and groundwater supplies
critical for agriculture now seem more likely, severe, and imminent.
The assessment found that some abrupt changes were already underway
(e.g., Arctic sea ice retreat and increases in extinction risk due to
the speed of climate change), and cautioned that even abrupt changes
such as the AMOC disruption that are not expected in this century can
have severe impacts if/when they happen.
4. Consideration of Other Climate Forcers
Both in the 2009 Endangerment Finding and in this action, the
Administrator recognizes that there are other substances in addition to
the six well-mixed GHGs that are emitted from human activities and
affect Earth's climate (referred to as climate forcers). These can be
grouped into two categories: (1) other substances with similar physical
properties to the six well-mixed GHGs--these include the ozone-
depleting substances of chlorofluorocarbons, hydrochlorofluorocarbons,
and halons, as well as nitrogen trifluoride and similar recently
identified substances; and (2) short-lived substances--tropospheric
ozone and its precursor gases, water vapor, and aerosol particles and
precursors. For some short-lived substances--namely, water vapor;
NOX; and aerosol particles including black carbon--their
physical properties result in these substances having different, and
often larger, climate effects when emitted at high altitudes. However,
the very properties that lead to differential climate effects depending
on the altitude of emission--properties that are different from those
of the six well-mixed, long-lived GHGs--lead to more uncertainty in the
scientific understanding of these short-lived substances' total effect
on Earth's climate. More detail is provided below.
As described in section III.B of the 2009 Endangerment Finding and
in section IV.A.1 of this preamble, the primary reasons for defining
the air pollution as the aggregate group of the six well-mixed GHGs
include their common physical properties relevant to climate change
(i.e., long-lived, well-mixed, directly emitted), the fact that these
gases are considered the primary drivers of climate change, and the
fact that these gases remain the best
[[Page 37782]]
understood drivers of anthropogenic climate change. The common physical
properties of the six well-mixed GHGs not only support grouping them
together as a class, but also contribute to their higher degree of
scientific understanding related to climate change, relative to short-
lived substances that are not well-mixed, or substances that are formed
indirectly rather than being directly emitted. After considering
additional information in the new assessments regarding the climate-
relevant substances outside the basket of the six well-mixed GHGs, it
is the Administrator's view that the reasons originally stated for not
including these substances in the scope of the GHG air pollution still
apply at this time. For example, nitrogen triflouride and some other
recently discovered substances are not as well studied or understood as
the six well-mixed GHGs. Similarly, for tropospheric ozone--a short-
lived gas in the atmosphere that is not directly emitted (it forms from
emissions of various precursor gases)--the understanding and
quantification of the link between precursor emissions and climate
change is not as strong as for the six well-mixed GHGs.
Regarding the short-lived substances with different climate effects
when emitted at high altitudes, the Aircraft Petition (see section II
of this preamble) mentions the effects of water vapor and
NOX on clouds and atmospheric chemistry. The major peer-
reviewed scientific assessments of the IPCC and NRC provide the current
state of scientific understanding of these effects; the USGCRP
assessments have not dealt specifically with emissions at high
altitude. The EPA considered the following assessment reports to obtain
the best estimates of these substances' net impact on the climate
system, which is generally discussed in terms of radiative forcing: the
IPCC AR5, the IPCC 2007 Fourth Assessment Report (AR4),\142\ the IPCC
Special Report: Aviation and the Global Atmosphere (IPCC 1999),\143\
the NRC's Advancing the Science of Climate Change (NRC 2010),\144\ and
the NRC's Atmospheric Effects of Aviation: A Review of NASA's Subsonic
Assessment Project (NRC 1999).\145\ In addition to high altitude water
vapor and NOX, the literature indicates that aerosol
particles, including black carbon, emitted at high altitudes have more
interactions with clouds and therefore have different effects on the
global energy balance than do particles emitted at the surface.
---------------------------------------------------------------------------
\142\ IPCC, 2007: Climate Change 2007: The Physical Scientific
Basis. Contribution of Working Group I to the Fourth Assessment
Report of the Intergovernmental Panel on Climate Change [Solomon,
S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor
and H.L. Miller (eds.)] Cambridge University Press, 996 pp.
\143\ IPCC, 1999: Aviation and the Global Atmosphere, Special
Report to the Intergovernmental Panel on Climate Change [Penner,
J.E., D.H. Lister, D.J. Griggs, D.J. Dokken, M. McFarland (eds.)]
Cambridge University Press, 373 pp.
\144\ NRC, 2010: Advancing the Science of Climate Change. The
National Academies Press, 528 pp.
\145\ NRC, 1999: Atmospheric Effects of Aviation: A Review of
NASA's Subsonic Assessment Project. The National Academies Press, 54
pp.
---------------------------------------------------------------------------
The state of the science as represented in the assessment
literature highlights significant scientific uncertainties regarding
the total net forcing effect of water vapor, NOX, and
aerosol particles when emitted at high altitudes. Given these
uncertainties, the Agency is not including them in the proposed
definition of air pollution for purposes of the endangerment finding
under section 231 of the CAA. The short-lived nature of these
substances means that, unlike the long-lived GHGs, the climatic impact
of the substance is dependent on a number of factors such as the
location and time of its emission. The magnitude, and often the
direction (positive/warming or negative/cooling), of the globally
averaged climate impact will differ depending on the location of the
emission due to the local atmospheric conditions (e.g., due to
differing concentrations of other compounds with which the emissions
can react, background humidity levels, or the presence or absence of
clouds). In addition, for emissions at any given location, the spatial
and temporal pattern of the climate forcing will be heterogeneous,
again often differing in direction (for example, in the case of
NOX emissions, the near term effect in the hemisphere in
which the emissions occur is usually warming due to increased ozone
concentrations, but the longer term effects, and effects in the other
hemisphere, are often cooling due to increased destruction of methane).
As the climatic effects of these substances when emitted at high
altitudes were not addressed at length in the 2009 Endangerment
Finding, the following subsections briefly summarize the findings of
the major scientific assessments regarding these substances' climatic
effects at altitude and the various sources of uncertainty surrounding
these estimates.
a. Changes in Clouds From High Altitude Emissions of Water Vapor and
Particles
Aviation-induced cloudiness (sometimes called AIC) refers to all
changes in cloudiness associated with aviation operations, which are
primarily due to the effects of high altitude emissions of water vapor
and particles (primarily sulfates and black carbon). Changes in
cloudiness affect the climate by both reflecting solar radiation
(cooling) and trapping outgoing longwave radiation (warming). Unlike
the warming effects associated with the six long-lived, well-mixed
GHGs, the warming effects associated with changes in cloud cover are
more regional and temporal in nature. The three key components of
aviation-induced cloudiness are persistent contrails, contrail-induced
cirrus, and induced cirrus.
Aircraft engine emissions of water vapor at high altitudes during
flight can lead to the formation of condensation trails, or contrails,
under certain conditions such as ice-supersaturated air masses with
specific humidity levels and temperature. The NRC estimates that
persistent contrails increased cloudiness above the United States by
two percent between 1950 and 1988, with similar results reported over
Europe.\146\ As stated above, clouds can have both warming and cooling
effects, and persistent contrails were once considered to have
significant net warming effects. However, more recent estimates suggest
a smaller overall climate forcing effect of persistent contrails. The
IPCC AR5 best estimate for the global mean radiative forcing from
contrails is 0.01 W/m\2\ (medium confidence and with an uncertainty
range of 0.005 to 0.03 W/m\2\).\147\ To put this number into context,
some examples of other IPCC AR5 best estimates for global mean
radiative forcing include: 1.68 W/m\2\ for CO2 (very high
confidence and with an uncertainty range of 1.33 to 2.03 W/m\2\), 0.97
W/m\2\ for methane (high confidence and with an uncertainty range of
0.74 to 1.20 W/m\2\), and 0.17 W/m\2\ for nitrous oxide (very high
confidence and with an uncertainty
[[Page 37783]]
range of .013 to 0.21 W/m\2\).\148\ In addition, the NRC (2010)
assessment suggested that contrails may affect regional diurnal
temperature differences, but this has been called into question by the
recent findings presented in the IPCC AR5, which suggests that aviation
contrails do not have an effect on mean or diurnal range of surface
temperatures (medium confidence).
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\146\ NRC, 1999: Atmospheric Effects of Aviation: A Review of
NASA's Subsonic Assessment Project. The National Academies Press, 54
pp.
\147\ IPCC, 2013: Climate Change 2013: The Physical Science
Basis. Contribution of Working Group I to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change [Stocker,
T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A.
Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge
University Press, 1535 pp.
\148\ IPCC, 2013: Summary for Policymakers. In: Climate Change
2013: The Physical Science Basis. Contribution of Working Group I to
the Fifth Assessment Report of the Intergovernmental Panel on
Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor,
S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley
(eds.)]. Cambridge University Press, 29 pp.
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Persistent contrails also sometimes lose their linear form and
develop into cirrus clouds, an effect referred to as contrail-induced
cirrus. Studies to date have been unable to isolate this climate
forcing effect, but the IPCC AR5 provides a combined contrail and
contrail-induced cirrus best estimate of 0.05 W/m\2\ (low confidence
and with an uncertainty range of 0.02 and 0.15 W/m\2\).\149\
---------------------------------------------------------------------------
\149\ IPCC, 2013: Climate Change 2013: The Physical Science
Basis. Contribution of Working Group I to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change [Stocker,
T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A.
Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)].Cambridge University
Press, 1535 pp.
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Particles emitted or formed in the atmosphere as a result of
aircraft emissions may also act as ice nuclei and modify naturally
forming cirrus clouds, an effect referred to as ``induced cirrus.'' The
two primary aviation-induced particles are sulfates and black carbon,
and their effects on cirrus cloud modification is an area of active
research. There are significant challenges in estimating the climatic
impacts of induced cirrus; for example, the 2007 IPCC AR4 characterizes
our knowledge of the natural freezing modes in cirrus conditions as
``poor,'' and notes that cirrus cloud processes are not well
represented in global models.\150\ Neither IPCC AR4 nor AR5 provided
global or regional estimates related to this forcing.
---------------------------------------------------------------------------
\150\ IPCC, 2007: Climate Change 2007: The Physical Scientific
Basis. Contribution of Working Group I to the Fourth Assessment
Report of the Intergovernmental Panel on Climate Change [Solomon,
S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor
and H.L. Miller (eds.)] Cambridge University Press, 996 pp.
---------------------------------------------------------------------------
Given differences in scientific understanding of the three
components of aviation-induced cloudiness, the more recent assessments
have not provided estimates of the net climate forcing effect of
changes in clouds from high altitude emissions of water vapor and
particles. Going back to the 1999 IPCC assessment, the science is
characterized as ``very uncertain'' with a range for the best estimate
between 0 to 0.040 W/m\2\.\151\
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\151\ IPCC, 1999: Aviation and the Global Atmosphere, Special
Report to the Intergovernmental Panel on Climate Change [Penner,
J.E., D.H. Lister, D.J. Griggs, D.J. Dokken, M. McFarland (eds.)]
Cambridge University Press, 373 pp.
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b. Direct Radiative Forcing Effects of High Altitude Particle Emissions
The 2009 Endangerment Finding noted that much of the uncertainty
range surrounding the estimate of total net forcing due to all human
activities was due to uncertainties about the cooling and warming
effects of aerosols \152\ (though from all sources, not just aircraft).
The Finding noted that the magnitude of aerosol effects can vary
immensely with location and season of emissions, and also discussed
black carbon as a specific type of aerosol particle, noting that
estimates of its total climate forcing effect have a large uncertainty
range.\153\ Here, we discuss the direct radiative forcing effects of
high altitude emissions of the two primary aviation-induced particles,
sulfates and black carbon.
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\152\ 74 FR at 66517, December 15, 2009.
\153\ 74 FR at 66520, December 15, 2009.
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Aircraft emit precursor gases that convert to sulfate particles in
the atmosphere, such as sulfur dioxide. Sulfate particles have direct
effects on the climate by scattering solar radiation, which results in
cooling. The more recent assessments have not quantified this effect
from aviation. Going back to the 1999 IPCC assessment, the direct
effect of sulfate aerosols from aviation for the year 1992 is estimated
at -0.003 W/m\2\ with an uncertainty range between -0.001 and -0.009 W/
m\2\.\154\
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\154\ IPCC, 1999: Aviation and the Global Atmosphere, Special
Report to the Intergovernmental Panel on Climate Change [Penner,
J.E., D.H. Lister, D.J. Griggs, D.J. Dokken, M. McFarland (eds.)]
Cambridge University Press, 373 pp.
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Black carbon emissions from aviation, which are produced by the
incomplete combustion of jet fuel, primarily absorb solar radiation and
heat the surrounding air, resulting in a warming effect. The more
recent assessments have not quantified this effect from aviation. The
1999 IPCC assessment estimates the global mean radiative forcing of
black carbon emissions to be 0.003 W/m\2\ with uncertainty spanning
0.001 to 0.009 W/m\2\.\155\ The IPCC 1999 assessment suggests that
because the contribution of black carbon in the stratosphere (which
actually contribute to cooling of the surface rather than warming) was
not included in its calculations, its estimates of radiative forcing
were likely to be too high.
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\155\ Ibid.
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c. Changes in Atmospheric Chemistry From High Altitude Nitrogen Oxides
Emissions
Emissions of NOX do not themselves have warming or
cooling effects, but affect the climate through catalyzing changes in
the chemical equilibrium of the atmosphere. High altitude emissions of
NOX increase the concentration of ozone, which has a warming
effect in the short term. Elevated NOx concentrations also lead to an
increased rate of destruction of methane, which has a cooling effect in
the long-term. The reduced methane concentrations eventually contribute
to decreases in ozone, which also decreases the long-term net warming
effect. Thus, the net radiative impact of NOX emissions
depends on the balance between the reductions in methane versus the
production of ozone, which in turn depends on the time scale under
consideration. Quantifying these impacts is an area of active study
with large uncertainties. The quantification of the net global effect
of NOX is difficult because the atmospheric chemistry
effects are heavily dependent on highly localized atmospheric
properties and mixing ratios. Because the background atmospheric
concentration of NOX is important for quantifying the impact
of aviation NOX emissions on ozone and methane
concentrations, the location of aircraft emissions would be an
important additional factor. In addition, NOX has different
residence times in the atmosphere depending on the altitude at which it
is emitted. The residence time of NOX in the upper
troposphere, or roughly the cruise altitude for jet aircraft, is on the
order of several days. Going back to the IPCC 1999 assessment, the
globally averaged radiative forcing estimates for aircraft emissions of
NOX in 1992 were 0.023 W/m\2\ for O3-induced
changes (uncertainty range of 0.011 to 0.046 W/m\2\), and -0.014 W/m\2\
for methane-induced changes (uncertainty range of -0.005 to -0.042 W/
m\2\).\156\
---------------------------------------------------------------------------
\156\ IPCC, 1999: Aviation and the Global Atmosphere, Special
Report to the Intergovernmental Panel on Climate Change [Penner,
J.E., D.H. Lister, D.J. Griggs, D.J. Dokken, M. McFarland (eds.)]
Cambridge University Press, 373 pp.
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The IPCC AR5 presents the impact of aviation NOX
emissions using a different metric, global warming potential (GWP),
which is a measure of the warming impact of a pulse of
[[Page 37784]]
emissions of a given substance over 100 years relative to the same mass
of CO2. The AR5 presents a range from -21 to +75 for GWP of
aviation NOX.\157\ The uncertainty in sign indicates
uncertainty whether the net effect is one of warming or cooling. This
report further suggests that at cruise altitude there is strong
regional sensitivity of ozone and methane to NOX,
particularly notable at low latitudes.
---------------------------------------------------------------------------
\157\ IPCC, 2013: Climate Change 2013: The Physical Science
Basis. Contribution of Working Group I to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change [Stocker,
T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A.
Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge
University Press, 1535 pp.
---------------------------------------------------------------------------
The Administrator notes that NOX emissions are already
regulated under the EPA's rules implementing CAA section 231, at 40 CFR
part 87. The prerequisite endangerment and cause or contribute findings
that formed the basis for these standards, however, did not rely upon
any conclusions regarding the climate forcing impacts of
NOX, but rather the role of NOX emissions as a
precursor to ozone formation in areas that did not meet the National
Ambient Air Quality Standard (NAAQS) for ozone.\158\ The continuing
significant uncertainties regarding NOX as a climate forcer
do not undermine the Agency's prior conclusion under CAA section 231
that emissions of NOX from aircraft engines cause or
contribute to air pollution which may reasonably be anticipated to
endanger public health or welfare due to their contribution to ozone
concentrations that exceed the NAAQS.
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\158\ U.S. EPA, ``Control of Air Pollution from Aircraft and
Aircraft Engines, Emission Standards and Test Procedures for
Aircraft.'' Final Rule, 38 FR 19088, July 17, 1973.
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d. Summary
Overall, the state of the science as represented in the assessment
literature highlights significant scientific uncertainties regarding
the total net forcing effect of water vapor, NOX, and
aerosol particles, when emitted at high altitudes. The dependence of
the effects on where the substance is emitted, and the complex temporal
and spatial patterns that result, mean that the current level of
understanding regarding these short-lived substances is much lower than
for the six long-lived, well-mixed GHGs. Given the aforementioned
scientific uncertainties at present, the Agency is not including these
constituents in the proposed definition of air pollution for purposes
of the endangerment finding under section 231 of the CAA.
C. Summary of the Administrator's Proposed Endangerment Finding Under
CAA Section 231
In sum, the Administrator proposes to find, for purposes of CAA
section 231(a)(2)(A), that elevated atmospheric concentrations of the
six well-mixed GHGs constitute air pollution that endangers both the
public health and the public welfare of current and future generations.
In this proposed action under CAA section 231(a)(2)(A), the EPA relies
primarily on the extensive scientific and technical evidence in the
record supporting the 2009 Endangerment Finding, including the major,
peer-reviewed scientific assessments used to address the question of
whether GHGs in the atmosphere endanger public health and welfare, and
on the analytical framework and conclusions upon which the EPA relied
in making that finding. This proposed finding under section 231
accounts for the EPA's careful consideration not only of the scientific
and technical record for the 2009 Endangerment Finding, but also of
new, major scientific assessments issued since closing the
administrative record for the 2009 Endangerment Finding. No recent
information or analyses published since late 2009 suggest that it would
be reasonable for the EPA to now reach a different or contrary
conclusion for purposes of CAA section 231(a)(2)(A) than the Agency
reached for purposes of section 202(a). In proposing this finding for
purposes of section 231, we are not reopening or revisiting our 2009
Endangerment Finding. To the contrary, in light of the recent judicial
decisions upholding those findings, the EPA believes the 2009
Endangerment Finding is firmly established and well settled.\159\
Moreover, there is no need for the EPA to reopen or revisit that
finding for purposes of making an additional finding under section 231
of the CAA. Therefore, public comments addressing this finding for
purposes of section 231(a)(2)(A) should be limited to the section 231
context; the EPA will not consider or respond to comments on this
proposal that seek a reevaluation of our 2009 Endangerment Finding for
purposes of section 202(a).
---------------------------------------------------------------------------
\159\ CRR, 684 F.3d at 117 (D.C. Cir. 2012), reh'g en banc
denied, 2012 U.S. App. LEXIS 25997, 26313, 26315 (D.C. Cir. 2012);
see also Utility Air Reg. Group v. EPA, 134 S. Ct. at 2438 (2014).
---------------------------------------------------------------------------
V. The Proposed Cause or Contribute Finding for Greenhouse Gases Under
CAA Section 231
As noted above, the Administrator has proposed to define the air
pollution for purposes of the endangerment finding under CAA section
231 to be the aggregate of six well-mixed GHGs in the atmosphere. The
second step of the two-part endangerment test for this proposed finding
is for the Administrator to determine whether the emission of any air
pollutant from certain classes of aircraft engines causes or
contributes to this air pollution. This is referred to as the cause or
contribute finding, and is the second proposed finding by the
Administrator in this action.
Section V.A of this proposal describes the Administrator's
reasoning for using the same definition and scope of the GHG air
pollutant that was used in the 2009 Endangerment Finding. Section V.0
puts forth the Administrator's proposed finding that emissions of well-
mixed GHGs from classes of aircraft engines used in covered aircraft
contribute to the air pollution which endangers public health and
welfare.
A. The Air Pollutant
1. Proposed Definition of Air Pollutant
Under section 231, the Administrator is to determine whether
emissions of any air pollutant from any class or classes of aircraft
engines cause or contribute to air pollution which may reasonably be
anticipated to endanger public health or welfare. As with the 2009
Endangerment Finding that the EPA conducted for purposes of CAA section
202(a), when making a cause or contribute finding under section
231(a)(2), the Administrator must first define the air pollutant being
evaluated. The Administrator has reasonably and logically considered
the relationship between the GHG air pollution and air pollutant: while
the air pollution is the concentration (e.g., stock) of the well-mixed
GHGs in the atmosphere, the air pollutant is the same combined grouping
of the well-mixed GHGs, the emissions of which are analyzed for
contribution (e.g., the flow into the stock). See 74 FR at 66537,
(December 15, 2009), (similar discussion with respect to the finding
for section 202). Thus, for purposes of section 231, the Administrator
is proposing to use the same definition of the air pollutant that was
used in the 2009 Endangerment Finding, namely, the aggregate group of
the same six GHGs: CO2, methane, nitrous oxide,
hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. See 74
Federal Register at 66536-66537, (December 15, 2009), (discussing the
definition of the GHG air pollutant with respect to the finding for
section 202). That is, as for the 2009 Endangerment Finding, the
Administrator is proposing to define a
[[Page 37785]]
single air pollutant made up of these six GHGs.
To reiterate what the Agency has previously stated on this subject,
this collective approach for the contribution test is consistent with
the treatment of GHGs by those studying climate change science and
policy, where it is common practice to evaluate GHGs on a collective,
CO2-equivalent basis.\160\ This collective approach to
defining the air pollutant is not unique; grouping of many substances
with common attributes as a single pollutant is common practice under
the CAA, for example with particulate matter and volatile organic
compounds (VOC). As noted in section IV, these substances share common
attributes that support their grouping as the air pollution for
purposes of the endangerment finding. These same common attributes also
support the Administrator grouping the six GHGs for purposes of
defining the air pollutant for the proposed cause or contribute finding
under CAA section 231.
---------------------------------------------------------------------------
\160\ As detailed in the 2009 Endangerment Finding proposal (74
FR 18904 (April 24, 2009) and continuing today, the UNFCCC, the U.S.
and other Parties report their annual emissions of the six GHGs in
CO2-equivalent units. This facilitates comparisons of the
multiple GHGs from different sources and from different countries,
and provides a measure of the collective warming potential of
multiple GHGs. Emissions of different GHGs are compared using GWPs,
which as described in section IV.B of this preamble are measures of
the warming impact of a pulse of emissions of a given substance over
100 years relative to the same mass of CO2. Therefore,
GWP-weighted emissions are measured in teragrams of CO2
equivalent (Tg CO2eq). The EPA's Greenhouse Gas Reporting
Program (http://www.epa.gov/ghgreporting/index.html, (last accessed
May 12, 2015)) also reports GHG emissions on a CO2-
equivalent basis, recognizing the common and collective treatment of
the six GHGs.
---------------------------------------------------------------------------
The Administrator recognizes that in this case, the aircraft
engines covered by this notice emit two of the six gases, but not the
other four gases. Nonetheless, it is entirely appropriate, and in
keeping with the 2009 Endangerment Finding and past EPA practice, for
the Administrator to define the air pollutant in a manner that
recognizes the shared relevant properties of all these six gases, even
though they are not all emitted from the classes of sources before
her.\161\ For example, a source may emit only 20 of the possible 200-
plus chemicals that meet the definition of VOC in the EPA's
regulations, but that source is evaluated based on its emissions of VOC
and not on its emissions of the 20 chemicals by name. The fact that
these six substances within the definition of GHGs share common,
relevant attributes is true regardless of the type of sources being
evaluated for contribution. By proposing to use the definition of the
air pollutant as comprised of the six GHGs with common attributes, the
Administrator is taking account of these shared attributes and how they
are relevant to the air pollution that endangers public health and
welfare.
---------------------------------------------------------------------------
\161\ In the 2009 Endangerment Finding, the Administrator found
that four of the six gases that were included in the definition of
the air pollutant were emitted by section 202 sources. 74 FR 66496,
66537 (December 15, 2009).
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2. How the Definition of Air Pollutant in the Endangerment
Determination Affects Section 231 Standards
Under section 231(a), the Administrator is required to set
``emission standards applicable to the emission of any air pollutant''
from classes of aircraft engines that the Administrator determines
causes or contributes to air pollution that endangers public health or
welfare. If the Administrator makes a final determination under section
231 that the emissions of the GHG air pollutant from certain classes of
aircraft engines contribute to the air pollution that may reasonably be
anticipated to endanger public health and welfare, then she is called
on to set standards applicable to the emissions of this air pollutant.
The term ``standards applicable to the emissions of any air pollutant''
is not defined, and the Administrator has the discretion to interpret
it in a reasonable manner to effectuate the purposes of section 231 to
set standards that either control the emissions of the group of six
well-mixed gases as a whole and/or control emissions of individual
gases, as constituents of the class. For example, it might be
appropriate to set a standard that measures and controls the aggregate
emissions of the group of GHGs, weighted by CO2 equivalent.
Depending on the circumstances, however, it may be appropriate to set
standards for certain individual gases, or some combination of group
and individual standards. These and other similar approaches could
appropriately be considered in setting a standard or standards
applicable to the emissions of the group of GHGs that are defined as
the air pollutant. The Administrator would consider a variety of
factors in determining what approach to take in setting the standard or
standards; for example, she would consider the characteristics of the
aircraft emissions, such as rate and variability, the kind and
availability of control technology, and other matters relevant to
setting standards under section 231.\162\
---------------------------------------------------------------------------
\162\ In setting GHG emissions standards for model years 2012-
2016 light-duty vehicles, the EPA set fleet-wide average
CO2 equivalent standards for cars and trucks based on a
technology assessment analysis which indicated that there was a wide
range of technologies available for manufacturers to use when
upgrading vehicles to reduce CO2 emissions and improve
fuel economy. The final standards were based on CO2
emissions-footprint curves, where each vehicle has a different
CO2 emissions compliance target depending on its
footprint value (related to the size of the vehicle). The EPA also
set standards to cap tailpipe nitrous oxide, methane emissions, and
provided compliance credits to manufacturers who improved air
conditioning systems, such as through reduced refrigerant leakage
(hydrofluorocarbons) and indirect CO2 emissions related
to the increased load on the engine. 75 FR 25324 (May 7, 2010).
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B. Proposed Cause or Contribute Finding
1. The Administrator's Approach in Making This Proposed Finding
As it did for the 2009 Endangerment Finding, and consistent with
prior practice and current science, the EPA uses annual emissions as a
reasonable proxy for contributions to the air pollution, i.e., elevated
atmospheric concentrations of GHGs. Cumulative anthropogenic emissions
are primarily responsible for the observed change in concentrations in
the atmosphere (i.e., the fraction of a country's or an economic
sector's cumulative emissions compared to the world's GHG emissions
over a long time period will be roughly equal to the fraction of the
change in concentrations attributable to that country or economic
sector); likewise, annual emissions are a reasonable proxy for annual
incremental changes in atmospheric concentrations.
There are a number of possible ways of assessing whether air
pollutants cause or contribute to the air pollution which may
reasonably be anticipated to endanger public health and welfare, and no
single approach is required or has been used exclusively in previous
determinations under the CAA. Because the air pollution against which
the contribution is being evaluated is the six well-mixed GHGs, the
logical starting point for any contribution analysis is a comparison of
the emissions of the air pollutant from the section 231 category to the
total U.S. and total global emissions of the six GHGs. The
Administrator recognizes that there are other valid comparisons that
can be considered in evaluating whether emissions of the air pollutant
cause or contribute to the combined concentration of the six GHGs. To
inform the Administrator's assessment, section V.B.2 presents the
following types of simple and straightforward comparisons of U.S.
aircraft GHG emissions:
As a share of current total U.S. GHG emissions;
As a share of current U.S. transportation GHG emissions;
[[Page 37786]]
As a share of current total global GHG emissions; and
As a share of the current global transportation GHG
emissions.
All annual GHG emissions data are reported on a CO2-
equivalent (CO2eq) basis, which as described above is a
commonly accepted metric for comparing different GHGs. This approach is
consistent with how EPA determined contribution for GHGs under section
202 of the CAA in 2009.
2. Overview of Greenhouse Gas Emissions
Atmospheric concentrations of CO2 and other GHGs are now
at essentially unprecedented levels compared to the distant and recent
past.\163\ This is the unambiguous result of human emissions of these
gases. Global emissions of well-mixed GHGs have been increasing, and
are projected to continue increasing for the foreseeable future.
According to IPCC AR5, total global (from all major emitting sources
including forestry and other land use) emissions of GHGs in 2010 were
about 49,000 teragrams \164\ of CO2 equivalent (Tg
CO2eq).\165\ This represents an increase in global GHG
emissions of about 29 percent since 1990 and 23 percent since 2000. In
2010, total U.S. GHG emissions were responsible for about 14 percent of
global GHG emissions (and about 12 percent when factoring in the effect
of carbon sinks from U.S. land use and forestry).
---------------------------------------------------------------------------
\163\ IPCC, 2013: Summary for Policymakers. In: Climate Change
2013: The Physical Science Basis. Contribution of Working Group I to
the Fifth Assessment Report of the Intergovernmental Panel on
Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor,
S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley
(eds.)]. Cambridge University Press, p. 11.
\164\ One teragram (Tg) = 1 million metric tons = 1 megatonne
(Mt). 1 metric ton = 1,000 kg = 1.102 short tons = 2,205 lbs.
\165\ IPCC, 2014: Climate Change 2014: Mitigation of Climate
Change. Contribution of Working Group III to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change [Edenhofer,
O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth,
A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J.
Savolainen, S. Schl[ouml]mer, C. von Stechow, T. Zwickel and J.C.
Minx (eds.)]. Cambridge University Press, 1435 pp.
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Because 2010 is the most recent year for which IPCC emissions data
are available, we provide 2011 estimates from another widely used and
recognized global dataset, the World Resources Institute's (WRI)
Climate Analysis Indicators Tool (CAIT),\166\ for comparison. According
to WRI/CAIT, the total global GHG emissions in 2011 were 43,816 Tg of
CO2eq, representing an increase in global GHG emissions of
about 42 percent since 1990 and 30 percent since 2000 (excluding land
use, land use change and forestry). These estimates are generally
consistent with those of IPCC. In 2011, WRI/CAIT data indicate that
total U.S. GHG emissions were responsible for about 16 percent of
global emissions, which is also generally in line with the percentages
using IPCC's 2010 estimate described above. According to WRI/CAIT,
current U.S. GHG emissions rank only behind China's, which was
responsible for 24 percent of total global GHG emissions.
---------------------------------------------------------------------------
\166\ World Resources Institute (WRI) Climate Analysis
Indicators Tool (CAIT) Data Explorer (Version 2.0). Available at
http://cait.wri.org (last accessed May 12, 2015).
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The Inventory of U.S. Greenhouse Gas Emissions and Sinks Report
\167\ (hereinafter ``U.S. Inventory''), in which 2013 is the most
recent year for which data are available, indicates that total U.S. GHG
emissions increased by 5.7 percent from 1990 to 2013 (or by about 4.7
percent when including the effects of carbon sinks), and emissions
increased from 2012 to 2013 by 1.8 percent. This 2012 to 2013 increase
was attributable to multiple factors including an increase in carbon
intensity of fuels consumed for electricity generation, a small
increase in vehicle miles traveled and vehicle fuel use, and a colder
winter leading to an increase in heating requirements. The U.S.
Inventory also shows that while overall U.S. GHG emissions grew between
1990 and 2013, transportation GHG emissions grew at a significantly
higher rate, 15 percent, more rapidly than any other U.S. sector.
Within the transportation sector, aircraft remain the single largest
source of GHG emissions not yet subject to any GHG regulations.
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\167\ U.S. EPA, 2015: Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2013, 564 pp. Available at http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html#fullreport, (last
accessed May 12, 2015).
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Section V.B.2.a which follows describes U.S. aircraft GHG emissions
within the domestic context, while section V.B.2.b describes these same
GHG emissions in the global context. Section V.B.2.c addresses future
projections of aircraft GHG emissions.
a. U.S. Aircraft GHG Emissions Relative to U.S. GHG Transportation and
Total U.S. GHG Inventory
Relying on data from the U.S. Inventory, we compare U.S. aircraft
GHG emissions to the transportation sector and to total U.S. GHG
emissions as an indication of the role this source plays in the total
domestic contribution to the air pollution that is causing climate
change. In 2013, total U.S. GHG emissions from all sources were 6,774
Tg CO2eq. As stated above, total U.S. GHG emissions have
increased by almost 6 percent between 1990 and 2013, while U.S.
transportation GHG emissions from all categories have grown 15 percent
since 1990. The U.S. transportation sector was the second largest GHG
emitting sector (behind electricity generation), contributing 1,911 Tg
CO2eq or about 30 percent of total U.S. GHG emissions in
2013. This sectoral total and the total U.S. GHG emissions include
emissions from combustion of U.S. international bunker fuels, which are
fuels used for transport activities, from aviation (both commercial and
military) and marine sources.\168\ Consistent with IPCC guidelines for
common and consistent accounting and reporting of GHGs under the
UNFCCC, the ``U.S. international aviation bunker fuels'' category
includes emissions from combustion of fuel purchased in and used by
aircraft departing from the United States, regardless of whether they
are a U.S. flagged carrier. Total U.S. aircraft emissions clearly
contribute to the U.S. transportation sector's emissions, accounting
for 216 Tg CO2eq or 11 percent of such emissions (see Table
V.1.). In 2013, emissions from aircraft (216 Tg CO2eq) were
the third largest transportation source of GHGs within the United
States, behind light-duty vehicles and medium- and heavy-duty trucks
(totaling 1,494 Tg CO2eq).
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\168\ According to IPCC guidelines for common and consistent
accounting and reporting of GHGs under the UNFCCC, the total U.S.
GHG emissions from the U.S. Inventory that is reported to the UNFCCC
excludes international bunker fuel emissions (aviation and marine
international bunker fuel emissions) from the reported total
national GHG emissions. However, the total U.S. GHG emissions in
this proposed cause or contribute finding section of this action do
include international bunker fuel emissions because we want to
capture the full contribution of U.S. emissions, including those
from U.S. aircraft.
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For purposes of making this cause or contribute finding, the EPA is
focused on, and proposes to include, a set of aircraft engine classes
used in types of aircraft as described below, which corresponds to the
scope of the international CO2 emissions standard
contemplated by ICAO.
As mentioned earlier in section II.D, traditionally the EPA (and
FAA) participates at ICAO in the development of international
standards, and then where appropriate, the EPA establishes domestic
aircraft engine emission standards under CAA section 231 of at least
equivalent stringency to ICAO's standards. An international
CO2 emissions standard is anticipated in February 2016, and
provided that the EPA makes a positive endangerment finding and ICAO
adopts an
[[Page 37787]]
international CO2 emissions standard that is both consistent
with CAA section 231 and appropriate for domestic needs, we would
expect to proceed with promulgating a CO2 emissions standard
(or GHG standard) of at least equivalent stringency domestically. As
described later in section VI.D, the thresholds of applicability for
the international CO2 emissions standard are based on gross
weight as follows: For subsonic jet aircraft, a maximum takeoff mass
(MTOM) greater than 5,700 kilograms; and for subsonic propeller driven
(e.g., turboprop) aircraft, a MTOM greater than 8,618 kilograms.\169\
Applying these gross weight thresholds, our proposed cause or
contribute finding applies to GHG emissions from classes of engines
used in covered aircraft. Examples of covered aircraft would include
smaller jet aircraft such as the Cessna Citation CJ2+ and the Embraer
E170, up to the largest commercial jet aircraft--the Airbus A380 and
the Boeing 747. Other examples of covered aircraft would include larger
turboprop aircraft, such as the ATR 72 and the Bombardier Q400. Our
intention is for the scope of the contribution finding to correspond to
the aircraft engine GHG emissions that are from aircraft that match the
applicability thresholds for the international aircraft CO2 standard.
As such we have also identified aircraft that are not covered aircraft
for purposes of our proposed contribution finding. That includes
aircraft that fall below the international applicability thresholds:
Smaller turboprop aircraft, such as the Beechcraft King Air 350i, and
smaller jet aircraft, such as the Cessna Citation M2. In addition, ICAO
(with U.S. participation) has agreed to exclude ``piston-engine
aircraft,'' ``helicopters,'' and ``military aircraft'' \170\ from the
types of aircraft that would be covered by the anticipated ICAO
standards.\171\ These aircraft would not be covered aircraft and
consequently, we are also not including GHG emissions from classes of
engines used in these types of aircraft in our proposed cause or
contribute finding.
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\169\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard, Circular (Cir) 337, AN/192,
Available at http://www.icao.int/publications/ICAOProducts&Services2015catalogue/cat_2015en.pdf (last accessed May
12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
\170\ ICAO regulations only apply to civil aviation (aircraft
and aircraft engines), and consequently, ICAO regulations do not
apply to military aircraft.
\171\ The applicability of the anticipated international
CO2 standard would be limited to subsonic aircraft, and
would not extend to supersonic aircraft. Since space vehicles (or
spacecraft) will be operated at supersonic speeds, space vehicles
would not be covered by the anticipated international CO2
standard.
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Thus, for the purposes of the cause or contribute finding, the EPA
proposes to include GHG emissions from aircraft engines used in covered
aircraft in the scope of this proposed cause or contribute finding.
This is an equivalent scope of applicability as that contemplated by
ICAO. The majority of the GHG emissions from all classes of aircraft
engines would be covered by this scope of applicability. Below we
describe the contribution of these U.S. covered aircraft GHG emissions
to U.S. GHG emissions, and later in section V.B.2.b we discuss the
contribution of these U.S. covered aircraft emissions to global GHG
emissions.
In 2013, GHG emissions from U.S. covered aircraft (which includes
U.S. international aviation bunker fuels in certain cases) comprised 90
percent (195 Tg CO2eq) of total U.S. aircraft GHG emissions
\172\ and 10 percent of total U.S. transportation sector GHG emissions
(See Table V.1.). Overall, U.S. covered aircraft comprised the third
largest source of GHG emissions in the U.S. transportation sector
behind only the light-duty vehicle and medium- and heavy-duty truck
sectors, which is the same ranking as total U.S. aircraft.\173\ The
U.S. covered aircraft also represent 3 percent of total U.S. GHG
emissions, which is approximately equal to the contribution from total
U.S. aircraft of 3.2 percent (Table V.1).\174\
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\172\ Eastern Research Group, Incorporated (ERG), U.S. Jet Fuel
Use and CO2 Emissions Inventory for Aircraft Below ICAO CO2 Standard
Thresholds, Final Report, EPA Contract Number EP-D-11-006, May 7,
2015.
\173\ Compared independently, total U.S. aircraft GHG emissions
and U.S. covered aircraft GHG emissions are both ranked the third
largest source in the U.S. transportations sector, behind only
light-duty vehicle and medium- and heavy-duty truck sectors.
\174\ Total U.S. aircraft GHG emissions and U.S. covered
aircraft GHG emissions were from 12 to 32 percent greater in 2000
and 2005 than in 1990. These increases in aircraft GHG emissions are
primarily because aircraft operations (or number of flights) grew by
similar amounts during this time period. Also, total U.S. aircraft
GHG emissions and U.S. covered aircraft GHG emissions were from 10
to 17 percent greater in 2000 and 2005 than in 2013. These decreases
in aircraft GHG emissions are partly because aircraft operations
decreased by similar amounts during this time period. In addition,
the decreases in aircraft emissions are due in part to improved
operational efficiency that results in more direct flight routing,
improvements in aircraft and engine technologies to reduce fuel burn
and emissions, and the accelerated retirement of older, less fuel
efficient aircraft.
Also, the U.S. transportation GHG emissions were changing at
similar rates as total U.S. aircraft GHG emissions and U.S. covered
aircraft GHG emissions for these same time periods, and thus, the
aircraft GHG emissions share of U.S. Transportation remains
approximately constant (over these time periods).
(U.S. EPA, 2015: Inventory of U.S. Greenhouse Gas Emissions and
Sinks: 1990-2013, 564 pp. Available at http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html#fullreport, Last
accessed May 12, 2015; U.S. FAA. 2015, APO Terminal Area Forecast
Summary Report--Forecast Issued January 2015, http://aspm.faa.gov/apowtaf/.).
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It is important to note that in regard to the six well-mixed GHGs
(CO2, methane, nitrous oxide, hydrofluorocarbons,
perfluorocarbons, and sulfur hexafluoride), only two of these gases--
CO2 and nitrous oxide--are reported as non-zero emissions
for total aircraft and covered aircraft.\175\ CO2 represents
99 percent of all GHGs from both total aircraft (214 Tg
CO2eq) and U.S. covered aircraft (193 Tg CO2eq),
and nitrous oxide represents about one percent from total aircraft (2
Tg CO2eq) and covered aircraft (1.8 Tg CO2eq).
Modern aircraft do not emit methane,\176\ and hydrofluorocarbons,
perfluorocarbons, and sulfur hexafluoride are not products of aircraft
engine combustion.
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\175\ U.S. EPA, 2015: Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2013, 564 pp. Available at http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html#fullreport, (last
accessed May 12, 2015).
\176\ Emissions of methane from jet fuels are no longer
considered to be emitted (based on the latest studies) across the
time series from aircraft gas turbine engines burning jet fuel A at
higher power settings (EPA, Recommended Best Practice for
Quantifying Speciated Organic Gas Emissions from Aircraft Equipped
with Turbofan, Turbojet and Turboprop Engines, EPA-420-R-09-901, May
27, 2009 (see http://www.epa.gov/otaq/regs/nonroad/aviation/420r09901.pdf (last accessed May 12, 2015)). Based on this data,
methane emissions factors for jet aircraft were reported as zero to
reflect the latest emissions testing data. Also, the 2006 IPCC
Guidelines indicate the following: ``Methane (CH4) may be
emitted by gas turbines during idle and by older technology engines,
but recent data suggest that little or no CH4 is emitted
by modern engines.'' (IPCC, 2006: IPCC Guidelines for National
Greenhouse Gas Inventories, The National Greenhouse Gas Inventories
Programme, The Intergovernmental Panel on Climate Change, H.S.
Eggleston, L. Buendia, K. Miwa, T Ngara, and K. Tanabe (eds.).
Hayama, Kanagawa, Japan.) The EPA uses an emissions factor of zero
to maintain consistency with the IPCC reporting guidelines, while
continuing to stay abreast of the evolving research in this area.
For example, one recent study has indicated that modern aircraft jet
engines operating at higher power modes consume rather than emit
methane (Santoni et al., 2011: Aircraft Emissions of Methane and
Nitrous Oxide during the Alternative Aviation Fuel Experiment,
Environ. Sci. Technol., 45, pp. 7075-7082).
[[Page 37788]]
Table V.1--Comparisons of U.S. Aircraft GHG Emissions to Total U.S. Transportation and Total U.S. GHG Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
1990 2000 2005 2010 2011 2012 2013
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total U.S. Aircraft GHG emissions (Tg CO2eq)................. 228 262 254 216 215 212 216
Share of U.S. Transportation................................. 14% 13% 12% 11% 11% 11% 11%
Share of total U.S. Inventory................................ 3.6% 3.6% 3.4% 3.1% 3.1% 3.2% 3.2%
U.S. Covered Aircraft GHG emissions (Tg CO2eq)............... 169 223 217 190 193 190 195
Share of U.S. aircraft GHG emissions......................... 74% 85% 85% 88% 90% 90% 90%
Share of U.S. Transportation................................. 10% 11% 10% 9.7% 10% 9.9% 10%
Share of total U.S. Inventory................................ 2.6% 3% 2.9% 2.7% 2.8% 2.9% 2.9%
Transportation Sector emissions (Tg CO2eq)................... 1,659 2,044 2,137 1,966 1,932 1,907 1,911
Share of total U.S. Inventory................................ 26% 28% 29% 28% 28% 29% 28%
Total U.S. GHG emissions................................. 6,406 7,315 7,464 7,017 6,889 6,652 6,744
--------------------------------------------------------------------------------------------------------------------------------------------------------
b. U.S. Aircraft GHG Emissions Relative to Global Aircraft GHG
Inventory and the Total Global GHG Inventory
For background information and context, we first provide
information on the contribution of GHG emissions from global aircraft
and the global transportation sector to total global GHG emissions, and
describe how this compares to the emissions from aircraft that would be
covered by the anticipated ICAO CO2 standard. We then
compare U.S. aircraft GHG emissions to the global aircraft sector, to
the global transport sector, and to total global GHG emissions as an
indication of the role this source plays in the total global
contribution to the air pollution that is causing climate change. As in
the preceding section, we present comparisons from both total U.S.
aircraft and U.S. covered aircraft.
According to IPCC AR5, global aircraft GHG emissions in 2010 were
11 percent of global transport GHG emissions and 2 percent of total
global GHG emissions. Data from ICAO's 2013 Environmental Report
indicate that the vast majority of global emissions from the aircraft
sector are emitted by the types of aircraft that would be covered by
the anticipated ICAO CO2 standard (``ICAO covered
aircraft'').\177\ When compared to global data from IPCC AR5, worldwide
GHG emissions from ICAO covered aircraft represented about 93 percent
(688 Tg CO2eq) of global aircraft GHG emissions,\178\ 10
percent of global transport GHG emissions, and 1.5 percent of total
global GHG emissions in 2010.
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\177\ ICAO CAEP, 2013: ICAO Environmental Report 2013, Aviation
and Climate Change, 224 pp. Available at http://cfapp.icao.int/Environmental-Report-2013/ (last accessed May 12, 2015).
\178\ Worldwide GHG emissions from ICAO covered aircraft include
emissions from both international and domestic aircraft operations
around the world.
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Comparing data from the U.S. Inventory to IPCC AR5, we find that
total U.S. aircraft GHG emissions represented about 29 percent of
global aircraft GHG emissions, about 3.1 percent of global transport
GHG emissions, and about 0.5 percent of total global GHG emissions in
2010 (see Table V.2). For U.S. covered aircraft in 2010 GHG emissions
represented about 26 percent of global aircraft GHG emissions, 2.7
percent of global transport GHG emissions, and 0.5 percent of total
global GHG emissions (see Table V.2). Because 2010 is the most recent
year for which IPCC emissions data are available, we also made
comparisons using 2011 estimates from WRI/CAIT and the International
Energy Agency (IEA) \179\ and found that they yield very similar
results.\180\
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\179\ International Energy Agency, Data Services. Available at
http://data.iea.org (last accessed May 12, 2015).
\180\ Data from WRI/CAIT and IEA show that, in 2011, total U.S.
aircraft emissions represented about 28 percent of global aircraft
GHG emissions, about 3.7 percent of global transport GHG emissions,
and about 0.5 percent of total global GHG emissions. U.S. covered
aircraft represented about 25 percent of global aircraft GHG
emissions, 3.3 percent of global transport GHG emissions, and 0.5
percent of total global GHG emissions in 2011.
Table V.2--Comparisons of U.S. Aircraft GHG Emissions to Total Global Greenhouse Gas Emissions in 2010
----------------------------------------------------------------------------------------------------------------
Total U.S. U.S. Covered Global
2010 (Tg Aircraft Aircraft Aircraft
CO2 eq) Share (%) Share (%) Share (%)
----------------------------------------------------------------------------------------------------------------
Global Aircraft GHG emissions............................. 743 29 26 ............
Global Transport GHG emissions............................ 7,000 3.1 2.7 11
Total Global GHG emissions................................ 49,000 0.5 0.5 2
----------------------------------------------------------------------------------------------------------------
For additional background information and context, we used 2011
WRI/CAIT and IEA data to make comparisons between the aircraft sector
and the emissions inventories of entire countries and regions. When
compared to entire countries, total global aircraft GHG emissions in
2011 ranked 9th overall, behind only China, United States, India,
Russian Federation, Japan, Brazil, Germany, and Indonesia, and ahead of
about 175 other countries. Total U.S. aircraft GHG emissions have
historically been and continue to be by far the largest contributor to
global aircraft GHG emissions. Total U.S. aircraft GHG emissions are
about 7 times higher than aircraft GHG emissions from China, which
globally is the second ranked country for aircraft GHG emissions, and
about 5 times higher than aircraft GHG emissions from all of Asia. U.S.
covered aircraft GHG emissions are about 6 times more than aircraft GHG
emissions from China, and about 4 times more than aircraft GHG
emissions from all of Asia. If U.S.
[[Page 37789]]
covered aircraft emissions of GHGs were ranked against total GHG
emissions for entire countries, these covered aircraft emissions would
rank ahead of Belgium, Czech Republic, Ireland, Sweden and about 150
other countries in the world.
c. Aircraft GHG Emissions Are Projected To Increase in the Future
While overall GHG emissions from U.S. covered aircraft increased by
about 13 percent from 1990 to 2010, the portion attributable to U.S.
international aviation bunker fuels \181\ increased by about 90
percent.\182\ During this same time period, global aircraft GHG
emissions grew by about 40 percent, and the portion attributable to
global international aviation bunker fuels increased by 80
percent.183 184 Notwithstanding the substantial growth in
GHG emissions from U.S. international aviation bunker fuels, U.S.
covered aircraft emissions have not increased as much as global
aircraft emissions primarily because the U.S. aviation market was
relatively mature compared to the markets in Europe and other emergent
markets, and because during this time period the U.S. commercial air
carriers suffered several major shocks that reduced demand for air
travel.185 186 After consolidation and restructuring in
recent years, the U.S. commercial air carriers have regained
profitability and are forecasted by the FAA to grow more over the next
20 to 30 years.\187\ With regard to global aircraft GHG emissions, the
aviation markets in Asia/Pacific, Europe (where airline deregulation
has stimulated significant new demands in this period), and the Middle
East (and other emerging markets) have been growing rapidly, and the
global market is expected to continue to grow significantly over the
next 20 to 30 years.\188\
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\181\ The U.S. international aviation bunker fuels category
includes emissions from combustion of fuel purchased in and used by
aircraft departing from the United States, regardless of whether
they are a U.S. flagged carrier. GHG emissions from U.S.
international aviation bunker fuels are a subset of GHG emissions
from U.S. covered aircraft. From 1990 to 2010, GHG emissions from
U.S. covered aircraft increased from 169 to 190 Tg CO2eq, and GHG
emissions from the portion attributable to U.S. international
aviation bunker fuels grew from 30 to 58 Tg CO2eq during this same
time period. From 1990 to 2011, GHG emissions from U.S. covered
aircraft increased from 169 to 192 Tg CO2eq (about 14 percent), and
GHG emissions from the portion attributable to U.S. international
aviation bunker fuels grew from 30 to 62 Tg CO2eq (about 110
percent).
\182\ U.S. EPA, 2015: Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2013, 564 pp. Available at http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html#fullreport, (last
accessed May 12, 2015).
\183\ IPCC, 2014: Climate Change 2014: Mitigation of Climate
Change. Contribution of Working Group III to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change [Edenhofer,
O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth,
A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J.
Savolainen, S. Schl[ouml]mer, C. von Stechow, T. Zwickel and J.C.
Minx (eds.)]. Cambridge University Press, pp. 599-670.
\184\ According to IEA, from 1990 to 2011, global aircraft GHG
emissions grew by about 50 percent, and global international
aviation bunker fuels increased by 80 percent. International Energy
Agency Data Services, Available at http://data.iea.org (last
accessed May 12, 2015, 2015).
\185\ FAA, 2014: FAA Aerospace Forecast Fiscal Years 2014-2034,
129 pp. Available at https://www.faa.gov/about/office_org/headquarters_offices/apl/aviation_forecasts/aerospace_forecasts/2014-2034/media/2014_FAA_Aerospace_Forecast.pdf (last accessed May
12, 2015).
\186\ These shocks include the September 11 terror attacks,
significant increases in fuel prices, debt restructuring in Europe
and U.S., and a global recession.
\187\ According to the FAA Aerospace Forecast 2014-2034, in 2013
U.S. air carriers were profitable for the fourth consecutive year.
\188\ According to the FAA Aerospace Forecast 2014-2034, the
International Air Transport Association (IATA) reports that world
air carriers (including U.S. airlines) are expected to register an
operating profit for 2013. Based on financial data compiled by ICAO
and IATA, between 2004 and 2013 world airlines produced cumulative
operating profits (with nine years out of ten posting gains) and net
profits (with six years out of ten posting gains).
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Recent studies estimate that both ICAO covered aircraft and U.S.
covered aircraft will experience substantial growth over the next 20 to
30 years in their absolute fuel burn, and that this will translate into
increased GHG emissions. ICAO estimates that the global fuel burn from
ICAO covered aircraft will increase by about 120 percent from 2010 to
2030 and by about 210 percent from 2010 to 2040 (for a scenario with
moderate technology and operational improvements).\189\ The FAA
projects that the fuel consumption from U.S. air carriers and general
aviation aircraft operating on jet fuel will grow by 49 percent from
2010 to 2035, corresponding to an average annual increase rate in fuel
consumption of 1.6 percent.\190\ These aircraft groups (U.S. air
carriers and general aviation aircraft operating on jet fuel) are of
similar scope to the U.S. covered aircraft whose engine GHG emissions
are the subject of this proposed finding. Using fuel burn growth rates
provided above as a scaling factor for growth in GHG emissions
(globally and nationally), it is estimated that GHG emissions from ICAO
covered aircraft and U.S. covered aircraft would increase at a similar
rate as the fuel burn by 2030, 2035, and 2040.
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\189\ ICAO CAEP, 2013: ICAO Environmental Report 2013, Aviation
and Climate Change, 224 pp. Available at http://cfapp.icao.int/Environmental-Report-2013/ (last accessed May 12, 2015).
\190\ FAA, 2015: FAA Aerospace Forecast Fiscal Years 2015-2035,
134 pp. Available at https://www.faa.gov/about/office_org/headquarters_offices/apl/aviation_forecasts/aerospace_forecasts/2015-2035/media/2015_National_Forecast_Report.pdf (last accessed May
12, 2015).
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3. Proposed Contribution Finding for the Single Air Pollutant Comprised
of the of Six Well-Mixed Greenhouse Gases
Taking into consideration the data summarized in section V.B.2
above, the Administrator proposes to find that GHG emissions from
classes of engines used in U.S. covered aircraft, which are subsonic
jet aircraft with a maximum takeoff mass (MTOM) greater than 5,700
kilograms and subsonic propeller driven (e.g., turboprop) aircraft with
a MTOM greater than 8,618 kilograms, contribute to the air pollution
that endangers public health and welfare. The Administrator is not at
this time proposing a contribution finding for GHG emissions from
engines not used in covered aircraft (i.e., those used in smaller
turboprops, smaller jet aircraft, piston-engine aircraft, helicopters
and military aircraft). We solicit comment on the scope of the proposed
contribution finding, whether a broader contribution finding (e.g.,
including all engines used in aircraft certified by the FAA) would be
appropriate, and the extent to which EPA has discretion to establish
standards pursuant to a contribution finding that do not impose
requirements on every engine or class of engines within the scope of
that finding.
It is the Administrator's judgment that the collective GHG
emissions from the classes of engines used in U.S. covered aircraft
clearly contribute, whether the comparison is domestic (10 percent of
all U.S. transportation GHG emissions, representing 3 percent of total
U.S. emissions) or global (26 percent of total global aircraft GHG
emissions representing 3 percent of total global transportation
emissions and 0.5 percent of all global GHG emissions). The proposed
scope of GHG emissions from engines used in U.S. covered aircraft under
this cause or contribute finding would result in the vast majority (90
percent) of U.S. aircraft GHG emissions being included in this
determination. The Administrator believes that consideration of the
global context is important for the cause or contribute test, but that
the analysis should not solely consider the global context. GHG
emissions from engines used in U.S. covered aircraft will become
globally well-mixed in the atmosphere, and thus will have an effect not
only on the U.S. regional climate but also on the global climate as a
whole, for years and indeed many decades to come. It is the
Administrator's view that the cause or contribute test used here
[[Page 37790]]
under CAA section 231 can follow the same reasoning that was used in
the 2009 GHG cause or contribute finding under CAA section 202; that
is, the Administrator believes a positive cause or contribute finding
for GHG emissions from engines used in U.S. covered aircraft is
justified whether only the domestic context is considered, only the
global context is considered, or both the domestic and global GHG
emissions comparisons are viewed in combination.
As was the case in 2009, no single GHG source category dominates on
the global scale, and many (if not all) individual GHG source
categories could appear small in comparison to the total, when, in
fact, they could be very important contributors in terms of both
absolute emissions or in comparison to other source categories,
globally or within the United States. If the United States and the rest
of the world are to combat the risks associated with global climate
change, contributors must do their part even if their contributions to
the global problem, measured in terms of percentage, are smaller than
typically encountered when tackling solely regional or local
environmental issues.'' \191\ Moreover, as the Supreme Court explained
in Massachusetts v. EPA, agencies commonly take an incremental approach
to resolving large issues, stating that, ``[a]gencies, like
legislatures, do not generally resolve massive problems in one fell
regulatory swoop. . . . They instead whittle away at them over time,
refining their preferred approach as circumstances change and as they
develop a more nuanced understanding of how best to proceed.'' 549 U.S.
497, 524 (2007) (citations omitted). The Administrator continues to
believe that these unique, global aspects of the climate change
problem--including that from a percentage perspective there are no
dominating sources emitting GHGs and few sources that would even be
considered to be close to dominating--tend to support consideration of
contribution to the air pollution at lower percentage levels than EPA
typically encounters when analyzing contribution towards a more
localized air pollution problem. Thus, the Administrator, similar to
the approach taken in the 2009 GHG cause or contribute finding under
CAA section 202, is placing weight on the fact that engines \192\ used
in U.S. covered aircraft contribute 3 percent of total U.S. GHG
emissions for the proposed contribution finding and comprise the single
largest transportation source in the United States that has not yet
been regulated for GHG emissions.
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\191\ 74 FR 66543 (December 15, 2009).
\192\ For a standard promulgated under CAA section 231 to be
``applicable to'' emissions of air pollutants from aircraft engines,
it could take many forms, and include multiple elements in addition
to numeric permissible engine exhaust rate. For example, under CAA
section 231, EPA's rules have long-standing regulations addressing
fuel venting, as well as test procedures. See 40 CFR part 87,
subparts B, G and H. Given both the absence of a statutory directive
on what form a CAA section 231 standard must take (in contrast to,
for example, CAA section 129(a)(4), which requires numerical
emissions limitations for emissions of certain pollutants from solid
waste incinerators), and the U.S. Court of Appeals for the DC
Circuit's 2007 NACAA v. EPA ruling that section 231 confers an
unusually broad degree of discretion in establishing aircraft engine
emission standards, it should be possible to reconcile an ICAO
``aircraft standard'' that effectively limits aircraft engine GHG
emissions with a CAA section 231 aircraft engine emission standard
that achieves the same result, even if the GHG standards take a
different form than the traditional thrust-based NOx aircraft engine
emission standards recently issued by ICAO and the EPA. See 40 CFR
part 87, subpart C.
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4. Additional Considerations
The Administrator is also concerned that reasonable estimates of
GHG emissions from engines used in U.S. covered aircraft are projected
to grow over the next 20 to 30 years. Given the projected growth in
aircraft emissions compared to other sectors, it is reasonable for the
Administrator to consider future emissions projections as adding weight
to her primary reliance on annual emissions. Recent projections reveal
that by 2035 GHG emissions from all aircraft and U.S. covered aircraft
engines are likely to increase by almost 50 percent.\193\ By contrast,
it is estimated that by 2035 the light duty vehicle sector will see a
30 percent reduction in GHG emissions from the 2010 baseline, while the
heavy duty vehicle sector will experience a 33 percent increase in GHG
emissions from the 2010 baseline (this projected increase does not
reflect the impact of GHG reductions anticipated from the Phase 2 heavy
duty GHG standards that have not yet been promulgated). In addition, by
2035 the rail sector is projected to experience a 6 percent reduction
in GHG emissions from 2010 baseline.\194\ Because the projected growth
in aircraft engine GHG emissions from U.S. covered aircraft appears to
be greater in percentage terms than other transportation sources, this
future consideration adds weight to the Administrator's proposed
positive contribution finding.
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\193\ As discussed in Section V.B.2.c fuel burn growth rates for
air carriers and general aviation aircraft operating on jet fuel are
projected to grow by 49 percent from 2010 to 2035 and this provides
a scaling factor for growth in GHG emissions which would increase at
a similar rate as the fuel burn by 2030, 2035, and 2040.
\194\ U.S. Energy Information Administration (EIA), 2015: Annual
Energy Outlook (AEO) 2015 with projections to 2040, DOE/EIA-0383,
154 pp. EIA's reference case (used as the baseline in this
comparison) assumes fuel economy levels for light duty vehicles
required to meet federal light duty GHG standards for years 2012-
2025, and for heavy duty trucks GHG standards for years 2014-2018,
plus improvements in vehicles and engines for all subsectors due to
availability of fuel-saving technologies and fuel price effects. EIA
counts biofuels as zero tailpipe GHG emissions. Because the
comparison in this section focuses on tailpipe emissions, we include
them here, at volumes as forecast in the AEO 2015 reference case.
Available at http://www.eia.gov/forecasts/aeo/ (last accessed May
12, 2015).
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VI. Advance Notice of Proposed Rulemaking: Discussion of Ongoing
International Proceedings To Develop Aircraft CO2 Emissions
Standard and Request for Comment
For more than four years, the EPA and FAA have been engaged with
the ICAO's Committee on Aviation Environmental Protection (ICAO/CAEP)
to establish an international CO2 emissions standard which
the EPA could then consider proposing for adoption under its section
231 authority of the CAA. This section of this document serves as an
ANPR to discuss the key issues of the ongoing international proceedings
prior to February 2016, when ICAO/CAEP is expected to finalize an
international aircraft CO2 standard. An ANPR is intended to
solicit comments and/or information from the public prior to an agency
determining whether to propose a rulemaking. As such, an ANPR does not
propose or impose any regulatory requirements. The EPA may choose to
develop an ANPR for actions (such as the promulgation of standards
pursuant to CAA section 231 to implement an international aircraft
CO2 standard domestically) which are still in the early
stages of development and for which public input may be particularly
helpful. This also helps ensure transparency, while assisting the EPA
in obtaining input from a wide range of stakeholders as we continue
work within CAEP to establish an international CO2 aircraft
standard. The EPA is seeking comments from all interested parties,
including small businesses, on a variety of issues related to setting
an international CO2 standard for aircraft, including
whether such standards should apply to in-production aircraft instead
of new aircraft types only, the appropriate effective dates for the
potential international CO2 standard, as well as the
appropriate stringency levels.
CAEP met an important milestone at its 9th meeting (CAEP/9) in 2013
in reaching an agreement on the
[[Page 37791]]
appropriate metric to be used in assessing fuel efficiency (or
CO2 emissions) \195\ of an engine/aircraft combination. They
also reached agreement on a mature certification requirement \196\ to
evaluate CO2 emissions for new aircraft types and also
agreed on certain aspects of the scope of applicability of the
CO2 emissions standard; however, work on applicability
options for in-production aircraft continues.
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\195\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard, Circular (Cir) 337, AN/192,
Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed May 12, 2015). The ICAO Circular 337
is found on page 85 of the ICAO Products & Services 2015 catalog and
is copyright protected; Order No. CIR337. Section 3.2 of this
Circular states the following: ``An important Phase 1 milestone in
the development of the CO2 Standard was reached on 11
July 2012, when the CAEP Steering Group agreed unanimously on a
CO2 metric system to measure the aeroplane fuel burn
performance and therefore the CO2 emissions produced.''
\196\ ICAO defines a certification requirement as a combination
of metric, procedures, instrumentation and measurement methodology,
and compliance requirements.
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At the CAEP Steering Group meeting in November 2013, there was
agreement on a set of stringency options to be used for the cost-
effectiveness analysis, and at the Steering Group meeting in September
2014 there was a decision on the associated inputs for costs and
technology responses to be utilized in the cost-effectiveness analysis
of these stringency options. This analysis, and work on the
applicability of the standard to in-production aircraft and the
certification requirement are scheduled to be completed prior to the
10th CAEP meeting (CAEP/10) in February 2016. As described in section
II.A, the EPA and the FAA traditionally work within the ICAO/CAEP
standard-setting process to establish international emission standards
and related requirements. Under this approach, international emission
standards have first been adopted by ICAO, and subsequently the EPA has
initiated rulemakings under CAA section 231 to establish domestic
standards that are of at least equal stringency as ICAO's standards.
This approach has been affirmed as reasonable by the U.S. Court of
Appeals for the DC Circuit. Provided the EPA makes a positive
endangerment finding \197\ under CAA section 231 and ICAO adopts an
international aircraft CO2 standard that is consistent with
CAA section 231 and U.S. domestic needs, we would expect to proceed
with a similar approach promulgating a CO2 emissions
standard (or GHG standard) of at least equivalent stringency
domestically.
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\197\ As shorthand in this action, in many places we will use
the term ``endangerment finding'' for both endangerment and cause or
contribute findings.
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A. Purpose of the International Standard
At the CAEP Steering Group meeting in 2011, the U.S provided a
paper recommending that CAEP agree that the purpose of the
international CO2 emissions standard be ``to achieve
CO2 emissions reductions from the aviation sector beyond
expected `business as usual'--i.e., a standard that achieves
CO2 emissions reductions from the aviation sector beyond
what would be achieved in the absence of a standard. This would be
analyzed using ICAO criteria of technical feasibility, environmental
benefit, cost effectiveness, and impacts of interdependencies.'' \198\
The Steering Group accepted the U.S. proposal for the purpose of the
international CO2 standard, and it is expected to be
included in the standard setting process. The metric system, stringency
options, costs, technology responses (inputs to be utilized in the
cost-effectiveness analysis), and applicability ultimately chosen will
all have an effect on whether the international CO2
emissions standard adheres to this stated purpose of the standard. The
U.S. continues to support the adoption of an international
CO2 emissions standard that meets this stated purpose, and
the EPA requests comment on this continued support. The EPA requests
comment on how to achieve the purpose of the standard.
B. Applicability of the International CO2 Emissions Standard
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\198\ CAEP (U.S. Working Paper), ``U.S. Position on the
Development of ICAO'S Aircraft CO2 Standard,'' CAEP-SG/
20112-WP/25, Presented by the United States, U.S. Working Paper for
CAEP Steering Group meeting, Beijing, China, 12 to 16 September
2011.
---------------------------------------------------------------------------
The EPA requests comments on the applicability approaches that CAEP
is considering. Specifically, we request comment on whether the
aircraft CO2 standard should apply to in-production
aircraft, including aircraft with any engineered fuel efficiency
improvements (e.g., different engines, redesigned wings, or engine
performance improvement packages, etc.) or whether the aircraft
CO2 standard should apply only to completely new aircraft
type designs. CAEP is also considering a third, alternative approach,
which would redefine a new aircraft type for CO2 purposes to
include in-production aircraft that have a significant change in
CO2 emissions. We are also requesting comment on this
potential alternative option.
In-production aircraft and new aircraft types are defined as
follows:
--In-production aircraft: Those aircraft types which have already
received a Type Certificate, and for which manufacturers either have
existing undelivered sales orders or would be willing and able to
accept new sales orders.199 200 201
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\199\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015).The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
\200\ As described earlier in section D, in existing U.S.
aviation emissions regulations, in-production means newly-
manufactured or built after the effective date of the regulations--
and already certified to pre-existing standards (if emission
standards were established previously).). This is similar to the
current CAEP definition for in-production aircraft types for
purposes of the CO2 standard.
\201\ According to ICAO Cir 337, a Type Certificate is ``[a]
document issued by a Contracting State to define the design of an
aircraft type and to certify that this design meets the appropriate
airworthiness requirements of that State''.
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--New aircraft types: Aircraft types that have applied for a Type
Certificate \202\ after the effective date of a standard and that have
never been manufactured prior to the effective date of a standard.
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\202\ A Type Certificate is a design approval process whereby
the FAA ensures the manufacturer's designs meet the minimum
requirements for aircraft safety and environmental regulations. This
is typically issued only once for each aircraft, and modified as
needed as an aircraft is modified over the course of its production
life. This Type Certificate (for new aircraft types) would be the
initial or new Type Certificate for this aircraft.
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In addition, for context, out of production aircraft are those
aircraft types which have already received a Type Certificate, but for
which manufacturers either have no existing undelivered sales orders or
would not be willing and able to accept new sales orders. These
aircraft are aircraft types that are no longer in active
production.\203\
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\203\ Out of production aircraft that are still in operational
use would become subject to the international standard only if the
standard applied to ``in-use'' aircraft, which it will not since
CAEP has agreed that the international aircraft CO2
standard should not apply to out of production aircraft types. Note,
the EPA's CAA section 231 aircraft engine standards have applied to
in-use aircraft only in very limited situations, such as the
prohibition against fuel venting at 40 CFR 87.11 and smoke number
standards at 40 CFR 87.31. Note, however, that unlike the EPA's
authority to promulgate emission standards for motor vehicles under
CAA section 202(a) or for nonroad engines and vehicles under section
213(a), section 231 of the CAA does not restrict the EPA's authority
to set standards for only new aircraft.
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As described earlier in section II.E, CAEP's Steering Group meeting
in 2010
[[Page 37792]]
agreed that the scope of applicability for the international aircraft
CO2 standard will be subsonic jets with an applicability
weight threshold of maximum takeoff mass (MTOM) greater than 5,700 kg
(12,566 lb) and turboprop aircraft with a MTOM greater than 8,618 kg
(19,000 lb). CAEP also agreed that the international CO2
standard will apply to new aircraft types, but not apply to out of
production aircraft types, and that applying the standard to in-
production aircraft types should not be ruled out.\204\
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\204\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
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It is important to further describe the difference between new
aircraft types and in-production aircraft. There are three categories
of aircraft under consideration when describing a CO2
standard: New aircraft types submitted for certification (known as
clean sheet designs), those with lesser levels of design change, such
as a new series in an established type and model (considered to be
significant partial redesigns), or an aircraft with incremental
improvements.\205\ New aircraft types or new type designs are
significant investments for manufacturers and are used for new and
significantly different designs (also characterized as complete
redesigns). Significant partial redesigns may be characterized as a new
or later series of an established model that may incorporate newly
designed wings and give purchasers more choices of engines. Incremental
improvements are less extensive changes to an aircraft such as
performance improvement packages that may be added to an aircraft or
engine at some point during the production cycle.
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\205\ New aircraft types fall under the initial or new Type
Certificate, and significant partial redesigns and incremental
improvements fall under an amended Type Certificate. Significant
partial redesigns would be a new or later series of an established
model, and incremental improvements would be a part of the same
series as the established model.
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New aircraft types or new type designs are infrequent. The most
recent new type designs introduced in service, such as the Airbus A380
in 2007, the Boeing 787 in 2011, and the original Boeing 777 in
1995,206 207 208 indicate that it is unlikely a new type
design will seek certification in the next 10 to 15 years.\209\ (New
aircraft types (and similarly for significant partial redesigns)
typically yield large fuel burn reductions--10 percent to 20 percent
over the prior generation they replace, and as one might expect, these
significant fuel burn reductions do not happen frequently. Also,
aircraft development programs are expensive. It is not unusual for new
type designs to take 8-10 years to develop, from preliminary design to
entry into service. 210 211) Significant partial redesigns
do not occur often, but are slightly more frequent than new type
designs. For example, after the current significant partial redesign
wave \212\ has passed (which includes the Boeing 747-8, Boeing 737 Max,
Airbus 320 Neo, and Boeing 777-X), we do not currently have knowledge
of many additional significant partial redesigns anticipated over the
next decade (as the previous wave of significant partial redesigns
included the Boeing 777-200LR in 2004, 777-300ER in 2006, 737NG in
1998, Airbus 319 in 1996, and Airbus 330-200 in
1998).213 214 Incremental improvements will likely be
frequent and occur in the near term. One approach CAEP is considering
would be to limit the applicability of any international CO2
standard to only new type designs (or new aircraft types). Under this
approach the international CO2 standard would not apply to
significant partial redesigned aircraft and incremental improvements.
Under another approach CAEP is considering, CAEP would also apply the
international CO2 standard to in-production aircraft (in
addition to new aircraft types). Significant partial redesigned
aircraft and incremental improvements would be characterized as changes
made to in-production aircraft; thus, these categories of aircraft (or
these changes) would need to meet the international CO2
standard under this approach (or they would need to meet the standard
if it also applied to in-production aircraft).\215\
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\206\ Boeing, 2011: Boeing Unveils First 787 to Enter Service
for Japan Airlines, December 14. Available at http://boeing.mediaroom.com/2011-12-14-Boeing-Unveils-First-787-to-Enter-Service-for-Japan-Airlines (last accessed May 12, 2015).
\207\ The Independent, 2012: BA reveals Airbus A380 superjumbo
flight plans, by Peter Woodman, December 11. Available at http://www.independent.co.uk/travel/news-and-advice/ba-reveals-airbus-a380-superjumbo-flight-plans-8405961.html (last accessed May 12, 2015).
\208\ ICF International, CO2 Analysis of
CO2-Reducing Technologies for Aircraft, Final Report, EPA
Contract Number EP-C-12-011, March 17, 2015.
\209\ Ibid.
\210\ Ibid.
\211\ Analysts estimate a new single aisle would have cost $10-
12 billion to develop. The A380 and 787 are estimated to each have
cost around $20 billion to develop; the A350 is estimated to have
cost $15 billion, excluding engine development. Due to the large
development cost of a totally new aircraft design, manufacturers are
opting to re-wing or just re-engine their aircraft (significant
partial redesigns). Boeing is said to have budgeted $5 billion for
the re-wing of the 777 and Airbus and Boeing have budgeted $1-2
billion each for the re-engine of the A320 and the 737, respectively
(excluding engine development costs). Embraer has publically stated
they will need to spend $1-2 billion to re-wing the EMB-175 and
variants. (ICF International, CO2 Analysis of
CO2-Reducing Technologies for Aircraft, Final Report, EPA
Contract Number EP-C-12-011, March 17, 2015.)
\212\ In general, design waves are prompted by the combination
of market demand for new aircraft performance needs (e.g., more
seats for longer range) and the age of existing aircraft, and design
waves are typically enabled by advances in propulsion technology.
\213\ ICF International, CO2 Analysis of
CO2-Reducing Technologies for Aircraft, Final Report, EPA
Contract Number EP-C-12-011, March 17, 2015.
\214\ Insofar as we are going through a wave of major redesign
and service entry now, prospects for further step-function
improvements will be low in the coming 10-15 years. (ICF
International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.)
\215\ As described earlier, CAEP has not ruled out applying the
international CO2 standard to in-production aircraft
types, which are aircraft types that have already received a Type
Certificate and are produced after the effective date of the
standard. In-production aircraft types would include significant
partial redesigned aircraft and incremental improvements. CAEP is
currently considering and analyzing in-production applicability.
---------------------------------------------------------------------------
Another approach for applicability of the international
CO2 standard that CAEP could adopt (or CAEP is considering)
would be an approach based on criteria addressing significant changes
to aircraft designs, which could be considered an applicability
requirement different than that for new aircraft types only and in-
production aircraft. This alternative approach could redefine a new
aircraft type for CO2 purposes to include in-production
aircraft that have a significant change in CO2 emissions,
thus including in-production aircraft in the applicability of the
CO2 standard. The alternative approach could even cover
significant partial redesigned aircraft, depending upon the definition.
CAEP's current mature certification requirement for the international
CO2 standard \216\ provides further detail on technology
changes to aircraft that would affect the aircraft's CO2
metric value. A changed version of an aircraft could be defined as
follows: An aircraft which incorporates changes in type design that may
adversely affect \217\ its CO2 emissions. This possible
definition could also note the
[[Page 37793]]
following: (1) Where the proposed change in design, configuration,
power or mass is so extensive that a substantially new investigation of
compliance with the applicable airworthiness regulations is required,
the aircraft should be considered to be a new type design rather than a
changed version, and (2) ``adversely'' refers to an increase in
CO2 emissions of more than an amount (or percentage) that
has yet to be determined (this amount or criterion is still being
considered by CAEP). The EPA requests comment on this change-based
criteria approach, including how to identify those changes that would
result in treating in-production aircraft as new types subject to the
standard.
---------------------------------------------------------------------------
\216\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337. See Chapter 1.
\217\ Due to substantial market forces to alleviate any adverse
effects on aircraft fuel burn or CO2 emissions, adverse
changes are rare.
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If CAEP were to limit the scope of applicability to new aircraft
types only (and without the significant change criteria approach
described above), the international CO2 standard would not
apply to later series aircraft with redesigned wings, aircraft that are
available with different engines, or aircraft that undergo incremental
improvements. Following are several examples that illustrate this
situation. The re-engined Boeing 737 Max is an example of a significant
partial redesigned aircraft that is expected to enter into service in
2017.\218\ This aircraft would fall under the original Boeing 737 Type
Certificate that was issued in 1967 (and entered into service in
1968)--or more specifically it would fall under an amended Type
Certificate, and it would not be considered a new aircraft type as
defined by CAEP. The current in-production 737s (Next Generation 737s
or commonly abbreviated as 737 NGs) feature newer engines, have
redesigned wings, and entered service in 1998 under the original 737
Type Certificate that was issued in 1967, and these also were not
considered a new type aircraft when they were introduced in 1998.\219\
Another example of an aircraft that does not qualify as a new type is
the Boeing 747-8 aircraft, that entered into service in 2011, and which
included a new wing, new engines, and a lengthened fuselage but fell
under an amended Type Certificate for the original Boeing 747 that was
certified in 1969 (and entered into service in 1969). An example of
incremental improvements to in-production aircraft, is the Boeing Next
Generation 737 performance improvement package which was implemented
between 2011 and 2013 and the Boeing 767-300 winglets that entered into
service in 2008, both of which improve aircraft fuel efficiency. There
are many other examples that exist for different manufacturers and
aircraft around the world as well, but for conciseness, we are limiting
our discussion to these above examples. These examples illustrate the
typical certification for significant partial redesigns and incremental
improvements by various aircraft certificating or certifying
authorities (or national airworthiness authorities) around the world.
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\218\ Boeing, 737 Max Program ``LEAPS'' into Engine Testing,
Article by Eric Olson, July 11, 2014. Available at http://www.boeing.com/boeing/Features/2014/07/bca_737max_leap_07_11_14.page, (last accessed May 12, 2015).
\219\ The original 737 entered service in 1968. The 737 Classic
entered service in 1984, and it had new high bypass engines, an
updated wing, and other aerodynamic improvements. The 737 NGs
entered service in 1998, and they featured a new wing and updated
engines. Several mid-life upgrades were produced for the 737 NGs,
offering improved range, payload, and efficiency. (ICF
International, CO2 Analysis of CO2-Reducing Technologies for
Aircraft, Final Report, EPA Contract Number EP-C-12-011, March 17,
2015.)
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Using CAEP's current definition of new aircraft types (clean sheet
designs, which are completely new aircraft) we cannot today identify
the first aircraft to which the new standard would apply. As the
examples above illustrate, new aircraft types are infrequent,\220\ and
there are no currently announced new type designs that are expected to
be introduced after the implementation dates being analyzed by CAEP--
2020 and 2023. Furthermore, based on provisions to which CAEP has
already agreed,\221\ new aircraft types subject to the CO2
standard would be aircraft that submit an application for a Type
Certificate after the implementation dates of 2020 and 2023 (dates for
the stringency analysis) which would likely result in entry into
service dates of about 2025 or 2028.\222\ If the international
CO2 standard is applied only to new aircraft types, then
CO2 emissions would not be expected to begin to deviate from
business-as-usual (in comparison to CO2 emissions reductions
that would be achieved in the absence of a standard) before 2025.
Therefore, an international standard developed for only new aircraft
types may not actually apply to any new aircraft for at least a decade.
Even if a few new type aircraft are introduced in this timeframe, it
will take even longer for these aircraft to comprise any significant
portion of the fleet. Therefore, applying an international standard
which applies only to new aircraft types will likely result in no
additional CO2 reductions beyond what would have occurred
absent a CO2 standard, either for the near- and mid-term,
about 5 to 10 years from 2016, or even in the longer-term of 20 years
plus.223 224
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\220\ ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
\221\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May.12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337. Section 1.5 states that that the date to be used in
determining the applicability of the CO2 standard is the
date the application for a Type Certificate was submitted to the
certificating authority having jurisdiction over the manufacturer
responsible for the aircraft design. Section 1.6 specifies that an
application shall be effective for the period specified in the
designation of the airworthiness regulations appropriate to the
aircraft type. An application for a Type Certificate is valid for 5
years.
\222\ These dates assume 5 years from application for the
aircraft Type Certificate to entry into service, which is how long
an application is valid for a Type Certificate.
\223\ Approximate time-scales are considered to be 5 years for
near-term, 10 years for mid-term, and 20 years or more for long-
term.
\224\ ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
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The EPA requests comments on the timeframes described above for
introducing new aircraft types and their subsequent penetration into
the fleet. Are there any aircraft manufacturer announcements that we
missed in regard to new aircraft types that will be introduced or apply
for a Type Certificate after 2020 and 2023 (or new aircraft types that
will be introduced or apply for a Type Certificate five years after
these dates)? \225\ If so, what are these new aircraft types? How many
new types are projected to enter the fleet in this timeframe and what
portion of the fleet will they represent?
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\225\ In November 2014, Boeing indicated that it would replace
the 737 with a new aircraft type in 2030. Earlier this decade,
Boeing was assessing an all new clean sheet 737 replacement, but
eventually they decided to re-engine the 737 (the 737 Max) instead.
(Flight Club, Paul Thompson, Here's The Skinny On What's Next For
Boeing, November 16, 2014. Available at http://flightclub.jalopnik.com/heres-the-skinny-on-whats-next-for-boeing-1656206527 (last accessed May 12, 2015), Also, Wichita Business
Journal, Daniel McCoy, Boeing planning 737 MAX replacement by 2030--
What it could mean for Spirit AeroSystems, November 5, 2014.
Available at http://www.bizjournals.com/wichita/blog/2014/11/boeing-planning-737-max-replacement-by-2030-what.html) (last accessed May
12, 2015). We would consider this as a Boeing projection or
sketching out of plans for a new aircraft type, but it is not a
commitment from Boeing.
---------------------------------------------------------------------------
The alternative approach being considered by CAEP and described
earlier (addressing changes in design of in-production aircraft) may
offer an opportunity to cover more aircraft in an earlier timeframe
(including significant partial redesigns), but it is unclear what
effect this approach would have on
[[Page 37794]]
additional CO2 emissions reductions compared to a standard
for only new aircraft types. The EPA requests comments on the timeframe
for CO2 emissions reductions and the likely share of annual
aircraft production (or share of in-production aircraft built annually)
that would be affected under this alternative approach.
If ICAO applies the aircraft CO2 emission standard to
in-production aircraft, and subsequently (provided the EPA makes a
positive endangerment finding under CAA section 231(a)) the EPA
establishes domestic aircraft engine standards that are equivalent to
the ICAO international aircraft CO2 standard, this means
that all aircraft built (in-production) after the effective date would
need to certify and comply with the standard to remain in production.
This includes (as described earlier) in-production aircraft with
incremental improvements (though we reiterate this would not include
in-use aircraft). As an example of in-production aircraft, the
Gulfstream G650, which is currently in production and expected to
remain so after 2020, would need to certify and comply with the new
CO2 standard. In the next section we discuss in more detail
how applicability to in-production aircraft could work.
C. CAEP Discussion on In-Production Aircraft Applicability
At the request of the CAEP Steering Group meeting in November 2013,
CAEP began work on defining potential options to implement
applicability requirements for in-production aircraft. Subsequently,
based on the options provided to the 2014 Steering Group meeting, CAEP
decided that it should continue to investigate potential in-production
aircraft applicability options, and that these should be presented at
the July 2015 Steering Group meeting, so that a decision can be taken
at the 10th meeting of CAEP (CAEP/10) in February 2016 regarding
whether the international CO2 standard will apply to in-
production aircraft. There are a wide range of options under
consideration, including both mandatory and voluntary options for
reporting and certification processes for in-production aircraft
applicability, but the 2014 Steering Group meeting requested that CAEP
focus on defining the mandatory options (in contrast to options such as
voluntary reporting and certification).
1. Applicability to In-Production Aircraft and Date of Implementation
At the 2014 Steering Group meeting, CAEP also agreed that 2023
represented the earliest possible date for an in-production aircraft
standard to allow time to promulgate domestic regulations and process
manufacturer certification applications. CAEP did not rule out later
dates though and could consider implementation dates for an in-
production aircraft CO2 standard later than 2023 (CAEP could
consider applicability dates for in-production aircraft that are five
years following the new aircraft type applicability date, i.e. dates
ranging from 2023 to 2028).
The EPA seeks comments on both a 2023 implementation date and on
possible later implementation dates for an in-production domestic
CO2 (or GHG) aircraft engine emissions standard that would
be adopted under CAA section 231,\226\ the impact the date of
implementation might have on per-aircraft GHG or CO2
emissions rates \227\ and the ability of a domestic GHG or
CO2 standard to achieve aircraft emission reductions beyond
what would occur in the absence of such a standard.
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\226\ Traditionally, international emission standards have first
been adopted by ICAO, and subsequently the EPA had initiated
rulemakings under CAA section 231 to establish domestic standards
equivalent to ICAO's standards where appropriate. Provided ICAO
adopts an international aircraft CO2 standard that is
consistent with CAA section 231 and it is appropriate for domestic
needs in the United States, we expect to proceed along a similar
approach for the future CAA section 231 aircraft engine
CO2 standard (or aircraft engine GHG standard), provided
the EPA issues final positive endangerment and cause or contribute
findings under CAA section 231.
\227\ For a standard promulgated under CAA section 231 to be
``applicable to'' emissions of air pollutants from aircraft engines,
it could take many forms, and include multiple elements in addition
to numeric permissible engine exhaust rate. For example, under CAA
section 231, EPA's rules have long-standing regulations addressing
fuel venting, as well as test procedures. See 40 CFR part 87,
subparts B, G and H. Given both the absence of a statutory directive
on what form a CAA section 231 standard must take (in contrast to,
for example, CAA section 129(a)(4), which requires numerical
emissions limitations for emissions of certain pollutants from solid
waste incinerators), and the U.S. Court of Appeals for the D.C.
Circuit's 2007 NACAA v. EPA ruling that section 231 confers an
unusually broad degree of discretion in establishing aircraft engine
emission standards, it should be possible to reconcile an ICAO
``aircraft standard'' that effectively limits aircraft engine GHG
emissions with a CAA section 231 aircraft engine emission standard
that achieves the same result, even if the GHG standards take a
different form than the traditional thrust-based NOX
aircraft engine emission standards recently issued by ICAO and the
EPA. See 40 CFR part 87, subpart C.
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As described in section VI.F.2, the technologies considered for the
CAEP analyses are those technologies that will be widely used on in-
production aircraft by 2016 or shortly thereafter.\228\ The EPA
requests comments regarding whether applying an international
CO2 standard to in-production aircraft is consistent with
the purpose of the standard as accepted by the CAEP Steering Group
meeting in 2011: ``to achieve CO2 emission reductions from
the aviation sector beyond expected `business as usual' . . . analyzed
using ICAO criteria of technical feasibility, environmental benefit,
cost effectiveness, and impacts of interdependencies.'' \229\ The
International Coalition for Sustainable Aviation (ICSA),\230\ which is
a CAEP Observer organization, submitted papers to CAEP that analyzed
this issue. Also, a member of ICSA \231\ has developed similar analyses
which indicate that applying the international standard only to new
aircraft types would likely result in no additional CO2
reductions beyond what would have occurred absent a CO2
standard, either for the near- and mid-term, about 5 to 10 years from
2016, or even in the longer-term of 20 years plus. This occurs, the
ICCT states, because the development cycles for new aircraft are very
lengthy and it is not unusual for new aircraft to take 8 to 10 years to
develop from preliminary design to entry into service and once in
service it takes significant time for new aircraft types to penetrate
the fleet.232 233
[[Page 37795]]
Another study funded by the EPA corroborates this analysis.\234\ The
EPA requests comments on whether applying the international
CO2 aircraft standard only to new aircraft types would be
consistent with the accepted purpose of the international standard (the
purpose of the standard that has been accepted by the CAEP Steering
Group). Lastly, the EPA requests comment on the appropriateness of a
possible EPA regulation following either of these approaches
(applicability to only new aircraft types or applicability to both new
types and in-production aircraft) which are under consideration at
CAEP.
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\228\ CAEP determined in 2012 that all technology responses
would have to be based on technology that would be in common use by
the time the standard was to be decided upon in 2016 or shortly
thereafter. This generation of technology was defined within CAEP as
a Technology Readiness Level (TRL) 8--an actual system completed and
``flight qualified'' through test and demonstration--by 2016 or
shortly thereafter.
\229\ CAEP (U.S. Working Paper), ``U.S. Position on the
Development of ICAO'S Aircraft CO2 Standard,'' CAEP-SG/
20112-WP/25, Presented by the United States, U.S. Working Paper for
CAEP Steering Group meeting, Beijing, China, 12 to 16 September
2011. Available at http://www.epa.gov/otaq/aviation.htm. (last
accessed May 12, 2015).
International Coalition for Sustainable Aviation (ICSA),
``ICAO'S CO2 Standard as Part of a Basket of Measures to
Meet Emission Reduction Goals'', ICAO Assembly--38th Session,
Executive Committee, Agenda Item 17--Environmental Protection, A38-
WP/297, EX/99, September 19, 2013.
\230\ The International Coalition for Sustainable Aviation
(ICSA) is a structured network of environmental non-governmental
organizations (NGOs) who share a common concern with civil
aviation's contribution to air quality issues, climate change and
noise, and who are committed to developing and providing technical
expertise, common policy positions and strategies with a view to
reducing emissions and noise from aviation. See http://www.icsa-aviation.org/ (last accessed May 12, 2015).
\231\ The International Council on Clean Transportation (ICCT)
is a member of ICSA, and ICCT is an independent nonprofit
organization founded to provide research and technical and
scientific analysis to environmental regulators. See http://www.theicct.org/ (last accessed May 12, 2015).
\232\ ICCT, Efficiency Trends for New Commercial Jet Aircraft
1960 to 2008, November 2009. Available at http://www.theicct.org/sites/default/files/publications/ICCT_Aircraft_Efficiency_final.pdf
(last accessed May 12, 2015).
\233\ ICCT, ``Could ICAO's CO2 Standard Not Actually
Cover Any Aircraft? Yes, If Nobody's Watching''. Blog, December 9,
2014. Available at http://www.theicct.org/blogs/staff/could-icaos-co2-standard-not-cover-any-aircraft (last accessed May 12, 2015).
\234\ ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
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Also, there have been concerns raised in CAEP about applying the
international CO2 standard to in-production aircraft. These
concerns include (a) the added resource burden on certificating
authorities \235\ to process manufacturers' certification applications,
which will be more numerous compared to new aircraft types; and (b) the
potential added costs to manufacturers to certify in-production
aircraft. The EPA requests comment on these two concerns, including
providing supporting documentation on the extent of these concerns and
any other issues the commenters may identify with applying the
international CO2 standard to in-production aircraft.
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\235\ Pursuant to CAA section 232, the FAA, after consultation
with the EPA, shall prescribe regulations to insure compliance with
all standards prescribed by the EPA under CAA section 231. Section
232 then directs the FAA to include provisions making the EPA's
standards applicable in the issuance, amendment, modification,
suspension, or revocation of any certificate authorized by the FAA
under part A of subtitle VII of Title 49. Under this unique
statutory structure, the EPA promulgates the substantive emission
standards, and the FAA enforces the EPA's standards and insures all
necessary inspections are accomplished.
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2. Reporting Requirement for New In-Production Aircraft
CAEP is working to define mandatory in-production aircraft options,
and one possible option is a reporting requirement
236 237 238 for in-production aircraft CO2
emissions rates (measured according to the aircraft test procedure that
was agreed upon at CAEP/9) as an alternative to establishing an
aircraft CO2 standard for in-production aircraft. Although a
reporting requirement provides policy relevant information, it does not
necessarily translate into specific emissions reductions. The EPA
recognizes that only a mandatory standard for in-production aircraft
would ensure that the aircraft CO2 standard reduces per-
aircraft CO2 emissions rates. However, a reporting
requirement could be an important component of an in-production
aircraft CO2 standard, especially if it is implemented
shortly after an in-production aircraft standard is adopted. It would
ensure that CO2 emissions rates data are gathered quickly
prior to an effective date for the final standard (tracking
CO2 emissions rates is beneficial for the reasons discussed
later in this section and for potentially assisting with the assessment
of a future CO2 standard). The EPA requests comment on an
aircraft manufacturer reporting requirement that is implemented soon
after the adoption of an in-production international aircraft
CO2 standard, as a component of the in-production aircraft
CO2 standard.
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\236\ Currently, CAEP is developing a publicly available
database for aircraft CO2 emissions (CAEP is now
considering format, parameters, etc. for the database), but
submissions to this database by aircraft manufacturers would be
voluntary. There will not be a CAEP mandatory reporting requirement
associated with this potential CO2 database. In addition,
if the international aircraft CO2 standard applies to
only new aircraft types, it could be many years before any data
exists in this database.
\237\ For many years, ICAO has maintained an Aircraft Engine
Emissions Databank for landing and takeoff certificated emissions
values of NOX, hydrocarbon, carbon monoxide, and smoke
number (ICAO and the EPA also have aircraft engine emission
standards for these pollutants). It contains certified emissions
data voluntarily reported from each aircraft engine manufacturer.
This databank is available at https://easa.europa.eu/document-library/icao-aircraft-engine-emissions-databank (last accessed May
12, 2015).
\238\ In 2012, the EPA promulgated annual reporting requirements
for aircraft engine emissions of NOX, hydrocarbon, carbon
monoxide, and smoke number and related parameters. One of the
reasons that the EPA issued these reporting requirements was due to
the varying amount of voluntary data reported by aircraft engine
manufacturers. (U.S. EPA, ``Control of Air Pollution from Aircraft
and Aircraft Engines; Emission Standards and Test Procedures.''
Final Rule, 77 FR 36342 (June 18, 2012)).
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In 2009 the EPA promulgated a final GHG reporting rule that applies
to many sectors in the United States, including manufacturers of heavy-
duty and offroad vehicles and engines, and manufacturers of aircraft
engines.239 240 The EPA's experience with reporting programs
indicates that the EPA and the public would be able to track
CO2 emissions rates trends (i.e., trends of aircraft cruise
fuel burn rates) from aircraft over time. Requiring the reporting of
aircraft CO2 emissions rates trends from aircraft over time
is appropriate and feasible. Requiring aircraft manufacturers to report
aircraft CO2 emissions rates shortly after an in-production
international aircraft standard is adopted would enable and expedite
the tracking and understanding of these emission trends. In addition,
reporting programs typically raise awareness of emissions and can
improve the understanding of the factors that influence emission rates
as well as the actions that can be taken to reduce emissions. When
similar methods for monitoring, measurement, and reporting are applied
across an industry, it can lead to more consistent, accurate, and
timely data to inform decision-making for individual manufacturers and
the EPA (including a comparison of the CO2 emissions rates
from aircraft of various manufacturers). Thus, a reporting requirement
could potentially contribute to efforts to identify and implement
future aircraft CO2 emission reduction opportunities.
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\239\ EPA's 2009 rule on Mandatory Reporting of Greenhouse Gases
included engine manufacturers for the following mobile source
sectors: Highway heavy-duty (engine and vehicle), non-road,
aircraft, locomotive, marine, snowmobiles, and motorcycles.
Manufacturers of aircraft jet engines of rated output (or thrust)
greater than 26.7 kilonewtons are required under this program to
report annually to the EPA CO2 and NOX
emissions from aircraft engines during the landing and takeoff
cycle. Manufacturers of these engines were already measuring and
recording CO2 emissions as part of existing criteria air
pollutant emission requirements for the landing and takeoff cycle,
but prior to this 2009 rule, these data were not reported to the
EPA. Manufacturers voluntarily reported the data to ICAO, but there
was no assurance that the EPA would receive this information, and
thus, the 2009 rule required reporting of the aircraft engine
CO2 and NOX emissions during the landing and
takeoff cycle to the EPA.
\240\ An aircraft manufacturer reporting requirement for in-
production aircraft CO2 emission rates would require the
reporting of aircraft CO2 emissions during the cruise
phase of operation to the EPA. The majority of aircraft
CO2 emissions occurs in the cruise phase of operation,
and thus, reporting CO2 emission rates from this phase
will improve our ability to track full-flight aircraft
CO2 emission rates over time (in addition to reporting
the aircraft engine CO2 emissions during the landing and
takeoff cycle). Also, the aircraft test procedure that was agreed
upon at CAEP/9 now enables us to measure aircraft CO2
emissions during cruise.
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Independent of action that CAEP may or may not take in February
2016, the EPA could under its CAA section 114(a) authority pursue a
reporting requirement for aircraft cruise GHG or CO2
emissions rates--to ensure we have GHG or CO2 emissions
rates data on all in-production aircraft (and any new aircraft types
that enter service).241 The EPA could use the same metric
agreed to at CAEP/9 (and in ICAO circular 337). This will be described
in detail in
[[Page 37796]]
VI.D.1 below. In general, the EPA asks for comment on a mandatory
reporting requirement for in-production aircraft GHG or CO2
emissions rates--either as part of the CAEP international standard or
as an independent domestic requirement to be adopted by the EPA. If the
EPA were to pursue this requirement independently from CAEP, what lead
time would be appropriate for manufacturers to report the GHG or
CO2 emissions rates from all of their in-production aircraft
242 (after we promulgate such a requirement)? Additionally,
if we were to pursue such an independent reporting requirement, should
we require the annual reporting of the GHG or CO2 emissions
rates from in-production aircraft (and any new type aircraft)
243 to enable us to track any updates? We are not at this
time proposing to promulgate such a requirement in advance of ICAO's
decision. Due to the possibility of ICAO's adoption of a reporting
requirement, we believe it is reasonable to await the outcome of that
decision in order to determine whether to strictly follow ICAO's
possible reporting requirement or make changes to it in the form of an
additional U.S. domestic requirement, as appropriate.
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\241\ This GHG or CO2 emissions rate data will help
to track trends, raise awareness, better understand the technology
in the fleet, etc.
\242\ In this case, manufacturers would need to report the GHG
or CO2 emission rates for in-production aircraft
(aircraft types which have already received a Type Certificate, and
for which manufacturers either have existing undelivered sales order
or would be willing and able to accept new sales orders) that are
built after a certain date, which has yet to be determined but would
likely be a date that occurs shortly after we promulgate the
requirement.
\243\ By applying a reporting requirement to in-production
aircraft after a certain implementation date, this reporting
requirement also includes new aircraft types that are produced after
this implementation date.
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D. Metric System, Applicability, and Certification Requirement
The CO2 metric system and mature certification procedure
were agreed upon by CAEP in 2013.244 This section describes
the metric system that was developed, the scope of aircraft to be
covered by the international CO2 standard, the certification
test procedures that would be used to demonstrate compliance with the
international CO2 standard, and CAEP's decision to focus on
the entire aircraft for the international CO2 standard.
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\244\ As described earlier, the certification requirement is the
combination of metric, procedures, instrumentation and measurement
methodology, and compliance requirements. We are using the terms
metric system and certification test procedures to describe these
elements of the certification requirement.
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1. CO2 Metric System
The metric system was developed to cover a wide range of aircraft
types, designs, technology, and uses. To do this, the metric system was
designed to differentiate between generations of aircraft and to
equitably capture improvements in aerospace technology (structural,
propulsion, and aerodynamic) that contribute to a reduction in the
airplane CO2 emissions. In addition, the metric system
accommodates a wide range of technologies and designs which
manufacturers may choose to implement to reduce CO2
emissions from their aircraft.
The metric system agreed to at CAEP uses multiple Specific Air
Range (SAR) test points to represent cruise fuel burn. SAR is a
traditional measure of aircraft cruise performance which measures the
distance an aircraft can travel for a unit of fuel. This is similar to
the instantaneous ``miles per gallon'' readings in many cars today.
However, here the inverse of SAR is used (1/SAR); therefore a lower
metric value represents a better fuel efficiency. The SAR data are
gathered at three gross weight points. The three equally weighted
points are used to represent a range of day to day aircraft
operations.\245\ The functional form of the metric system is provided
below.
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\245\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
[GRAPHIC] [TIFF OMITTED] TP01JY15.000
(1/SAR)avg is calculated at 3 gross weight fractions of
Maximum Takeoff Mass (MTOM):
High gross mass: 92% MTOM
Mid gross mass: Average of high gross mass and low gross mass
Low gross mass: (0.45 * MTOM) + (0.63 * (MTOM-0.924))
The Reference Geometric Factor (RGF) is a measure of the fuselage
size on a given aircraft. In analyzing various metric system options it
was found that in some instances, namely stretch aircraft, changes in
aircraft size, and thus capability, were not reflected in changes to
the aircraft's gross weight (MTOM). To account for these occurrences,
and the variety of methods that manufacturers may use to make such a
change, an adjustment factor was added (the RGF with a 0.24 exponent
used in the metric system).
2. Applicability
CAEP has decided the scope of applicability for a future
international CO2 standard should be subsonic jet and
propeller-driven aircraft meeting the following criteria:
All subsonic jet aircraft over 12,566 lbs (5,700 kg) MTOM.
All subsonic propeller driven (e.g., turboprop) aircraft over
19,000 lbs (8618 kg) MTOM, except amphibious airplanes and those
designed and used for fire-fighting operations.
No military aircraft will be subject to this international
standard.
3. Certification Requirement
CAEP has developed a mature certification requirement \246\ that
would allow for the determination of an aircraft CO2 metric
value for any aircraft meeting the applicability criteria set forth
above. This certification requirement incudes the metric system and
test procedure. The test procedure was based upon industry's current
best practices for establishing the cruise performance of their
aircraft, and input from certification authorities. These procedures
include specifications for aircraft conformity, weighing, fuel
specifications, test condition stability criteria, required confidence
intervals, measurement instrumentation required, and corrections to
reference conditions.
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\246\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
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These CO2 test procedures are based upon manufacturer's
existing practices when certifying new aircraft. This means that there
is a very heavy reliance on dedicated flight testing of the aircraft.
This potentially poses challenges for the certification of in-
production aircraft. Manufacturers have stated that there could be
logistical challenges associated with the certification of aircraft for
CO2 that have previously been type certificated (e.g.
procuring and instrumenting an aircraft for flight testing). To address
this, the EPA is currently working within CAEP to encourage the
development of a modified or separate equivalent certification test
procedure that would reduce this burden on manufacturers
[[Page 37797]]
and allow for quicker/simpler certification of in-production types.
4. Regulating the Entire Aircraft Instead of the Engine
The CO2 metric system intends to equitably reward
improvements in aircraft technologies that reduce emissions, including
advances in structures (aircraft weight), propulsion (engine specific
fuel consumption), and aerodynamics. These three factors are key to the
overall aircraft CO2 emissions. In addition, CAEP has
indicated (and EPA agrees) that it is best to consider the aircraft as
a whole instead of only the aircraft engine technology in addressing
factors that influence CO2 emissions, because of the effects
and interaction these key factors have on the aircraft CO2
emissions from engines.\247\ The three factors--and technology
categories that improve these factors--are described as follows: \248\
Structures: Reducing basic aircraft weight to increase the
commercial payload or extend range for the same amount of thrust and
fuel burn;
Propulsion (thermodynamic and propulsion efficiency): Advancing the
overall specific performance of the engine, to reduce the fuel burn per
unit of delivered thrust; and
Aerodynamics: Advancing the aircraft aerodynamics, to reduce drag
and its associate impacts on thrust.
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\247\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR33.
\248\ ICAO, Environmental Report 2010--Aviation and Climate
Change, 2010, which is located at http://www.icao.int/environmental-protection/Pages/EnvReport10.aspx (last accessed May 12, 2015).
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Specific examples of technologies that affect these three factors
help to further illustrate that it is best to consider the aircraft as
a whole in addressing CO2 emissions. For structural
improvements, aircraft manufacturers have shown significant weight
reduction results over time due to the progressive introduction of new
technologies such as: Advanced alloys and composite materials, improved
and new manufacturing processes and techniques (including integration
and global evaluation simulation), and new systems (e.g. fly-by-
wire).249 250
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\249\ Ibid.
\250\ Fly-by-wire refers to a system which transmits signals
from the cockpit to the aircraft's control surfaces electronically
rather than mechanically. AirlineRatings.com, Available at http://www.airlineratings.com/did-you-know.php?id=18 (last accessed on May
12, 2015, 2015).
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For propulsion improvements, technologies include enhanced
compressors (e.g., intercooled compressors) and reduced hub-tip ratio
fans.\251\ As another example, manufacturers seek higher operating
pressure ratios (OPR) to improve combustion and engine cycle
refinements.
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\251\ ICF International, CO2 Analysis of
CO2-Reducing Technologies for Aircraft, Final Report, EPA
Contract Number EP-C-12-011, March 17, 2015.
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For aerodynamics, friction and lift-dependent drag are the biggest
contributors to aerodynamic drag. Advances in aerodynamics enable
significant lift-dependent drag reduction by maximizing effective wing
span extension. For example, wing-tip devices can give an increase in
the effective aerodynamic span of wings, particularly where wing
lengths are limited by airport gate sizes. Manufacturers are also
looking at ways of decreasing the drag caused by skin friction. An
example of a technology to improve aircraft local skin friction is to
utilize riblets (which are micro-grooves on the surface) to maintain
laminar flow via Natural Laminar Flow and Hybrid Laminar Flow Control
(HLFC) to reduce turbulent skin friction.\252\ The first production
example of a HLFC system went into service on the new Boeing 787-9 in
2014.
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\252\ ICAO, Environmental Report 2010--Aviation and Climate
Change, 2010, which is located at http://www.icao.int/environmental-protection/Pages/EnvReport10.aspx.(last accessed May 12, 2015).
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E. Stringency Options
At the Steering Group meeting in November 2013, CAEP agreed to
analyze a range of CO2 stringency options that cover the
full range of aircraft in-production and in-development around the
world (within the applicable weight thresholds and categories), and
this includes the wide range of technology that is currently in the
aircraft fleet.\253\ Generally, the stringency options that are being
evaluated fall into three categories as follows: (1) CO2
stringency levels that could impact \254\ only the oldest, least
efficient aircraft in-production around the world, (2) middle range
CO2 stringency levels that could impact many aircraft
currently in-production and comprising much of the current operational
fleet, and (3) CO2 stringency levels that could impact
aircraft that have either just entered production or are in final
design phase but will be in-production by the time the international
CO2 standard becomes effective. We are requesting comment on
the level(s) at which the CO2 stringency options should be
set, what factors should be considered in establishing the stringency
of the CO2 standard, and on their potential relationship to
any future CAA section 231 standard.
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\253\ The ICAO standard has the following applicability weight
thresholds: Maximum takeoff mass greater than 5,700 kilograms for
subsonic jet aircraft and maximum takeoff mass greater than 8,618
kilograms for turboprops.
\254\ The aircraft shown in these charts are in-production and
current in-development. These aircraft could be impacted by an in-
production standard in that, if they were above the standard, they
would need to either implement a technology response or go out of
production. For a new type only standard there will be no regulatory
requirement for these aircraft to respond.
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The figures below are intended to show the range of stringency
levels under consideration at CAEP and CO2 metric value
levels of today's in-production and in-development \255\ aircraft. The
data shown were generated by the EPA using a commercially available
aircraft modeling tool called PIANO.\256\ This model contains non-
manufacturer provided estimates of the performance of various aircraft.
In contrast, CAEP is using manufacturer-provided estimates of the
aircraft metric value performance.
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\255\ Aircraft that are currently in-development but will be in
production by the applicability dates. These could be new types or
significant partial redesigned aircraft.
\256\ PIANO (Project Interactive Analysis and Optimization),
Aircraft Design and Analysis Software by Dr. Dimitri Simos, Lissys
Limited, UK, 1990-present; Available at www.piano.aero (last
accessed May 12, 2015). This is a commercially available aircraft
design and performance software suite used across the industry and
academia.
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The stringency options under consideration at CAEP are functions of
the aircraft CO2 Metric Value and have a correlating
parameter of MTOM. They are upwards sloping and have a ``kink'' at
60,000 kilograms MTOM. The ``kink'' was included in the stringency
options as a technical approach to reflect the different behaviors
observed between the larger and smaller aircraft.
The official stringency options under consideration at CAEP have
not been cleared for release outside of the participating members since
deliberations on the standard are still ongoing (proceedings are
expected to be completed at CAEP/10 in February 2016). To show the
relative efficiency of the aircraft, Figure 1 and Figure 2 below show
the aircraft metric values \257\ versus MTOM. In place of the official
stringency options under consideration, lines of constant technology
are used to notionally show how the stringency options were set across
the fleet. These lines reflect the three ranges of options discussed
above. Lower metric values, for a given MTOM, represent an increased
fuel efficiency. Figure 1
[[Page 37798]]
shows the makeup of the current production fleet and the in-development
aircraft. This is what CAEP is using as the starting point for modeling
the effect of the CO2 standard. Figure 2 shows what the EPA
expects the market to look like in 2023, considering the publicly
announced plans by industry to replace existing aircraft with new
products.
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\257\ Metric values were generated using PIANO.
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[[Page 37799]]
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A standard set near the upper-most line of constant technology in
Figures 1 and 2 would affect a very modest number of aircraft, namely
the oldest, least efficient types. Many of the aircraft that would be
affected by such a stringency level are being produced in very limited
numbers and may not be eligible to operate in U.S. air space (e.g.,
Russian and Ukraine aircraft).
Aircraft around the middle two lines of constant technology in
Figures 1 and 2 reflect the performance of many aircraft that are
currently in production and compose much of the current operational
fleet. The current generation of single aisle aircraft from Boeing and
Airbus are in this middle range.
Aircraft near the lowest line of constant technology in Figures 1
and 2 reflect the most advanced aircraft currently for sale on the
market. These are aircraft that have either just entered production or
are still in-development
[[Page 37800]]
but will be in-production by the effective date of a potential in-
production the standard. The replacement single aisle aircraft and new
twin aisle aircraft from Boeing and Airbus are modeled to be clustered
around the lowest line.
While Figures 1 and 2 show the ranges of stringency under
consideration and how aircraft fall within those ranges, because of the
scale, it is hard to see the range of technology present in the fleet.
Therefore Figure 3 and 4 expand the view and show percent differences
between the four constant technology lines represented in Figures 1 and
2. This allows for a clearer view of best and worst performing
aircraft; Figure 3 provides the perspective from the current in-
production and in-development fleet, and Figure 4 projects out to the
2023 fleet. In addition, these figures allow one to compare the
technology level and efficiency of aircraft with differing MTOMs.
[[Page 37801]]
[GRAPHIC] [TIFF OMITTED] TP01JY15.003
[[Page 37802]]
[GRAPHIC] [TIFF OMITTED] TP01JY15.004
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The EPA requests comment on a range of stringency options within
the constant technology lines identified in Figure 1 and Figure 2, on
their potential impact, and on their potential relationship to any
future CAA section 231 standard.
CAEP is considering the possibility of adopting two separate
CO2 stringency levels, one for new type aircraft and one for
in-production aircraft. This would allow stringencies to be set for
both new types and in-production aircraft at a level closer to what
could be achieved by each aircraft type. Issues surrounding the
potential for in-production standards are discussed in section VI.C.1.
[[Page 37803]]
There is ongoing discussion on what appropriate levels of
stringency may be for new type and in-production aircraft. Any final
decisions will have to wait until the full analysis has been conducted
at CAEP. As explained in sections VI.B and VI.C.1, new types are
infrequently developed and typically represent a step change in
technology. It may be possible to set a level of stringency that is
reasonable for in-production aircraft to meet, but at the same time
provide an incentive for new type aircraft to improve. However, this is
challenging to develop because of the significant efficiency
improvements typically seen between in-production and new type
aircraft. The EPA requests comment on the potential for developing a
standard with two stringency levels at CAEP.
The development of a new aircraft type standard must take into
consideration the standard's potential effect on any future type
designs. Even the most stringent option under consideration at CAEP is
still based on technology available today. Any new type aircraft that
may be developed and certified 10 years or more from now would be
expected to use more advanced fuel efficient technology that is not yet
developed or tested.
The implications for an in-production standard are more significant
in the near term for manufacturers. Aircraft currently in-production,
and not meeting the level of an in-production standard, would need to
be modified to meet the standard to remain in production; this would
take time and resources from the manufacturers. The full implications
of this have not yet been resolved in CAEP. However, we expect that the
effect on aircraft CO2 emissions would be minimal for less
stringent options. The aircraft with the highest CO2 metric
values generally rely on older technology and were designed in the
1980's to early 1990's. Many of these aircraft are also expected to be
replaced with updated versions in the near future, before a
CO2 standard would be implemented and go into effect. The
EPA requests comment on the levels at which in-production and new type
standards might be set and on what factors should be considered in
establishing the stringency.
F. Costs, Technology Responses for Stringency Options, and Cost-
Effectiveness Analysis
The EPA has been involved in CAEP's effort to analyze the
CO2 stringency options and the potential costs and
environmental impacts that would result from both new type only
CO2 standards and in-production international CO2
standards. CAEP is still determining the best way to conduct portions
of this analysis. The inputs that have been developed by the CAEP
include non-recurring costs data and technology responses for the
various stringency options under consideration. This section describes
the development of these inputs. The EPA requests comments on how the
modeling should be conducted to differentiate in-production and new
type scenarios.
1. Non-Recurring Costs (engineering development costs)
CAEP developed a single cost estimate that could be used for all
aircraft as a function of MTOM and percent metric value improvement
required. Based on past practice, industry provided estimates for
developing clean sheet designs and significant partial redesigns, only
including high level information that has been made available to the
public. This was considered to be a top down estimate because it
included all aircraft development costs (airworthiness certification,
noise, etc.) not just those for CO2 improvements.
Since the initial dataset provided by industry only included major
changes (or major improvements), the EPA saw the need to supplement
this dataset with an estimate of CO2-only changes (or
CO2-only improvements), which was considered to be a bottom
up estimate. These changes would be much smaller, on the order of a few
percent, and could be applied to in-production aircraft at a cost much
lower than projected by industry. The EPA contracted with ICF
International to develop an estimate of the cost to modify in
production aircraft to comply with a CO2 standard. ICF
International conducted a detailed literature search, conducted a
number of interviews with industry leaders, and did its own modeling to
estimate the cost of making modifications to in production
aircraft.\258\ The results from this peer-reviewed study (small
changes) were then combined with inputs from the industry and the other
CAEP participants (large changes) to develop the CO2
technology response and cost estimation. For the cost estimation, the
CAEP combined the two different methodologies to develop the final cost
surface.\259\
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\258\ ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
\259\ The two datasets were merged together and a single cost
surface was then generated to calculate the cost to modify any
aircraft based on the MTOM, and percent metric value change needed.
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A top-down approach is being used to model large changes to
aircraft design, such as what would be seen in significant partial
redesigns or new types. For significant partial redesigns that result
in new series of an established model, these types of changes may
include: Redesigned wings, new engine options, longer fuselages,
improved aerodynamics, or reduced weight. When making significant
changes to an aircraft many other changes and updates get wrapped into
the process that do not have an effect on the CO2 emissions
of the aircraft, and significant partial redesigns may not have been
spurred by changes to fuel efficiency (CO2 reductions). This
confluence of changes led CAEP to agree that it was reasonable to use
the full development cost for a new type (clean sheet) or significant
partial redesign for major changes. Total costs for past projects were
used to estimate non-recurring cost for the CAEP analysis. This type of
aircraft improvement/development program has historically ranged
approximately from 1 to 15 billion Dollars (U.S.) depending on the size
of the aircraft and scope of the improvements desired.
A bottom-up approach was used, by CAEP, to model smaller
incremental metric value changes to aircraft design. The CAEP agreed
that the above top-down approach would not be the best approach for
minor changes or incremental improvements because the significant
design efforts include many changes that would not be required for
smaller CO2 reductions. The EPA used the information
gathered by ICF International to provide input on the cost for
individual technologies which were used to build up non-recurring costs
for these incremental improvements (a bottom-up approach). The
technologies available to make incremental improvements to aircraft is
wide ranging and aircraft specific. Some examples of technologies that
could be integrated into an aircraft for incremental improvements
include improved fan blade design or reduction in turbine clearances in
the engine, reducing the gap between control surfaces, carbon brake
pads, or advanced wing tip devices. As an example, ICF International
estimated that depending on the additive nature of specific
technologies and the magnitude improvement required, the cost to
incrementally improve the Boeing 767 could range from approximately 230
[[Page 37804]]
million to 1.3 billion US dollars (3.5% to 11% metric value
improvement).\260\
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\260\ ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
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2. Technology Responses
When CAEP started to develop the technology responses for the
stringency options, a determination needed to be made on what level of
technology could be considered as a response to the standard. At the
outset, CAEP decided the international CO2 standard would be
a technology following standard, rather than a technology forcing one.
This means that the international standard would reflect a level of
emissions performance that is already achieved by some portion of
current in-production aircraft.
Additionally, CAEP determined in 2012 that all technology responses
would have to be based on technology that would be in common use by the
time the standard was to be decided upon in 2016 or shortly thereafter.
This generation of technology was defined within CAEP as a Technology
Readiness Level (TRL) 8 \261\--an actual system completed and qualified
through test and demonstration--by 2016 or shortly thereafter. This
means that the technology responses considered for the future
international CO2 standard, going into effect in 2020 or
2023 for new types and potentially in 2023 or later for in-production,
are based on what will be in operation by 2016 or shortly thereafter.
Considering the technology response assumptions agreed to at CAEP, the
EPA requests comment on how the international CO2 standard
should be established so that it meets the purpose of the standard--to
achieve reductions beyond what would have been achieved in the absence
of a standard.
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\261\ TRL is a measure of Technology Readiness Level. CAEP has
defined TRL8 as the ``actual system completed and `flight qualified'
through test and demonstration.'' TRL is a scale from 1 to 9, TRL1
is the conceptual principle, and TRL9 is the ``actual system `flight
proven' on operational flight.'' The TRL scale was originally
developed by NASA. ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, see page 40, March 17, 2015.
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3. Cost Effectiveness Analysis
CAEP is currently conducting the cost effectiveness analysis for
new-type and in-production aircraft. With rare exceptions CAEP has
historically developed new type only standards. To model cost impacts
of a new type standard, CAEP has historically used an assumption that
the in-production aircraft will respond to the new type standard, even
though the standard would not apply to them and has assumed that the
aviation sector is competitive enough that market forces will drive
manufacturers to voluntarily upgrade their fleet to meet any new type
aircraft standard. This scenario is modeled no differently from a
mandatory in-production standard. The EPA requests comment on modeling
cost and environmental impacts of new-type standards based on the
assumed attainment of such emissions levels by in-production aircraft.
Because CAEP has modeled all in-production aircraft as responding
by the implementation date of the new-type standard, CAEP has by
definition, performed an in-production analysis. More stringent options
for new-type aircraft may be restricted due to the assumed in-
production impacts.
CAEP has recognized that its past methods for modeling a new-type
only standard (by assuming in-production aircraft comply) may not be
sufficient for the CO2 standard analysis. Thus, CAEP
developed new methods to model what cost and environmental impacts
would result from only new types being regulated under a new-type
emission standard. CAEP is still determining the best way to conduct an
analysis of impacts only on new types using the agreed upon technology
responses and cost estimates. The EPA requests comments on how to model
cost impacts for only new types for the future international
CO2 standard, if it were to apply only to new types. The EPA
also requests comment on how the modeling should be conducted to
differentiate in-production and new type scenarios.
G. Request for Comment on EPA's Domestic Implementation of
International CO2 Standards
As described earlier in section II.E, traditionally international
emission standards for aircraft engines have first been adopted by
ICAO, and subsequently the EPA has initiated rulemakings to establish
domestic standards that are of at least equal stringency as ICAO's
engine standards. However, the Chicago Convention,\262\ which
established ICAO, recognizes that ICAO member states may adopt their
own unique standards that are more stringent than ICAO standards. A
participating member state (or nation) that adopts more stringent
standards is obligated to notify ICAO of the differences between its
standards and ICAO's standards.\263\
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\262\ ICAO, 2006: Doc 7300-Convention on International Civil
Aviation, Ninth edition, Document 7300/9. Available at: http://www.icao.int/publications/ICAOProducts&Services2015catalogue/cat_2015en.pdf (last accessed May 12, 2015). The ICAO Document 7300
is found on page 1 of the ICAO Products & Services 2015 catalog and
is copyright protected; Order No. 7300.
\263\ According to the Chicago Convention, a participating
member State that adopts regulations or practices differing in any
particular respect from those established by an international
standard is obligated to notify ICAO of the differences between its
standards and ICAO's standards. However, member States that wish to
use aircraft in international transportation must adopt emissions
standards and other recommended practices that are at least as
stringent as ICAO's standards. Member States may ban the use of any
aircraft within their airspace that does not meet ICAO standards.
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Section 231(b) of the CAA requires that any emission standards
``take effect after such period as the Administrator finds necessary
(after consultation with the Secretary of Transportation) to permit the
development and application of the requisite technology, giving
appropriate consideration to the cost of compliance during such
period.'' 42 U.S.C. 7571(b). Section 231(a)(2)(B) provides that the
Administrator shall consult with the Administrator of the FAA on
standards, and ``shall not change the aircraft engine emission
standards if such change would significantly increase noise and
adversely affect safety.'' 42 U.S.C. 7571(a)(2)(B).
As discussed in the 2005 rule (CAEP/4 aircraft engine
NOX standard),\264\ the EPA needs to have a technical basis
for expecting the standards will be achievable in a specific period of
time. While the statutory language of section 231 is not identical to
other provisions in title II of the CAA that direct the EPA to
establish technology-based standards for various types of mobile
sources, the EPA interprets its authority under section 231 to be
similar to those provisions that grant us significant discretion to
identify a reasonable balance of specified emissions reduction, and
cost without adversely affecting safety or increasing noise. See, e.g.,
Husqvarna AB v. EPA, 254 F.3d 195 (D.C. Cir. 2001) (upholding the EPA's
promulgation of technology-based standards for small non-road engines
under section 213(a)(3) of the CAA). In this regard, we note CAEP's
intent for the purpose of the international CO2 standard (as
accepted by the CAEP Steering Group in 2011), which is to achieve
aircraft CO2 emissions reductions beyond that which would
[[Page 37805]]
have occurred in the absence of a standard.
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\264\ U.S. EPA, ``Control of Air Pollution from Aircraft and
Aircraft Engines; Emission Standards and Test Procedures;'' Final
Rule, 70 FR 2521, November 17, 2005.
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In ruling on a petition for judicial review of the 2005 rule,\265\
the U.S. Court of Appeals for the D.C. Circuit held that the EPA's
approach in that action of tracking the ICAO standards was reasonable
and permissible under the CAA. NACAA v. EPA, 489 F.3d 1221, 1230-32
(D.C. Cir. 2007). The Court also held that section 231 of the CAA
confers a broad degree of discretion on the EPA to adopt aircraft
emission standards that the Agency determines are reasonable. Id.
---------------------------------------------------------------------------
\265\ Ibid.
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Although the EPA has traditionally established domestic standards
that track the ICAO standards, for purposes of having a robust ANPR
process, we ask for comment on the possibility of the EPA adopting a
more stringent aircraft engine emissions standard than ICAO, provided
ICAO/CAEP promulgates a standard in 2016 and the EPA makes a positive
endangerment finding. In the same vein, the EPA requests that
commenters consider the following factors (among others): The potential
to reflect the CO2 emissions performance of products from
U.S. manufacturers, competitive advantages and disadvantages for U.S.
manufacturers, certification reciprocity with certificating authorities
of other nations, and the EPA's role in the ongoing ICAO negotiations.
In addition, the EPA asks for comment on what action the EPA should
take if the ICAO/CAEP process fails to result in the adoption of an
aircraft CO2 emissions standard.
VII. Statutory Authority and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is a significant regulatory action because it raises
novel policy issues. Accordingly, it was submitted to the Office of
Management and Budget (OMB) for review. This action proposes a finding
that GHG emissions from aircraft cause or contribute to air pollution
that may be reasonably anticipated to endanger public health and
welfare along with an ANPR which provides an overview of the
international efforts to reduce GHG emissions, progress to date in
establishing global aircraft standards that achieve meaningful
CO2 reductions and, if the EPA finds that aircraft GHG
emissions do cause or contribute to endangerment, the potential use of
CAA section 231 to implement these standards domestically ensuring
transparency and the opportunity for public comment. Any changes made
in response to OMB recommendations have been documented in the docket.
B. Paperwork Reduction Act (PRA)
This action does not impose an information collection burden under
the PRA. The proposed endangerment and cause or contribute findings
under CAA section 231 do not contain any information collection
activities.
C. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities. The proposed
endangerment and cause or contribute findings under CAA section 231 do
not in-and-of-themselves impose any new requirements but rather set
forth the Administrator's proposed determination that GHG emissions
from certain classes of aircraft engines--those used in U.S. covered
aircraft--cause or contribute to air pollution that may be reasonably
anticipated to endanger public health and welfare. Accordingly, this
action affords no opportunity for the EPA to fashion for small entities
less burdensome compliance or reporting requirements or timetables or
exemptions from all or part of the proposal.
D. Unfunded Mandates Reform Act (UMRA)
This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. The action imposes no enforceable duty on any state,
local or tribal governments or the private sector.
E. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.
F. Executive Order 13175: Consultation and Coordination with Indian
Tribal Governments
This action does not have tribal implications as specified in
Executive Order 13175. The proposed endangerment and cause or
contribute findings under CAA section 231 do not in-and-of-themselves
impose any new requirements but rather set forth the Administrator's
proposed determination that GHG emissions from certain classes of
aircraft engines--those used in U.S. covered aircraft--cause or
contribute to air pollution that may be reasonably anticipated to
endanger public health and welfare. Thus, Executive Order 13175 does
not apply to this action.
G. Executive Order 13045: Protection of Children from Environmental
Health Risks and Safety Risks
This action is not subject to Executive Order 13045 because it is
not economically significant as defined in Executive Order 12866. The
Administrator considered climate change risks to children as part of
this proposed endangerment finding under CAA section 231. This action's
discussion of climate change impacts on public health and welfare is
found in section IV of this preamble. Specific discussion with regard
to children are contained in sections IV and I.D of the preamble titled
``Children's Environmental Health.'' A copy of all documents pertaining
to the impacts on children's health from climate change have been
placed in the public docket for this action.
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use
This action is not a ``significant energy action'' because it is
not likely to have a significant adverse effect on the supply,
distribution or use of energy. Further, we have concluded that this
action is not likely to have any adverse energy effects because the
proposed endangerment and cause or contribute findings under section
231 do not in-and-of themselves impose any new requirements but rather
set forth the Administrator's proposed determination that GHG emissions
from certain classes of aircraft engines--those used in U.S. covered
aircraft--cause or contribute to air pollution that may be reasonably
anticipated to endanger public health and welfare.
I. National Technology Transfer and Advancement Act (NTTAA)
This action does not involve technical standards.
J. Executive Order 12898: Federal Actions to Address Environmental
Justice in Minority Populations and Low-Income Populations
The EPA believes this action will not have potential
disproportionately high and adverse human health or environmental
effects on minority, low-
[[Page 37806]]
income, or indigenous populations because this action does not affect
the level of protection provided to human health or the environment.
The Administrator considered climate change risks to minority, low-
income, and indigenous populations as part of this proposed
endangerment finding under CAA section 231. This action's discussion of
climate change impacts on public health and welfare is found in section
IV of the preamble. Specific discussion with regard to minority, low-
income, and indigenous populations are found in sections IV and I.E of
this preamble titled ``Environmental Justice.'' A copy of all documents
pertaining to the impacts on these communities from climate change have
been placed in the public docket for this action.
K. Determination Under Section 307(d)
Section 307(d)(1)(V) of the CAA provides that the provisions of
section 307(d) apply to ``such other actions as the administrator may
determine.'' Pursuant to section 307(d)(1)(V), the Administrator
determines that this action is subject to the provisions of section
307(d).
VIII. Statutory Provisions and Legal Authority
Statutory authority for this action comes from 42 U.S.C. 7571, 7601
and 7607.
List of Subjects
40 CFR Part 87
Environmental protection, Air pollution control, Aircraft, Aircraft
engines.
40 CFR Part 1068
Environmental protection, Administrative practice and procedure,
Confidential business information, Imports, Motor vehicle pollution,
Penalties, Reporting and recordkeeping requirements, Warranties.
Dated: June 10, 2015.
Gina McCarthy,
Administrator.
[FR Doc. 2015-15192 Filed 6-30-15; 8:45 am]
BILLING CODE 6560-50-P