[Senate Hearing 107-1027]
[From the U.S. Government Publishing Office]
S. Hrg. 107-1027
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC) THIRD ASSESSMENT
REPORT
=======================================================================
HEARING
before the
COMMITTEE ON COMMERCE,
SCIENCE, AND TRANSPORTATION
UNITED STATES SENATE
ONE HUNDRED SEVENTH CONGRESS
FIRST SESSION
__________
MAY 1, 2001
__________
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SENATE COMMITTEE ON COMMERCE, SCIENCE, AND TRANSPORTATION
ONE HUNDRED SEVENTH CONGRESS
FIRST SESSION
JOHN McCAIN, Arizona, Chairman
TED STEVENS, Alaska ERNEST F. HOLLINGS, South Carolina
CONRAD BURNS, Montana DANIEL K. INOUYE, Hawaii
TRENT LOTT, Mississippi JOHN D. ROCKEFELLER IV, West
KAY BAILEY HUTCHISON, Texas Virginia
OLYMPIA J. SNOWE, Maine JOHN F. KERRY, Massachusetts
SAM BROWNBACK, Kansas JOHN B. BREAUX, Louisiana
GORDON SMITH, Oregon BYRON L. DORGAN, North Dakota
PETER G. FITZGERALD, Illinois RON WYDEN, Oregon
JOHN ENSIGN, Nevada MAX CLELAND, Georgia
GEORGE ALLEN, Virginia BARBARA BOXER, California
JOHN EDWARDS, North Carolina
JEAN CARNAHAN, Missouri
Mark Buse, Republican Staff Director
Ann Choiniere, Republican General Counsel
Kevin D. Kayes, Democratic Staff Director
Moses Boyd, Democratic Chief Counsel
C O N T E N T S
----------
Page
Hearing held on May 1, 2001...................................... 1
Statement of Senator McCain...................................... 1
Statement of Senator Stevens..................................... 7
Prepared statement of Senator Kerry.............................. 69
Witnesses
Craig, Hon. Larry E., U.S. Senator from Idaho.................... 2
Hagel, Hon. Chuck, U.S. Senator from Nebraska.................... 4
Hansen, Dr. James, Director, Goddard Institute for Space Studies,
National Aeronautics and Space Administration.................. 42
Prepared statement........................................... 44
Lindzen, Dr. Richard S., Massachussetts Institute of Technology.. 24
Prepared statement........................................... 27
McCarthy, James J., Director, Museum of Comparative Zoology,
Harvard University............................................. 19
Prepared statement........................................... 21
Ramaswamy, Dr. Venkatachala, Senior Scientist, Geophysical Fluids
Dynamics Laboratory, National Oceanic and Atmospheric
Administration................................................. 9
Prepared statement........................................... 11
Sathaye, Dr. Jayant A., Senior Scientist, Lawrence Berkeley
National Laboratory, University of California.................. 31
Prepared statement........................................... 33
Appendix
Response by Dr. Venkatachala Ramaswamy to written questions
submitted by Hon. John McCain.................................. 70
Response by Dr. James J. McCarthy to written questions submitted
by Hon. John McCain............................................ 75
Response by Dr. James Hansen to written questions submitted by
Hon. John McCain............................................... 77
Response by Dr. Richard S. Lindzen to written questions submitted
by:
Hon. John McCain............................................. 84
Hon. John Kerry.............................................. 85
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC) THIRD ASSESSMENT
REPORT
----------
TUESDAY, MAY 1, 2001
U.S. Senate,
Committee on Commerce, Science, and Transportation,
Washington, DC.
The Committee met, pursuant to notice, at 9:30 a.m. in room
SR-253, Russell Senate Office Building, Hon. John McCain,
Chairman of the Committee, presiding.
OPENING STATEMENT OF HON. JOHN McCAIN, U.S. SENATOR FROM
ARIZONA
The Chairman. Good morning. Last year, we held three
hearings on the issue of climate change. Today we hope to
continue the dialog on this very important matter confronting
not only the nation but the world. In recent discussions
surrounding the President's position on the Kyoto Protocol
there were several questions concerning the availability of
sound science in the decisionmaking process.
At this hearing, we hope to have an open and frank
discussion on the recent third assessment report by the
Intergovernmental Panel on Climate Change. The IPCC efforts are
recognized as one of the most comprehensive in this matter. It
involves the work of hundreds of scientists from around the
world.
The third assessment report is an up-to-date assessment of
published and peer-reviewed policy relevant scientific,
technical, and socioeconomic literature. The previous
assessment report was issued 5 years ago. The latest report
concludes that a firmer association between human activities
and climate seems to have emerged. I look forward to discussing
the basis for such a conclusion by the panel.
I am disappointed, but not surprised to hear that the most
vulnerable to these changing conditions are those with the
least resources. The report states the effects of climate
change are expected to be the greatest in developing countries
in terms of loss of life and effects on investment and the
economy. Therefore, the developed countries like the United
States must do its share in addressing this global problem.
Any agreement on the Kyoto Protocol will have real effects
on our economy. It is interesting to note that the report
indicates that about half of the emissions reductions targets
may be achieved with a net economic benefit, according to the
report. This sounds like the basis for action to me.
While we appreciate the work of the hundreds of scientists
involved in this effort, we recognize that a substantial amount
of research remains before we can fully understand the complex
and dynamic relationship between the atmosphere, the oceans,
land, and mankind. I plan to review the U.S. research
contributions to this global problem to ensure that our
contributions are helpful and adequate.
I note that much of the assessment report is based upon
computer models, and I must say that I am alarmed to hear about
the recent National Research Council's report on the
shortcomings of the U.S. climate modeling program. We hope that
today's discussion will go a long way in aiding this Committee
and the Congress in crafting future actions to address this
issue. This is the fourth hearing we have held on this topic in
the past year.
I plan to work with the other members of this Committee and
the Senate, along with our witnesses today, to determine the
appropriate next step in this complicated process of addressing
the changing global climate. I welcome all of our witnesses
here today. We would like to start with our two colleagues from
the Senate, Senator Craig and Senator Hagel, and obviously we
would appreciate your remarks and hope that they can be
relatively brief.
Senator Craig, welcome.
STATEMENT OF HON. LARRY E. CRAIG, U.S. SENATOR
FROM IDAHO
Senator Craig. Well, Mr. Chairman, certainly I thank you
for convening this hearing today, and I think you and I both
agree that the potential of climate change is a serious issue
with high stakes. I do believe that premature government action
to cut back energy use to levels lower than those in the
growth-oriented nineties could cool the economy faster than it
cools the climate.
On the other hand, you and I agree that ignoring the
concerns expressed by some respected scientists about recent
warming trends is equally irresponsible. During the last 4
years, Mr. Chairman, you have held hearings, I have held
hearings, Senator Hagel, I, and a good many others have been
involved in the fascinating issue.
I have traveled to Woods Hole to listen to the scientists.
I have traveled to the Hague to see the international politics
of this. I have attended numerous hearings. I have listened and
read the testimony out of the hearings that you have assembled.
Clearly, the scientific community has made impressive gains in
its understanding of global climate change, but with increased
understanding has come increased uncertainty about the relative
roles of greenhouse gases, aerosols, land coverage changes,
ocean currents, in the last century's temperature changes.
In my opinion, Mr. Chairman, moving ahead with strict
government action based upon our current best guess of what we
are thinking is not a wise action. This is especially true in
light of the potential economic and national security
implications that are likely as consequences of restricting our
nation's energy use.
What is needed at this time, Mr. Chairman, is steady and
thoughtful leadership, and I think your hearings demonstrate
that national policy on this issue must evolve commensurately
with the increasing confidence we achieve in our scientific
understanding. Consensus on appropriate action should be the
cornerstone of our national policy on this issue.
The National Academy of Science, upon the authority of a
charter granted by the Congress in 1863, has a mandate that
requires it to advise our government on scientific and
technical matters. The creation of the United Nations
Intergovernmental Panel on Climate Change, which you have
referenced, the IPCC, does not, indeed, should not, extinguish
the mandate of the National Academy to advise our government on
scientific and technical matters.
Let me be clear, Mr. Chairman, that I am not here today to
impugn the work of the scientists associated with the IPCC's
third assessment. Frankly, after conferring with many of the
scientists who are credentialed in the disciplines of
atmospheric and ocean science, I am quite confident that much
of the underlying work contained in the assessment is
relatively sound. However, these same scientists who I have
conferred with caution that the conclusions contained in the
assessment summary, much of which have been reported by the
media, are by no means certain and, at the very least, in need
of scrutiny.
The computer modeling that you referenced in your opening
statement, Mr. Chairman, is a part of our concern. In my
opinion, the President of the National Academy of Science
should be tasked to review the IPCC Third Assessment
conclusions, for the following reasons:
First, The National Academy, through its operating arm, the
National Research Council, has been reviewing the science of
climate change for most of two decades.
Second, many of the scientists involved in the NRC research
on climate change have contributed scientific analysis to the
IPCC's third assessment.
And, finally, the NRC has prepared recent reports
themselves, a synthesis of many other studies, that are useful
guides to the state of knowledge and the requirements for the
scientific path forward.
Mr. Chairman, I have reviewed the recent scientific
reports, as I know you have. The NRC's ``Pathways'' and
``Climate Modeling'' reports raise some profoundly important
questions. Our best policy decisions could turn on answers to
any of them. Now, the ``Pathways'' report stated that presently
available observation and modeling information--again, you have
expressed that concern on climate change--is useful, but cannot
provide the knowledge needed to make informed decisions on the
kinds of critical policies that we would direct.
The most recent National Research Council's report, ``The
Science of Regional and Global Change--Putting Knowledge to
Work,'' which I and Senator Hagel and Senator Murkowski made
available to all Senators in March, reaffirms the very findings
and the very concerns I am expressing. Last week, I met with
Charles Kennel, who co-authored that report and has chaired a
NRC Committee on climate change, also heads up the Scripps
Institution of Oceanography out at La Jolla. He expressed those
concerns, and suggests some approaches to bringing about a
better modeling system.
In addition, Mr. Chairman, the National Academy recognizes
the legitimacy of our concern about the increasing use of
science as an advocacy tool for political agendas by making the
following statement on page 10 of that report:
``Research on how to do more effective, credible, and helpful
scientific assessment is badly needed. Of particular importance
will be the development of assessment processes, that link
knowledge producers and users in a dialog that builds a mutual
understanding of what is needed, what can credibly be said, and
how it can be said in a way that maintains both scientific
credibility, and political legitimacy.''
The National Academy proposes solid recommendations for
implementing an effective research agenda, and I strongly
endorse them.
Mr. Chairman, the National Academy is putting together and
inviting all of us to a high-level, half-day forum at the
Academy's headquarters that I would encourage all of us to
attend. I have encouraged Paul O'Neill of the Treasury to be an
attendee. He is an outspoken person on this issue. Clearly, we
need to consult with our scientists, but in the process, I do
believe we need to build computer models that we can rely on,
and not rely on international models that do not have the
sensitivity to a variety of the concerns, but most importantly,
to the quality of the science involved.
Well, you have urged us to be brief, and I will conclude.
There are important issues to be dealt with here, Mr. Chairman
Thorough vetting by this Committee and others is critical, but
I do believe we have come a long way, but I do not believe that
the science today or the modeling available that brings that
science together will lead us to a basis for sound
policymaking. I think it is our responsibility to bring all of
those tools together.
In visiting with Dr. Kennel the other day, he made it clear
our science is good. The problem is, Mr. Chairman, is that the
science is over here, and the modeling capability is over
there, and we have not put those two together yet. We have all
of those resources in our government. We have the
supercomputers at the Department of Energy, and we have the
brain trust that has been assembled by the National Research
Council through the National Academy of Science. I think it is
our responsibility to not only drive the process that helps put
the proper models together and brings the resources of our
federal government together that will allow us, this Committee
and other committees, the kind of sound decisionmaking based on
good science that the policy for this country demands.
Thank you very much.
The Chairman. Thank you, Senator Craig.
Senator Hagel.
STATEMENT OF HON. CHUCK HAGEL, U.S. SENATOR
FROM NEBRASKA
Senator Hagel. Mr. Chairman, thank you. I, like our
colleague, Senator Craig, am grateful for an opportunity to
come before your Committee this morning and discuss an issue
that I have been deeply involved in over the last several
years. I have come across few issues, Mr. Chairman, more
complex than climate change. What exactly is happening? What is
the science? Are the actions of humans having a real impact on
climate change? What is the future?
Most importantly, I think we asked ourselves, what do we
do? None of these questions have simple answers We do know
there has been climate change since the beginning of time. In
fact, very radical climate change, long before the industrial
revolution or the internal combustion engine.
Climate change, Mr. Chairman, is not new. In addressing
this complicated issue, I start with this premise. Debate over
climate change is not a question of who is for or against the
environment. We all support protecting our involvement. I have
yet to meet a Senator or any public official who wants to leave
dirty air, dirty water, or a degraded environment as the legacy
for his or her children. There may be one, Mr. Chairman. I have
not met him or her.
Over the last 3 months, three scientific working groups of
the Intergovernmental Panel on Climate Change, IPCC, have
released thousands of pages of their work for the IPCC's
assessment. The summaries of those reports are written not by
the scientists, Mr. Chairman, but by U.N. environmental
activists. There is a reason the organization is called the
Intergovernmental Panel on Climate Change. The summaries are
political documents drafted by government representatives after
intense negotiating sessions. In some cases, the very people
sent to represent their countries in writing the IPCC summaries
are later working to negotiate the provisions of the Kyoto
Protocol, so you have the same people defining the problems who
are also trying to create a solution.
The working group reports vary widely in their scientific
conclusions and predictions for global warming during the next
century, but the summaries tend to take very alarmist
viewpoints which are then used to justify the draconian
measures of the Kyoto Protocol. The IPCC summaries are not
science, they are summaries. Furthermore, the predictions made
by the IPCC are based on computer models, which have already
been shown to be inadequate, and vary widely in their
interpretations.
Just as you have noted, Mr. Chairman, as has Senator Craig,
the National Research Council recently issued a report called
the Science of Research nd Global Change, in that they
discussed the abilities of current climate models and here is
what they said,
``The United States today does not have computational and
modeling capability needed to serve society's information needs
for reliable environmental predictions and projections.''
This is what the Clinton administration's Environmental
Protection Agency has to say about computer climate models:
``Virtually all published estimates of how climate change
could change in the U.S. are the result of computer models.
These complicated models are still not accurate enough to
provide a reliable forecast on how climate may change, and
several models often yield very contradictory results.''
This is from President Clinton's EPA.
We know that the earth's climate has, for thousands of
years, gone through cycles of warming and cooling. Ice core
samples from Greenland more than 2 miles deep, dating back more
than 100,000 years, have shown dramatic fluctuations in the
earth's temperature. Since the end of the Ice Age, the last Ice
Age 11,000 years ago, when the earth was 12.6 degrees
Fahrenheit colder than today, there have been several warming
and cooling periods.
Over the last 100 years, surface temperatures have
increased by approximately 1 degree Fahrenheit. However, most
of that increase in surface temperature occurred before 1940,
yet 80 percent of the manmade carbon dioxide was emitted after
1940. Furthermore, while temperatures on the earth's surface
have risen slightly over the last two decades, satellite
temperatures, which are far more accurate, have shown no
warming over the last 20 years.
In fact, from 1979 to 1997, satellite temperatures showed a
slight cooling trend of .04 degrees Fahrenheit. Even the
scientists most associated with global warming, who we will
hear from this morning, Dr. James Hansen, Director of NASA's
Goddard Institute for Space Studies, issued a new analysis last
year which said the emphasis on carbon dioxide emissions may be
misplaced. He will obviously speak for himself, Mr. Chairman.
In 1988, Dr. Hansen testified before a Senate committee
that human activities were causing global warming. In his
report las August, he found that mandate emissions of carbon
dioxide have already been falling. They shrank in 1998 and
1999.
In his report, he stated that other greenhouse gases such
as methane, black soot, CFC's, and the compounds that create
smog maybe causing more damage than carbon dioxide, and efforts
to affect climate change should focus on these other gases
because the technology already exists to capture many of them.
The prospects for having a modest climate impact instead of
disastrous one are quite good, I think, said Dr. Hansen, who
was quoted as saying this in the New York Times on August 19,
2000.
Other preeminent climatologists and meteorologists have
conducted studies which have offered credible alternatives for
the causes of our warming trend. Dr. Sally Belinius, the
director of science programs at Harvard's Center for
Astrophysics has been able to closely correlate changes in the
Sun's brightness with temperature changes on earth. Unlike
climate models, her studies have been able to explain why most
of the earth's warming in the last 100 years occurred before
the significant growth in manmade greenhouse gas emissions.
According to her work, solar activity may be the most direct
factor in global warming.
Mr. Chairman, we know that we are far from understanding
the dynamics of our climate and what stimulates the changes it
undergoes. Increasing research and intensifying our scientific
effort will help lead us to clear answers to the questions,
what is going on, and what is causing it.
In the last Congress, Senators Murkowski, Craig, and I
introduced legislation that would dramatically increase funding
for research. I would like to thank you, Mr. Chairman and your
fellow Commerce Committee members, Senators Dorgan, Brownback,
Burns, Smith, others for cosponsoring that legislation. We will
be updating and reintroducing this legislation in the next few
weeks.
In conclusion, Mr. Chairman, what do we do about climate
change? Nothing? No, I do not believe so. None of us have
advocated that. That would be irresponsible. However, it would
have been equally irresponsible to submit this nation to a
treaty that would have had a disastrous effect on our economy
without having any real impact on global emissions of
greenhouse gases.
President Bush's Interagency Task Force, reviewing climate
change, has been listening to and learning from some of the
world's foremost meteorologists, climatologists, and scientists
in informal meetings. In fact, I believe some of the scientists
we hear from this morning have been in those briefings. He has
said that the administration will soon offer a relevant,
science-based, realistic alternative to the Kyoto treaty. That
is the responsible thing to do.
The United States is still a party to the Framework
Convention on Climate Change, the Rio treaty, which was signed
by the United States and ratified by the U.S. Senate in 1992.
We should go back to the framework of that treaty before the
Berlin mandate of 1994 that excluded developing countries from
participation and laid the groundwork for future international
efforts. If we are creative, and our partners will work with us
in good faith, we can negotiate arrangements that are
responsible, proactive, and realistic.
The United States will need to demonstrate a commitment to
act domestically before it will be able to build international
support for action absent the Kyoto Protocol. It is in our best
interests to create a domestic agenda that will reduce
greenhouse gas emissions without the heavy hand of government
mandates. A forward-looking domestic policy will demonstrate
our commitment, enhance what we genuinely know about climate
change, what we do not know about climate change, create m ore
efficient energy sources, and have the additional effect of
reducing pollutants.
Mr. Chairman, climate change is a serous issue that
deserves serious consideration and, as I stated earlier, our
colleagues, Senators Murkowski, Craig, and I, along with
others, will soon introduce legislation to improve the
scientific knowledge base and lay out positive steps that we
can take now to address that change.
I again add my thanks, congratulations to you, your active
participation, this Committee's oversight, to this effort. It
will take all of us understanding more and more of not just the
sound science dynamic of this, but what do we do about it, and
how do we apply the resources that we have in this country and
in the world to address this issue.
Mr. Chairman, thank you.
The Chairman. I thank you both, Senator Craig and Senator
Hagel. We appreciate your input, and we look forward to working
with you as we address, as you noted, this issue of deep,
growing and serious concern on the part of all Americans. Thank
you very much for being here today.
Senator Stevens would like to make a comment or remarks
before he has to go to another hearing.
STATEMENT OF HON TED STEVENS, U.S. SENATOR
FROM ALASKA
Senator Stevens. Thank you very much, Mr. Chairman. I, too,
congratulate you for these hearings.
I have just returned from the Arctic and our people in
Alaska, along the Arctic Coast, are very worried about the
change that they are observing now, and I intend to take a
group of Senators and staff to Alaska over the Memorial Day
recess to have hearings in Fairbanks with the International
Arctic Research Commission on the question. I wanted to call
that to your attention, and those who are here. I hope many
Senators will join us.
We have faced the problem of moving Native villages that
have been located along the Arctic and West Coast of Alaska for
centuries because they are slowly but surely being inundated by
sea water. That is true of Point Barrow. I talked to some of my
friends who have been out on the ice this year and they tell me
that the ice thickness is probably 8 inches thinner this year
than it was last year, and that we probably are going to have
to move a substantial portion of Point Barrow.
The difficulty is, is that this is a creeping disaster. It
is not a disaster--we are not even sure that it is covered by
the existing disaster law, but very clearly what I want the
Members of the Senate to see along with me and others, and
listen to, some of the international people who have been
working with the International Arctic Research Commission to
try and define what we can expect with regard to the changes in
the Arctic.
As you know, the Northwest Passage will be open for the
third year in a row. We have observed open needs at the North
Pole itself in the Arctic, and I think it is a very serious
thing, particularly for my state and the people who live along
the coastline of my state. I would be glad to invite any member
of the committee who wants to join us.
We intend to stop two or three places and see, actually see
the onslaught of the ocean on these people who live along the
shore in our state, and then we will listen to some of the
people from throughout the Northern Hemisphere and Japan and
Canada and the United States, and try to tell us their
predictions of what we can expect.
We hope we will get some idea of the timing of the impact
on the Arctic, but I do thank you for the time right now, and I
would urge any member of this Committee who wants to join us to
let us know, because we will be leaving for that period.
There will be hearings in Fairbanks for 2 days right after
Memorial Day and before that we will go up and look at the
Arctic in two or three places to see what is happening there.
Thank you very much for the time.
The Chairman. I thank you, Senator Stevens, for what you
had to say. It argues for taking more action than increasing
our modeling capabilities. I thank you, Senator Stevens. I know
you have to go.
Our next panel is--would they please come forward?--Dr.
Venkatachala Ramaswamy, senior scientist, Geophysical Fluids
Dynamics Laboratory, National Oceanic and Atmospheric
Administration, henceforward known as NOAA, Dr. James McCarthy,
director of the Museum of Comparative Zoology at Harvard
University, Dr. Jayant Sathaye, senior scientist at Lawrence
Berkeley National Laboratory, University of California, Dr.
James Hansen, chief of the Goddard Institute for Space Studies
at NASA, and Dr. Richard Lindzen, who is professor at
Massachusetts Institute of Technology in Cambridge.
Dr. Ramaswamy.
STATEMENT OF DR. VENKATACHALA RAMASWAMY, SENIOR SCIENTIST,
GEOPHYSICAL FLUIDS DYNAMICS LABORATORY, NATIONAL OCEANIC AND
ATMOSPHERIC ADMINISTRATION
Dr. Ramaswamy. Mr. Chairman and members of the committee,
good morning. My name is Venkatachala Ramaswamy. I appreciate
the invitation to appear before your Committee and give a
report on the state of the scientific understanding of global
climate change, as documented in the recently concluded IPCC
report. Copies of the summary for policymakers and technical
summary have been distributed, as has been the verbal testimony
with its appendix.
Just a brief word about the assessment. The assessment took
almost 3 years in preparation, between 1998 and 2001, and
represents the work of over 100 scientific authors as well as
several hundred contributing authors worldwide. It is based on
peer-reviewed scientific literature and was carefully
scrutinized by hundreds of scientific peers through an
extensive review process.
I was a coordinating lead author for one of the chapters.
There were 14 chapters in all. I was coordinating lead author
of one of the chapters, and also a member of the drafting team
of the summary for policymakers, which carefully went through
the science contained in the summary. My testimony today
summarizes the understanding as it is manifested in the various
chapters of the report, and as summarized in the summary for
policymakers.
Before starting on the scientific findings of the new
report, I would like to begin with the reiteration of a
fundamental longstanding knowledge, namely, that (1) there is a
natural greenhouse effect which keeps the earth warmer than it
would be otherwise, and (2) greenhouse gases are increasing in
the atmosphere because of human activities, and they are
increasingly trapping more heat in the climate system.
There are many agents which force climate change, and these
factors are greenhouse gas concentrations, tropospheric
aerosols, the sun's energy output, land use change, and the
explosive episodic volcanic eruptions which lead to transitory
increases in stratospheric aerosols.
The characteristics of these forcings can be summarized as:
the long-lived gases have a forcing which is global in extent,
that is, they exert a forcing all over the globe; this is in
contrast to short-lived species, for example, ozone and
aerosols, which vary considerably with region and season. Sun
and volcanoes are natural forcing factors.
One characteristic stands out from the assessment of the
forcings, which is that the estimate and the level of
scientific understanding of greenhouse gases forcing is greater
than for other forcings.
Before discussing the effects of these agents on climate
change, let us state what has the actual climate undergone and
what are our observations of the climate system? Well, the
measurements suggest that there is a growing collective picture
of a warming world over the past century. The global-mean
surface temperatures are up .4 to .8 degrees Celsius over the
past 100 years. In the hand-out, there is a diagram showing the
Northern Hemisphere surface temperatures, culled from the last
140 years, using instrumental record and, then, prior to that,
using proxy records. It shows the degree of rapid increase of
temperatures over the last century compared to both the mean
and the variability expressed on the curve.
Along with the global warming, there have been other
changes which are consistent with this picture, namely the
retreat of mountain glaciers in nonpolar regions, decrease in
the amount of snow cover, the rise in the global average sea
level by 4 to 8 inches.
What are the causes of the observed warming? To analyze
this issue, IPCC resorts to model simulations. Based on
analysis of both the observed record and climate model
simulations using the various forcing agents, it is seen that
there is now new and stronger evidence that most of the
observed warming over the past 50 years is attributable to
human activities.
This is based on the fact there is a better simulation of
the instrumental temperature record when all the forcings,
natural and human-related, are taken into consideration. Only
natural forcings do not lead to a good agreement with the
observations. Neither does the internal variability of the
climate system, as estimated by models, explain the rise in
temperature.
The key factors since the 1995 IPCC report are that there
is now 5 years of additional data which shows a rapid increase
of warming; and the new 1,000-year record, which is based on
proxy data now extending prior to 140 years ago, and that sets
up a context for the changes over the past century. Also,
climate models have evolved and improved since the last IPCC
report.
So now the question is, what could all of this mean for the
future? IPCC considered a range of mission scenarios, and
although the abundances of various greenhouse gases and
aerosols in the future cannot be predicted with a high degree
of confidence, IPCC considered a suite of possible futures
based on considerations of economies, populations, et cetera.
The conclusion from model calculations of the responses to
these various scenarios is that a continued growth in
greenhouse gases is projected to lead to very significant
increases in global mean temperatures and sea level. As far as
numbers are concerned, by 2100 the global mean surface
temperature is projected to increase by 2\1/2\ to 10 degrees
Fahrenheit, considering the range of scenarios, and considering
the modeling uncertainties.
The projected rate of warming from these model simulations
is very likely to be larger than changes that have been
observed over the past 10,000 years. Along with the global-mean
surface temperature change, there is a corresponding projected
sea level rise due to thermal expansion of sea water, on the
order of 4 to 35 inches.
Climate changes in specific regions and years cannot be
predicted with a high degree of confidence but it is likely
that there would be a shift of the climate to a new regime, and
it is likely that the weather could be more variable.
Amidst these projections, a key feature to be borne in
mind, one which has been stated in the earlier IPCC reports and
which is worth reiterating here today, is that the greenhouse
warming can be reversed only very slowly. This is because of
one, the slow rate of removal of many of the gases from the
atmosphere--for example, CO2--because they have long
lifetimes, and second, the slow response of oceans to thermal
perturbations.
Finally, Mr. Chairman, I would like to conclude with an
important remark concerning the IPCC report. This climate
science assessment is the considered viewpoint of hundreds of
scientists worldwide, and is based upon the research results of
the worldwide community that are published in numerous peer-
reviewed scientific journals; there are some 4,000 references
that are referred to in the Working Group 1 report on the
science.
The resulting report contains policy-relevant scientific
information but, of course, makes no policy statements or
recommendations. I will conclude by thanking you for the
invitation to appear today, and to report the findings of the
Working Group 1 on the scientific understanding of global
climate change.
I hope this summary has been helpful to you, Mr. Chairman,
and to the committee. I would be happy to address any
questions. Thank you very much.
[The prepared statement of Dr. Ramaswamy follows:]
Prepared Statement of Dr. Venkatachala Ramaswamy, Senior Scientist,
Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric
Administration
Mr. Chairman: I am a Senior Scientist at NOAA's Geophysical Fluid
Dynamics Laboratory located in Princeton University, Princeton, New
Jersey. I appreciate the invitation to appear before your Committee and
report on the state of the scientific understanding of global climate
change as documented in the recently concluded Intergovernmental Panel
on Climate Change (IPCC) assessment [``Climate Change 2001: The
Scientific Basis'']. The IPCC was set up by the World Meteorological
Organization (WMO) and the United Nations Environment Program (UNEP) to
provide expert assessment of the knowledge and an authoritative
international statement of the scientific understanding on climate
change.
For over 30 years, the Geophysical Fluid Dynamics Laboratory has
been a world leader in the development of numerical models for studying
climate variations and climate change, and has made major contributions
to the understanding of the Earth's climate system. My own research has
involved estimating the natural and human-induced factors that force
climate change, as well as investigating the manner in which the
climate system responds to these factors. For over a decade, I have
been involved in various national and international scientific
assessments. These include National Academy of Science studies, WMO/
UNEP reports on the scientific understanding of the ozone layer and
IPCC climate change science assessments. In the recently concluded IPCC
scientific assignment, I served as the Coordinating Lead Author for the
Chapter on ``Radiative Forcing of Climate Change.'' I was also a member
of the panel which drafted the Summary for Policymakers that was
formally approved in detail and accepted along with the underlying
assessment report at the IPCC Working Group I Plenary session in
January 2001.
I appreciate the invitation to summarize the findings from the IPCC
(2001) report. My information is based on the set of findings in this
report. The assessment took almost three years in preparation and
represents the work of over a hundred scientific authors worldwide. It
is based on scientific literature, and was carefully scrutinized by
hundreds of scientific peers through an extensive peer review process.
My testimony today summarizes the understanding of these authors as
manifested in the report.
Before addressing the new findings of the recent report, two
fundamental points are worthy of note. These have been long-known, are
very well understood, and have been deeply underscored in all previous
IPCC reports and other such scientific summaries.
The ``greenhouse'' effect is real, and is an essential
component of the planet's climate process. A small percentage (roughly
2%) of the atmosphere is, and long has been, composed of greenhouse
gases (water vapor, carbon dioxide, ozone and methane). These
effectively prevent part of the heat radiated by the Earth's surface
from otherwise escaping to space. The global system responds to this
trapped heat with a climate that is warmer, on the average, than it
would be otherwise without the presence of these gases.
In addition to the natural greenhouse effect above, there is a
change underway in the greenhouse radiation balance, namely:
Some greenhouse gases are increasing in the atmosphere
because of human activities and increasingly trapping more heat. Direct
atmospheric measurements made over the past 40-plus years have
documented the steady growth in the atmospheric abundance of carbon
dioxide. In addition to these direct real-time measurements, ice cores
have revealed the atmospheric carbon dioxide concentrations of the
distant past. Measurements using the air bubbles that were trapped
within the layers of accumulating snow show that atmospheric carbon
dioxide has increased by more than 30% over the Industrial Era (since
1750), compared to the relatively constant abundance that it had over
the preceding 750 years of the past millennium [see Figure 2, IPCC
Working Group I Summary for Policymakers, page 6]. The predominant
cause of this increase in carbon dioxide is the combustion of fossil
fuels and the burning of forests. Further, methane abundance has
doubled over the Industrial Era. Other heat-trapping gases are also
increasing as a result of human activities.
The increase in greenhouse gas concentrations in the atmosphere
implies a positive radiative forcing, i.e., a tendency to warm the
climate system [see Figure 3, IPCC Working Group I Summary for
Policymakers, 2001; page 8]. Particles (or aerosols) in the atmosphere
resulting from human activities can also affect climate. Aerosols vary
considerably by region. Some aerosol types act in a sense opposite to
the greenhouse gases and cause a negative forcing or cooling of the
climate system (e.g., sulfate aerosol), while others act in the same
sense and warm the climate (e.g., soot). In contrast to the long-lived
nature of carbon dioxide (centuries), aerosols are short-lived and
removed from the lower atmosphere relatively quickly (within a few
days). Therefore, aerosols exert a long-term forcing on climate only
because their emissions continue each year. In summary, emissions of
greenhouse gases and aerosols due to human activities continue to alter
the atmosphere in ways that are expected to affect the climate. There
are also natural factors which exert a forcing of climate, e.g.,
changes in the Sun's energy output and short-lived (about 1 to 2 years)
aerosols in the stratosphere following episodic and explosive volcanic
eruptions. IPCC evaluated the state of the knowledge and assessed the
level of scientific understanding of each forcing. The level of
understanding and the forcing estimate in the case of the greenhouse
gases are greater than for other forcing agents.
What do these changes in the forcing agents mean for changes in the
climate system? What climate changes have been observed? How well are
the causes of those changes understood? Namely, what are changes due to
natural factors, and what are changes due to the greenhouse-gas
increases? And, what does this understanding potentially imply about
the climate of the future?
These questions bear directly on the scientific points that you
have asked me to address today. In doing so, findings emerging from the
recent IPCC climate science report with respect to measurements,
analyses of climate change to date, and projections of climate change
will be summarized.
There is a growing set of observations that yields a
collective picture of a warming world over the past century. The
global-average surface temperature has increased over the 20th century
by 0.7 to 1.4 degrees Fahrenheit [See Figure 1, IPCC Working Group I
Summary for Policymakers, 2001, page 3]. The average temperature
increase in the Northern Hemisphere over the 20th century is likely to
have been the largest of any century during the past 1,000 years, based
on ``proxy'' data (and their uncertainties) from tree rings, corals,
ice cores, and historical records. Other observed changes are
consistent with this warming. There has been a widespread retreat of
mountain glaciers in non-polar regions. Snow cover and ice extent have
decreased. The global-average sea level has risen between 4 and 8
inches, which is consistent with a warmer ocean occupying more space
because of the thermal expansion of sea water and loss of land ice.
There is new and stronger evidence that most of the
warming observed over the last 50 years is attributable to human
activities. The 1995 IPCC climate-science assessment report concluded:
``The balance of evidence suggests a discernible human influence on
global climate.'' There is now a longer and more closely scrutinized
observed temperature record. Climate models have evolved and improved
significantly since the last assessment. Although many of the sources
of uncertainty identified in 1995 still remain to some degree, new
evidence and improved understanding support the updated conclusion.
Namely, recent analyses have compared the surface temperatures measured
over the last 140 years to those simulated by mathematical models of
the climate system, thereby evaluating the degree to which human
influences can be detected. Both natural climate-change agents (solar
variation and episodic, explosive volcanic eruptions) and human-related
agents (greenhouse gases and fine particles) were included. The natural
climate-change agents alone do not explain the warming in the second
half of the 20th century. The best agreement between observations and
model simulations over the last 140 years is found when both human-
related and natural climate-change agents are included in the
simulations [see Figure 4, IPCC Working Group I Summary for
Policymakers, 2001; page 11]. Further, model simulations indicate that
the warming over the past century is very unlikely to be due to
internal variability alone, i.e., variations within the climate system
that would be expected even in the absence of any forcing. In light of
such new evidence and taking into account the remaining uncertainties,
the IPCC scientists concluded that most of the observed warming over
the last 50 years is likely to have been due to the increase in
greenhouse gas concentrations.
Scenarios of future human activities indicate continued
changes in atmospheric composition throughout the 21st century. The
atmospheric abundances of greenhouse gases and aerosols over the next
100 years cannot be predicted with high confidence, since the future
emissions of these species will depend on many diverse factors, e.g.,
world population, economies, technologies, and human choices, which are
not uniquely specifiable. Rather, the IPCC assessment endeavor aimed at
establishing a set of scenarios of greenhouse gas and aerosol
abundances, with each based on a picture of what the world plausibly
could be over the 21st century. [The emission scenarios were based on
the IPCC Special Report on Emissions Scenarios, 2000; a brief
description of the scenarios appears in the box on page 18 of the
Summary for Policymakers report.] Based on these scenarios and the
estimated uncertainties in climate models, the resulting projection for
the global average temperature increase by the year 2100 ranges from
2.5 to 10 degrees Fahrenheit [see Figure 5, IPCC Working Group I
Summary for Policymakers, 2001; page 14]. Such a projected rate of
warming would be much larger than the observed 20th-century changes and
would very likely be without precedent during at least the last 10,000
years. The corresponding projected increase in global sea level by the
end of this century ranges from 3.5 to 35 inches. Uncertainties in the
understanding of some climate processes make it more difficult to
project meaningfully the corresponding changes in regional climate.
Finally, I would like to relate a basic scientific aspect, one that
has been underscored with very high confidence in all of the IPCC
climate-science assessment reports (1990, 1995, and 2001). It is
repeated here because it is a key (perhaps ``the'' key) aspect of a
greenhouse-gas-induced climate change:
A greenhouse-gas warming could be reversed only very
slowly. This quasi-irreversibility arises because of the slow rate of
removal (centuries) from the atmosphere of many of the greenhouse gases
and because of the slow response of the oceans to thermal changes. For
example, several centuries after carbon dioxide emissions occur, about
a quarter of the increase in the atmospheric concentrations caused by
these emissions is projected to still be in the atmosphere.
Additionally, global average temperature increases and rising sea level
are projected to continue for hundreds of years after a stabilization
of greenhouse gas concentrations (including a stabilization at today's
abundances), owing to the long timescales (centuries) on which the deep
ocean adjusts to climate change.
Let me conclude, Mr. Chairman, with an important remark concerning
the IPCC report. As noted, the IPCC climate-science assessment is the
considered viewpoint of hundreds of scientists worldwide. This
assessment is based upon the research results of the worldwide
community that are published in numerous peer-reviewed scientific
journals. The resulting report contains policy-relevant scientific
information, but makes no policy statements or recommendations. As
such, the three components of the 2001 IPCC Third Assessment Report--
climate science, impacts, and mitigation--are recommended as a key
information source that is available to the Committee as it continues
this important dialogue about climate change and its relation to
humankind.
Thank you for the invitation to appear today. I hope that this
summary has been useful. I would be happy to address any questions.
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The Chairman. Thank you very much.
Dr. McCarthy, welcome.
STATEMENT OF JAMES J. McCARTHY, DIRECTOR, MUSEUM OF COMPARATIVE
ZOOLOGY, HARVARD UNIVERSITY
Dr. McCarthy. Thank you. Good morning, Mr. Chairman, and
members. I am James McCarthy, professor of biological
oceanography at Harvard University, where I am also the
director of the Museum of Comparative Zoology, and I also head
our undergraduate program on environmental science and public
policy, but the reason I am here today, of course, is in my
capacity as the co-chair of the Intergovernmental Panel on
Climate Change Working Group 2. I and a colleague, Osvaldo
Canziani, a meteorologist from Argentina, have co-chaired this
Working Group.
The charge of this Working Group was to assess evidence for
impacts, adaptations and vulnerabilities associated with
climate change. We began this assessment in the autumn of 1997,
and concluded it earlier this spring.
Mr. Chairman, I read the testimony related to climate
change submitted to your Committee last year on three
occasions, May, July, and September. In each case for which
evidence of climate change impacts were cited, we now have
greater confidence that these effects are widespread and more
conclusively linked to climate change.
Some witnesses presented evidence of no change in climate,
or absence of climate change impacts. In my judgment it was the
selection of data for a particular region or particular time
period that led them to these conclusions. This, Mr. Chairman,
is why the work of the IPCC is so important. Some nations have
sponsored and will continue to sponsor studies that may show,
quite correctly, that recent data for their localities do not
show evidence of change. The IPCC focus is on broad patterns
and generalizations that arise from these patterns.
Dr. Neil Lane reported to you that 89 of 99 plants examined
in the District of Columbia are blooming a full week earlier
now than they did a mere 30 years ago, but is this true
everywhere in the globe? Probably not. Were a survey in some
other city to reveal no such change, would this cause one to
doubt that there had been change in Washington, DC.? Certainly,
it would not.
From the IPCC assessment, what is now clear is that this
type of effect in plants and animals over the last few decades
is evident on all continents, and in 80 percent of the
published cases, the change in the distribution of animals or
their biology is consistent with local changes in temperature.
This is strong evidence of biological response to climate
change.
So, we have already seen effects of recent climate change
in ecosystems. While none of these might be classified as
dangerous per se, it is unlikely that they will be reversed
within our lifetime by any action that we might take today to
reduce the rate of climate change. And the rate of climate
change projected for the 21st Century, as we have just heard
from my colleague, is, on average, 2 to 10 times the rate
observed in the 20th Century.
In all likelihood, this projected change will lead to
displacements of species, and perhaps extinctions, especially
in tropical ocean and arctic ecosystems such as we were just
hearing from Senator Stevens. But for the lives and livelihood
of humankind, the largest associated effects of these shifts in
organisms will be in regional agricultural productivity, and in
distribution of disease organisms and their vectors. North
American and Northern Eurasian agriculture may, in fact, be
enhanced, albeit with a northward shift. However, the tropical
and subtropical regions will be hardest hit, with potentially
serious losses of agricultural capacity.
Human systems other than agriculture are also being
affected by climate change, some from general warming, such as
with human health, but others from an increasing frequency,
intensity, and persistence of extreme events.
If climate change is steady and smooth, most of it may be
accommodated or adapted to without great cost, but if the path
is bumpy the story becomes very different. There is no good
news in extreme events. These are inherently disruptive, and
one need only look at the last 5 years to see the global
evidence of this, with floods and mudslides of unprecedented
proportion in Honduras in 1998, where more than 10,000 lives
were lost, and Venezuela in 1999, where more than 25,0000 lives
were lost, and on other continents as well, in Africa, with
Mozambique and Kenya, in Asia with China and North Korea.
Our report, Mr. Chairman, summarizes our assessment of the
published literature on the likely effects of projected changes
in climate on a suite of systems and economic sectors, and for
eight broad regions of the globe we identify the most serious
vulnera-
bilities. The tropical and subtropical regions, many of them
already water-stressed and facing serious questions of food
security, will be hardest hit. This disproportionate impact is
in no small part because these regions, many with developing
countries, are poorly equipped to adapt. In many cases they
lack the infrastructure and simple resources such as in the
case of public health measures. But it is also incorrect to
assume that northern industrialized nations will be spared
serious effects of climate change within their own sovereign
territories. The fraction of their citizens who are most
vulnerable to heat waves, floods, and droughts, will increase.
In summary, Mr. Chairman, some of the climate changes
projected for the future have positive effects: less human
winter mortality in some regions, enhanced crop growth in
others, for example, but most systems and most sectors and most
people will be adversely affected by this climate change. For
most people, the projected rate of change will simply exceed
capacities to adapt to even gradual change, let alone a future
with more frequent, intense, and persistent extreme events.
Our report calls attention to the need to explore all
opportunities to reduce potential adverse effects of climate
change by enhancing adaptive capacity, as with some of the
issues that were being addressed by Senator Stevens.
Thank you again, Mr. Chairman, for this opportunity to
present some of our results to your Committee. I realize that
in addition to the results of the assessment themselves, you
and members of your Committee may have some questions about the
methods and procedures of the IPCC. I refer here specifically
to the last portion of my submitted testimony, in which I
discussed the actual preparation of the Summary for
Policymakers and, with all due respect, I think Senator Hagel
has been misinformed as to how this actually occurs.
In my written testimony, I have remarked on this process,
and I will be happy to discuss further any aspect of the
findings of either the procedures of the IPCC Working Group 2,
or its results, as you wish.
Thank you.
[The prepared statement of Dr. McCarthy follows:]
Prepared Statement of James J. McCarthy, Director,
Museum of Comparative Zoology, Harvard University
Thank you, Senator McCain, for this opportunity to address the
Committee on Commerce, Science, and Transportation. My name is James J.
McCarthy, and I am a Professor of Oceanography, the Director of the
Museum of Comparative Zoology, and the Head Tutor for undergraduate
students studying Environmental Science and Public Policy at Harvard
University.
For nearly four years I have co-chaired Working Group II (WG II) of
the Intergovernmental Panel on Climate Change (IPCC). The focus of this
working group has been to assess potential impacts, adaptations, and
vulnerabilities to climate change. In my letter of invitation to this
hearing you have asked that I comment on the results and conclusions of
the IPCC WG II and other related issues that I wish to bring to the
attention of the Committee.
The new WG II report, Climate Change 2001: Impacts, Adaptation, and
Vulnerability, is the most comprehensive and up-to-date scientific
assessment of the consequences of, and adaptation responses to, climate
change. The report:
evaluates evidence that recent observed changes in climate
have already affected a variety of physical and biological systems.
makes a detailed study of the vulnerabilities of human
populations to future climate change, including associated sea-level
rise and changes in the frequency and intensity of climate extremes
such as floods, droughts, heat waves and windstorms, and taking into
account potential impacts on water resources, agriculture and food
security, human health, coastal and other types of settlements, and
economic activities.
assesses the potential responses of natural environments
and the wildlife that inhabit them to future climate change and
identifies environments at particular risk.
considers how adaptation to climate change might lessen
adverse impacts or enhance beneficial impacts.
provides an overview of the vulnerabilities and adaptation
possibilities by major region of the world (Africa, Asia, Australia/New
Zealand, Europe, Latin America, Polar Regions, and Small Island
States).
contrasts the different vulnerabilities of the developed
and developing parts of the world and explores the implications for
sustainable development and equity concerns.
Research on climate impacts has grown considerably during the five
years since the last IPCC assessment, and much has been learned
regarding the potential risk of damage associated with projected
climate change. In particular, this research has added new
understanding of vulnerabilities to climate change across a spectrum of
ecological systems (forests, grasslands, wetlands, rivers, lakes and
marine environments) and human systems (agriculture, water resources,
coastal resources, human health, financial institutions, and human
settlements).
Observational evidence of changes has accumulated in many physical
and biological systems (e.g. glacial melting, shifts in geographic
ranges of plant and animal species, and changes in plant and animal
biology) that are highly consistent with warming observed in recent
decades. These observations are adding to our knowledge of the
sensitivity of affected systems to changes in climate and can help us
to understand the vulnerability of systems to the greater and more
rapid climate changes projected for the 21st century. A number of
unique systems are increasingly recognized as especially vulnerable to
climate change (e.g. glaciers, coral reefs and atolls, mangroves,
boreal and tropical forests, polar and alpine ecosystems, prairie
wetlands, and remnant native grasslands). In addition, climate change
is expected to threaten some species with greater probability of
extinction. Potential changes in the frequency, intensity, and
persistence of climate extremes (e.g. heat waves, heavy precipitation,
and drought) and in climate variability (e.g. El Nino--Southern
Oscillation) are emerging as key determinants of future impacts and
vulnerability. The many interactions of climate change with other
stresses on the environment and human populations, as well as linkages
between climate change and sustainable development, are increasingly
emphasized in recent research and preliminary insights from these
important efforts are reflected in the report.
The value of adaptation measures to diminish the risk of damage
from future climate change, and from present climate variability, was
recognized in previous assessments and is confirmed and expanded upon
in the new assessment. Understanding of the determinants of adaptive
capacity has advanced and confirms the conclusion that developing
countries, particularly the least developed countries, have lesser
capacity to adapt than do developed countries. This condition results
in relatively high vulnerability to damaging effects of climate change
in these countries.
more specific new findings
The effects of recent climate change are now clearly evident in
many natural systems. Changes in the distribution of species as
documented in the fossil record have long been used as an important
diagnostic of past climate. In addition, it is well known that the
seasonal behavior of many species, such as migrations and reproductive
behavior (e.g. flowering time and egg laying) are sensitive to
temperature. In the past few decades substantial changes in these
characteristics have been noted for many species, and for 80% of the
cases for which such changes could plausibly be linked to temperature,
the biotic changes were consistent with changes in regional
temperature.
The documented changes in Arctic sea ice cover, both its thinning
and its shrinkage during summer, affect polar ecosystems. The shrinkage
that is occurring has averaged 3% per decade for the entire Arctic over
the last three decades. Throughout Northern Hemisphere freshwater
ecosystems the ice-free season is now nearly 2 weeks longer than it was
a century ago, which is consistent with an average annual temperature
increase of about 1+ C. Increased access for ships is a positive aspect
of this trend. During the summer of 2000, for the first time in
recorded history, a RCMP ship transited the Northwest Passage without
touching ice. With summer ice-free conditions in the Arctic expanding
poleward, ecosystems will shift accordingly. Marine mammals, such as
walrus, certain seals, and the polar bear have evolved with a
dependence on ice for successful feeding and rearing of their young. As
summer ice retreats from land earlier in the season and reaches greater
maximum distances, the success of these species will be challenged.
Now, in the span of a single human generation, observations point to a
coherent shift in the pattern of temperature sensitive systems on all
continents.
Many human systems are also inherently sensitive to climate change.
Examples in the IPCC report include:
changes in potential crop yields, especially reductions in
most tropical and subtropical regions.
changes in water availability, especially losses in the
sub-tropics.
an increase in the number of people exposed to vector born
diseases like malaria and water borne diseases like cholera.
increased losses of lives, livelihood, and property from
heavy rains and sea level rise.
Already the increased frequency and intensity of extreme
precipitation events has taken a heavy toll. Devastation caused by
floods and mudslides in tropical to temperate regions on all continents
in the last decade has been without precedent. While a gradual increase
in temperature might be accommodated by many natural and human systems,
the projected increases in frequency, intensity, and persistence of
extreme events has the potential to be enormously disruptive. Moreover
the impacts of these changes will fall disproportionately on the
poorest peoples. While this may be an obvious conclusion when comparing
certain developed and developing countries, it will also be true within
a developed country. The fraction of the population that is vulnerable
to an extreme heat wave or flood will increase with the severity of the
extreme event.
Many of the most devastating aspects of climate change will occur
in tropical and subtropical regions, where 70% of the world's
population live, many in developing countries. These are the regions
that will be the most water stressed, suffer the greatest potential
losses of agricultural capacity, and be most vulnerable to the expanded
ranges of certain infectious diseases. Even allowing for possible
benefits from climate change in some temperate regions, such as net
gains in potential crop yields, the negative aspects of climate change
in subtropical and tropical regions are likely to offset these positive
aspects even assuming there would be no infrastructure or financial
obstacle to the distribution of resources, i.e. food, moved from one
region to another.
Thus the following are evident in the recent IPCC assessment:
responses to climate change are already occurring in
natural and human systems.
it is highly likely that climate changes in the 21st
century will be 2--10 faster than those of the 19th century.
increased frequency and severity of extreme events will be
costly to natural and human systems.
Given the inertia in human system-climate system linkages, these
findings lead inevitably to the conclusion that even the most
optimistic scenarios for mitigating future climate change are unlikely
to prevent significant damage from occurring. This is not to say that
mitigation efforts such as a fully implemented Kyoto Protocol won't be
effective; rather that their effect won't be evident for decades. Thus,
an important finding of the IPCC is that adaptation will be absolutely
necessary to minimize damage that is projected from future climate
change. Limitations in adaptive capacity will make some regions and
some peoples of lesser means more vulnerable to the impacts of climate
change. Natural systems will be affected in all regions from polar to
tropical on all continents. Human systems will, however, be most
vulnerable to climate change in Africa, Latin America, and Asia where
current adaptive capacity is low.
If we wish to minimize the loss of lives, livelihoods and property
that will occur during our inevitable transition to a warmer world, it
is imperative that we redouble efforts to both minimize the emissions
of fossil fuel combustion products and prepare peoples and systems as
best we can for the disruption that will ensue with the climate change
that is now projected for the 21st century.
comments on the ipcc process
Nowhere can one find a process that produces a report on the
understanding of a broad area of science that is more inclusive in its
coverage of contemporary scientific views, or more broadly vetted by
the scholarly community than with the IPCC. The basis of the assessment
is the peer-reviewed published scientific literature. Every effort is
made to be thorough, and serious attention is given to disparate
results and conclusions in this literature. To the extent possible,
degrees of likelihood are assigned to summary statements, especially
those on projected climate conditions and climate impacts.
Currently about 100 governments participate in the IPCC, and all
were invited to propose the names of experts who could serve as authors
of this report. More than one thousand nominations were received for WG
II authors, with supporting documentation listing the nominees'
publications in scientific journals. It should be noted that the
authors of IPCC reports work without financial compensation for their
efforts on behalf of the IPCC.
The report of WG II was drafted between July 1998 and February 2001
by 183 Lead Authors. In addition, 243 Contributing Authors, from nearly
70 countries, submitted draft text and information to the Lead Authors.
Drafts of the report were circulated twice for review, first to experts
and a second time to both experts and governments. Comments received
from 440 reviewers were carefully analyzed and assimilated in a revised
the document, with guidance provided by 33 Review Editors. The full
report was then condensed into a 70-page manuscript, known as a
Technical Summary (TS), and it was then further condensed into a 20-
page manuscript known as a Summary for Policy Makers (SPM). The TS and
SPM (along with a revision of the full report that reflected the
earlier government and expert review) were then sent out for a final
review coordinated by governments.
Comments from this final review were then used to prepare a
revision of the SPM and TS, and a plenary of the Working Group was
convened to consider final approval of the SPM. This involved about 150
delegates from 100 nations, drawn from each nation's departments and
ministries of state and science. The plenary met for four days in
Geneva (Switzerland) in February 2001 to vet the SPM line-by-line,
proceeding to the next line only when all delegates agreed to do so.
While the science that underpins SPM was clear to its authors as
their document was taken to the plenary for approval, the plenary is
actually the final stage in this process of clarifying the message for
policy makers. Discussions in the course of the plenary called
attention to words and sentences that were perceived to be unclear by a
delegate, and suggested changes were made as long as they were not
inconsistent with the underlying science. By the conclusion of the
meeting the Summary for Policymakers was approved in detail and the
full report accepted by all delegations.
The Working Group Summary for Policy Makers is attached. It and
related documents are available in pdf format at www.usgcrp.gov/ipcc.
The Summary for Policymakers.--Climate Change 2001: Impacts,
Adaptation, and Vulnerability is being maintained in Committee files.
The Chairman. Thank you, Dr. McCarthy.
Dr. Lindzen.
STATEMENT OF DR. RICHARD S. LINDZEN, MASSACHUSETTS
INSTITUTE OF TECHNOLOGY
Dr. Lindzen. Thank you, Senator McCain, for the opportunity
to appear before this Committee. I am a member of the NAS, and
I also participated in the third assessment report as a lead
author on chapter 7.
The Chairman. Chapter 7 was?
Dr. Lindzen. The physics of climate. I come here usually
designated as a skeptic. I am not sure what that means. I think
in dealing with this, people are correct in saying that the
science is complex, and I think the complexity is not only
intrinsic, but has also resulted from the presentation of the
issue, which in many ways has forced confusion and
irrationality to dominate the discussion. It is presented as a
multifaceted problem involving atmospheric composition, heat
transfer, weather, temperature, ocean dynamics, hydrology, sea
level, glaciology, ecology, and even epidemiology. All of these
are subjects filled with uncertainty.
On the other hand, and I do not say any of my colleagues
here today have done this, but you know that it is frequently
said the science is settled. This is often said without any
statement as to exactly what is meant by this, and what
relevance it has to the forecast being made. The IPCC itself as
a document is not particularly extreme, and I agree with my
colleagues that it tends to present the science more or less as
it is for better or for worse, but in the popular eye it is
used as a mantra. It inevitably is used by people who wish to
convince others that the science is settled, it is supported by
thousands of scientists, and that this relieves them of the
necessity to explain the science.
In point of fact, there are quite a few areas of agreement,
and I think very few, if any of them, in any convincing way
point to disaster, despite scenario creations of the type that
Dr. McCarthy spoke of. For example, Dr. Ramaswamy mentioned
things that are agreed upon, that the temperature has
increased, that the CO2 has increased, that CO2
is more likely to cause warming than cooling, and I would add
to that that man, like the butterfly, has some impact on
climate.
What is frequently not realized is, the statements are as
consistent with the statement that there will not be a problem
as there will be a problem. They have very little substantive
content, and yet they are perceived as having content.
In addition, we tend to raise issues that are different
from warming, per se. To be sure, a few degrees of warming, or
a degree does not particularly frighten the public. All of us
who have had the extraordinary experience of day and night,
winter and summer, have experienced far greater changes, so we
go to what I think used to be called show-stoppers, increased
weather extremes, increased variability, rising sea levels, and
so on.
Now, I mention here a lot of things where there is
widespread agreement on the science--that is hardly alarmist--
but I will mention one specifically, and you can read some of
the others in the testimony, and that has to do with increased
weather extremes and disturbances. Here, the science for at
least 40 years has noted that at least outside the tropics the
main source of generating storms is the difference in
temperature between the equator and pole.
Virtually all model predictions of global warming predict
this will go down, and yet you have people always mentioning
storminess. The cartoon I offer you emphasizes this. It should
be going down, not up, by the basic physics.
When you see extremes in weather in any given season, it is
because the wind changes from the north to south, and the
extremes you see relate to how cold could a north wind be. That
depends on how cold the Arctic is and how warm the tropics are.
In other words, it depends on the pole-to-equator temperature
difference. We are simultaneously hearing that these extremes
will increase while the difference goes down. That is
impossible, so in some sense alarmism has become a very
important part of the issue, rather than the facts themselves.
The Kyoto agreement is also something that has been
presented with utter confusion. I think there is widespread
agreement that the Kyoto agreement, if adhered to, would have
very little impact on climate. The estimates are, if you
expected 4 degrees, you believed such models, you would knock
it down to about 3.8.
In part, this is due to the fact that the Kyoto agreement
applies only to the developed world, but even if extended to
the whole world, harming the developing world rather severely,
because that is at the heart of all claims that the developing
world is more vulnerable. You are always more vulnerable if you
are poor. You might knock it down from 4 to 3. In other words,
if you expect severe warming, you will still have severe
warming, so as a policy in itself, it seemed fairly ill-advised
and ineffective.
Now, it has been mentioned that computer models are at the
basis of much of our understanding, if you can call it that,
and it is certainly at the basis of scenario-building. It has
been mentioned, for example, that we are now surer that a large
part of climate change is due to man. This is based on computer
models. It is not a verification. You have to assume natural
and internal variability generated by models is the same as it
is in nature, and so we have circular projections.
This is part of our whole scenario system, where you no
longer ask computer models to be correct. It is widely
acknowledged that they are not. What you ask instead is that
the projections be possible, and here the 1992 framework
convention which we signed commits us to something called a
precautionary principle, which now says all you have to do is
suggest something is possible in order to need to act upon it.
I think that is a rather dangerous procedure, in any event,
with such things as ill-defined possibilities and so on come to
the IPCC, and we have heard from two people who participated
very heavily in it, much more than I did, but there are a
number of things with the IPCC that you should keep in mind.
First of all, even the summary, which does not adequately
represent the text, is encouraging the media, the advocacy
groups to misrepresent the summary. When the summary offers a
range, however ill-advised, the media picked it up. When the
summary says some part may be due to man, this is regarded as a
smoking gun, even though it says no more than the advertising
claim, savings up to 40 percent, which in fact permits them to
overcharge you, so the use of language which conveys different
meaning to layman and scientist is a serious issue.
The summary itself glosses over the text. There is no way
you can conveniently summarize 1,000 pages in 13. With respect
to the chapter on the physics, we went to considerable pains
pointing out all the problems of the models. The summary simply
concludes, understanding of climate processes and their
incorporation in climate models have improved, including water
vapor, sea ice dynamics, and ocean heat transport. That is not
exactly the gist, and certainly with respect to clouds the
statement was, all models completely fail to replicate clouds.
The statement that the IPCC represents hundreds of
scientists does ignore the fact that hundreds of scientists are
never asked. Each of them works on a few pages. The summary,
the fact that the summary was worked on by a subset of about--
you told me it was about 10 lead authors out of the hundreds
ignores the fact that the summary's draft, which was prepared
by these, itself was significantly changed in Shanghai.
I can testify that the preparation of the report itself was
not only contentious, which is normal, but even after people
with very different views had agreed, there was still pressure
not to criticize models, to exaggerate the progress, and so on.
There is the final thing in the document that has such a
technical importance on policy, that there are examples where
the full text is modified long after the individual authors
have signed off. I would say it is a very disturbing fact that
the text was essentially complete last August, but is released,
and as far as I know is still not released, long after the
summary is released.
In any event, I do not think any of this is surprising. The
IPCC was created in essence to support the negotiations, and
without the negotiations, without the alarm, there would be no
IPCC. It is not unusual that an organization has its own
interests. The question I would like to go to and finish with
is, where do we go from here?
I think it is extremely important in science policy, and
that is where I have my own provincial interest, that we figure
out how to support science without providing incentives for
alarmism. I think you see here today an example that a field
that promotes alarmism will get added attention. How do we
assure scientists that they can find out that something is not
alarming and still have support to figure out how nature works,
instead of addressing it toward alarmism?
I think that is something that will definitely benefit
future generations, the better understanding of nature, and
this will far outweigh the benefits of any, if any, of ill-
thought-out attempts to regulate nature in the absence of such
understanding.
With respect to policy, I think the National Research
Council in 1992 had a very lengthy report, Policy Implications
of Greenhouse Warming, and their main conclusion was, carry out
only those actions which can be justified independently of any
putative anthropogenic global warming, and here I would add
that you not identify things with climate change unless they
can be shown, unlike Kyoto, to have a significant impact on
climate, otherwise it just becomes a coat hook.
Now, looking back at the picture on the first page of my
testimony, you will notice they always picture emissions as
being black. Remember that CO2 is odorless and
invisible, is essential to life, nontoxic, and is a normal
product of breathing. When you portray it as black, you are
already misleading the public.
Thank you.
[The prepared statement of Dr. Lindzen follows:]
Prepared Statement of Dr. Richard S. Lindzen, Massachussetts
Institute of Technology
I wish to thank Senator McCain and the Commerce Committee for the
opportunity to clarify the nature of consensus and skepticism in the
Climate Debate. I have been involved in climate and climate related
research for over thirty years during which time I have held
professorships at the University of Chicago, Harvard University and
MIT. I am a member of the National Academy of Sciences, and the author
or coauthor of over 200 papers and books. I have also been a
participant in the proceedings of the IPCC (the United Nation's
Intergovernmental Panel on Climate Change). The questions I wish to
address are the following: What can we agree on and what are the
implications of this agreement? What are the critical areas of
disagreement? What is the origin of popular perceptions? I hope it will
become clear that the designation, `skeptic,' simply confuses an issue
where popular perceptions are based in significant measure on misuse of
language as well as misunderstanding of science. Indeed, the
identification of some scientists as `skeptics' permits others to
appear `mainstream' while denying views held by the so-called
`skeptics' even when these views represent the predominant views of the
field.
Climate change is a complex issue where simplification tends to
lead to confusion, and where understanding requires thought and effort.
Judging from treatments of this issue in the press, the public has
difficulty dealing with numerical magnitudes and focuses instead on
signs (increasing v. decreasing); science places crucial emphasis on
both signs and magnitudes. To quote the great 19th Century English
scientist, Lord Kelvin, ``When you can measure what you are speaking
about and express it in numbers, you know something about it; but when
you cannot measure it, when you cannot express it in numbers, your
knowledge is of a meager and unsatisfactory kind.''
As it turns out, much of what informed scientists agree upon is
barely quantitative at all:
that global mean temperature has probably increased over
the past century,
that CO2 in the atmosphere has increased over
the same period,
that the added CO2 is more likely to have
caused global mean temperature to increase rather than decrease, and
that man, like the butterfly, has some impact on climate.
Such statements have little relevance to policy, unless
quantification shows significance.
The media and advocacy groups have, however, taken this agreement
to mean that the same scientists must also agree that global warming
``will lead to rising sea waters, droughts and agriculture disasters in
the future if unchecked'' (CNN). According to Deb Callahan, president
of the League of Conservation Voters, ``Science clearly shows that we
are experiencing devastating impacts because of carbon dioxide
pollution.'' (Carbon dioxide, as a `pollutant' is rather singular in
that it is a natural product of respiration, non-toxic, and essential
for life.) The accompanying cartoon suggests implications for severe
weather, the ecosystem, and presumably plague, floods and droughts (as
well as the profound politicization of the issue). Scientists who do
not agree with the catastrophe scenarios are assumed to disagree with
the basic statements. This is not only untrue, but absurdly stupid.
Indeed, the whole issue of consensus and skeptics is a bit of a red
herring. If, as the news media regularly report, global warming is the
increase in temperature caused by man's emissions of CO2
that will give rise to rising sea levels, floods, droughts, weather
extremes of all sorts, plagues, species elimination, and so on, then it
is safe to say that global warming consists in so many aspects, that
widespread agreement on all of them would be suspect ab initio. If it
truly existed, it would be evidence of a thoroughly debased field. In
truth, neither the full text of the IPCC documents nor even the
summaries claim any such agreement. Those who insist that the science
is settled should be required to state exactly what science they feel
is settled. In all likelihood, it will turn out to be something trivial
and without policy implications except to those who bizarrely subscribe
to the so-called precautionary principle--a matter I will return to
later. (Ian Bowles, former senior science advisor on environmental
issues at the NSC, published such a remark on 22 April in the Boston
Globe: ``the basic link between carbon emissions, accumulation of
greenhouse gases in the atmosphere, and the phenomenon of climate
change is not seriously disputed in the scientific community.'' I think
it is fair to say that statements concerning matters of such complexity
that are not disputed are also likely to be lacking in policy relevant
content. However, some policymakers apparently think otherwise in a
cultural split that may be worthy of the late C.P. Snow's attention.)
The thought that there might be a central question, whose
resolution would settle matters, is, of course, inviting, and there
might, in fact, be some basis for optimism. While determining whether
temperature has increased or not is not such a question, the
determination of climate sensitivity might be. Rather little serious
attention has been given to this matter (though I will mention some in
the course of this testimony). However, even ignoring this central
question, there actually is much that can be learned simply by sticking
to matters where there is widespread agreement. For example, there is
widespread agreement
that CO2 levels have increased from about
280ppm to 360ppm over the past century, and, that combined with
increases in other greenhouse gases, this brings us about half way to
the radiative forcing associated with a doubling of CO2
without any evidence of enhanced human misery.
that the increase in global mean temperature over the past
century is about 1F which is smaller than the normal interannual
variability for smaller regions like North America and Europe, and
comparable to the interannual variability for the globe. Which is to
say that temperature is always changing, which is why it has proven so
difficult to demonstrate human agency.
that doubling CO2 alone will only lead to about
a 2F increase in global mean temperature. Predictions of greater
warming due to doubling CO2 are based on positive feedbacks
from poorly handled water vapor and clouds (the atmosphere's main
greenhouse substances) in current computer models. Such positive
feedbacks have neither empirical nor theoretical foundations. Their
existence, however, suggests a poorly designed earth which responds to
perturbations by making things worse.
that the most important energy source for extratropical
storms is the temperature difference between the tropics and the poles
which is predicted by computer models to decrease with global warming.
This also implies reduced temperature variation associated with weather
since such variations result from air moving from one latitude to
another. Consistent with this, even the IPCC Policymakers Summary notes
that no significant trends have been identified in tropical or
extratropical storm intensity and frequence. Nor have trends been found
in tornados, hail events or thunder days.
that warming is likely to be concentrated in winters and
at night. This is an empirical result based on data from the past
century. It represents what is on the whole a beneficial pattern.
that temperature increases observed thus far are less than
what models have suggested should have occurred even if they were
totally due to increasing greenhouse emissions. The invocation of very
uncertain (and unmeasured) aerosol effects is frequently used to
disguise this. Such an invocation makes it impossible to check models.
Rather, one is reduced to the claim that it is possible that models are
correct.
that claims that man has contributed any of the observed
warming (ie attribution) are based on the assumption that models
correctly predict natural variability. Such claims, therefore, do not
constitute independent verifications of models. Note that natural
variability does not require any external forcing--natural or
anthropogenic.
that large computer climate models are unable to even
simulate major features of past climate such as the 100 thousand year
cycles of ice ages that have dominated climate for the past 700
thousand years, and the very warm climates of the Miocene, Eocene, and
Cretaceous. Neither do they do well at accounting for shorter period
and less dramatic phenomena like El Ninos, quasi-biennial oscillations,
or intraseasonal oscillations--all of which are well documented in the
data, and important contributors to natural variability.
that major past climate changes were either uncorrelated
with changes in CO2 or were characterized by temperature
changes which preceded changes in CO2 by 100's to thousands
of years.
that increases in temperature on the order of 1F are not
catastrophic and may be beneficial.
that Kyoto, fully implemented, will have little detectable
impact on climate regardless of what one expects for warming. This is
partly due to the fact that Kyoto will apply only to developed nations.
However, if one expected large global warming, even the extension of
Kyoto to developing nations would still leave one with large warming.
None of the above points to catastrophic consequences from
increasing CO2. Most point towards, and all are consistent
with minimal impacts. Moreover, the last item provides a definitive
disconnect between Kyoto and science. Should a catastrophic scenario
prove correct, Kyoto will not prevent it. If we view Kyoto as an
insurance policy, it is a policy where the premium appears to exceed
the potential damages, and where the coverage extends to only a small
fraction of the potential damages. Does anyone really want this? I
suspect not. Given the rejection of the extensive US concessions at the
Hague, it would appear that the Europeans do not want the treaty, but
would prefer that the US take the blame for ending the foolishness. As
a practical matter, a large part of the response to any climate change,
natural or anthropogenic, will be adaptation, and that adaptation is
best served by wealth.
Our own research suggests the presence of a major negative feedback
involving clouds and water vapor, where models have completely failed
to simulate observations (to the point of getting the sign wrong for
crucial dependences). If we are right, then models are greatly
exaggerating sensitivity to increasing CO2. Even if we are
not right (which is always possible in science; for example, IPCC
estimates of warming trends for the past twenty years were almost
immediately acknowledged to be wrong--so too were claims for arctic ice
thinning ), the failure of models to simulate observations makes it
even less likely that models are a reliable tool for predicting
climate.
This brings one to what is probably the major point of
disagreement:
Can one trust computer climate models to correctly predict the
response to increasing CO2?
As the accompanying cartoon suggests, our experience with weather
forecasts is not particularly encouraging though it may be argued that
the prediction of gross climate changes is not as demanding as
predicting the detailed weather. Even here, the situation is nuanced.
From the perspective of the precautionary principle, it suffices to
believe that the existence of a computer prediction of an adverse
situation means that such an outcome is possible rather than correct in
order to take `action.' The burden of proof has shifted to proving that
the computer prediction is wrong. Such an approach effectively deprives
society of science's capacity to solve problems and answer questions.
Unfortunately, the incentive structure in today's scientific enterprise
contributes to this impasse. Scientists associate public recognition of
the relevance of their subject with support, and relevance has come to
be identified with alarming the public. It is only human for scientists
to wish for support and recognition, and the broad agreement among
scientists that climate change is a serious issue must be viewed from
this human perspective. Indeed, public perceptions have significantly
influenced the science itself. Meteorologists, oceanographers,
hydrologists and others at MIT have all been redesignated climate
scientists--indicating the degree to which scientists have hitched
their futures to this issue.
That said, it has become common to deal with the science by
referring to the IPCC `scientific consensus.' Claiming the agreement of
thousands of scientists is certainly easier than trying to understand
the issue or to respond to scientific questions; it also effectively
intimidates most citizens. However, the invocation of the IPCC is more
a mantra than a proper reflection on that flawed document. The
following points should be kept in mind. (Note that almost all reading
and coverage of the IPCC is restricted to the highly publicized
Summaries for Policymakers which are written by representatives from
governments, NGO's and business; the full reports, written by
participating scientists, are largely ignored.) In what follows, I will
largely restrict myself to the report of Working Group I (on the
science). Working Groups II and III dealt with impacts and responses.
The media reports rarely reflect what is actually in the
Summary. The media generally replace the IPCC range of `possible'
temperature increases with `as much as' the maximum--despite the highly
unlikely nature of the maximum. The range, itself, assumes,
unjustifiably, that at least some of the computer models must be
correct. However, there is evidence that even the bottom of the range
is an overestimate. (A recent study at MIT found that the likelihood of
actual change being smaller than the IPCC lower bound was 17 times more
likely than that the upper range would even be reached, and even this
study assumed natural variability to be what computer models predicted,
thus exaggerating the role of anthropogenic forcing.) The media report
storminess as a consequence despite the admission in the summary of no
such observed relation. To be sure, the summary still claims that such
a relation may emerge--despite the fact that the underlying physics
suggests the opposite. The media's emphasis on increased storminess,
rising sea levels, etc. is based not on any science, but rather on the
fact that such features have more graphic impact than the rather small
increases in temperature. People who have experienced day and night and
winter and summer have experienced far greater changes in temperature,
and retirement to the sun belt rather than the Northwest Territory
represents an overt preference for warmth.
The summary does not reflect the full document (which
still has not been released although it was basically completed last
August). For example, I worked on Chapter 7, Physical Processes. This
chapter dealt with the nature of the basic processes which determine
the response of climate, and found numerous problems with model
treatments--including those of clouds and water vapor. The chapter was
summarized with the following sentence: ``Understanding of climate
processes and their incorporation in climate models have improved,
including water vapour, sea-ice dynamics, and ocean heat transport.''
The vast majority of participants played no role in
preparing the summary, and were not asked for agreement.
The draft of the Policymakers Summary was significantly
modified at Shanghai. The IPCC, in response to the fact that the
Policymakers Summary was not prepared by participating scientists,
claimed that the draft of the Summary was prepared by a (selected)
subset of the 14 coordinating lead authors. However, the final version
of the summary differed significantly from the draft. For example the
draft concluded the following concerning attribution:
From the body of evidence since IPCC (1996), we conclude that there
has been a discernible human influence on global climate. Studies are
beginning to separate the contributions to observed climate change
attributable to individual external influences, both anthropogenic and
natural. This work suggests that anthropogenic greenhouse gases are a
substantial contributor to the observed warming, especially over the
past 30 years. However, the accuracy of these estimates continues to be
limited by uncertainties in estimates of internal variability, natural
and anthropogenic forcing, and the climate response to external
forcing.
The version that emerged from Shanghai concludes instead:
In the light of new evidence and taking into account the remaining
uncertainties, most of the observed warming over the last 50 years is
likely to have been due to the increase in greenhouse gas
concentrations.
In point of fact, there may not have been any significant warming
in the last 60 years. Moreover, such warming as may have occurred was
associated with jumps that are inconsistent with greenhouse warming.
The preparation of the report, itself, was subject to
pressure. There were usually several people working on every few pages.
Naturally there were disagreements, but these were usually hammered out
in a civilized manner. However, throughout the drafting sessions, IPCC
`coordinators' would go around insisting that criticism of models be
toned down, and that `motherhood' statements be inserted to the effect
that models might still be correct despite the cited faults. Refusals
were occasionally met with ad hominem attacks. I personally witnessed
coauthors forced to assert their `green' credentials in defense of
their statements.
None of the above should be surprising. The IPCC was created to
support the negotiations concerning CO2 emission reductions.
Although the press frequently refers to the hundreds and even thousands
of participants as the world's leading climate scientists, such a claim
is misleading on several grounds. First, climate science, itself, has
traditionally been a scientific backwater. There is little question
that the best science students traditionally went into physics, math
and, more recently, computer science. Thus, speaking of `thousands' of
the world's leading climate scientists is not especially meaningful.
Even within climate science, most of the top researchers (at least in
the US) avoid the IPCC because it is extremely time consuming and non-
productive. Somewhat ashamedly I must admit to being the only active
participant in my department. None of this matters a great deal to the
IPCC. As a UN activity, it is far more important to have participants
from a hundred countries--many of which have almost no active efforts
in climate research. For most of these participants, involvement with
the IPCC gains them prestige beyond what would normally be available,
and these, not surprisingly, are likely to be particularly supportive
of the IPCC. Finally, judging from the Citation Index, the leaders of
the IPCC process like Sir John Houghton, Dr. Robert Watson, and Prof.
Bert Bolin have never been major contributors to basic climate
research. They are, however, enthusiasts for the negotiating process
without which there would be no IPCC, which is to say that the IPCC
represents an interest in its own right. Of course, this hardly
distinguishes the IPCC from other organizations.
The question of where do we go from here is an obvious and
important one. From my provincial perspective, an important priority
should be given to figuring out how to support and encourage science
(and basic science underlying climate in particular) while removing
incentives to promote alarmism. The benefits of leaving future
generations a better understanding of nature would far outweigh the
benefits (if any) of ill thought out attempts to regulate nature in the
absence of such understanding. With respect to any policy, the advice
given in the 1992 report of the NRC, Policy Implications of Greenhouse
Warming, remains relevant: carry out only those actions which can be
justified independently of any putative anthropogenic global warming.
Here, I would urge that even such actions not be identified with
climate unless they can be shown to significantly impact the radiative
forcing of climate. On neither ground--independent justification or
climatic relevance--is Kyoto appropriate.
The Chairman. Thank you.
Dr. Sathaye.
STATEMENT OF DR. JAYANT A. SATHAYE, SENIOR SCIENTIST, LAWRENCE
BERKELEY NATIONAL LABORATORY,
UNIVERSITY OF CALIFORNIA
Dr. Sathaye. Thank you, Mr. Chairman, for inviting me.
I am a senior scientist at the Lawrence Berkeley National
Laboratory operated by the University of California. I have
worked as a Coordinating Lead Author of one of the chapters,
the Third Assessment Report of the Third Working Group, and I
have also served in a similar capacity on other IPCC reports
over the last 7 years or so.
The main points that I want to make today deal with two
segments, two time periods, one dealing with the reduction of
near-term annual greenhouse gas emissions, and the second
dealing with the long-term stabilization of climate change.
With regards to the near-term annual greenhouse gas emissions,
the IPCC concluded that there were many technologies already
available in the marketplace, which have the potential to
reduce global greenhouse gas emissions from 2010 to 2020 to
levels below those of 2000 and this is something you pointed
out, Mr. Chairman in your statement. About half of the
reduction potential can be achieved with direct benefits,
exceeding the direct cost, and the other half at a net direct
cost of $100 per ton of carbon equivalent.
Now, this may seem somewhat optimistic and, indeed, if you
tried to deploy these technologies in the marketplace you would
encounter a number of different barriers, and these barriers
include things like subsidized prices, world capital markets,
lack of access to information and so forth, and we have a whole
chapter in the IPCC that deals with just these issues. The
implications of these barriers are that it will take time in
order to implement the technologies that are available to us,
and they will add to the cost of implementing these
technologies as well.
Let me go on to talk about another aspect of the near-term
cost, and this deals with a whole array of studies that have
been done about the cost to various industrial economies if
they were to meet the levels of emissions constraints specified
in the Kyoto Protocol. The studies showed that the cost to the
U.S. economy would range between 0.4 to 2 percent of the U.S.
GDP in the year 2010.
Now, there are a number of ways the cost could be reduced
and this, too, has been referred to earlier. One of the more
important ways this cost could be reduced is through full
emissions trading across industrialized countries. Just by that
approach alone, these costs could be reduced by 50 percent, and
we have experience with this, with sulphur dioxide trading
within the United States and, indeed, that was a very effective
approach to reducing sulphur dioxide emissions from power
plants in the United States. But the cost can be further
reduced if you pursue carbon dioxide projects in developing
countries and also include land use change and forestry options
in addition to other technologies.
Now, Dr. Lindzen just mentioned this question about
pursuing approaches that also address other benefits that you
might derive from mitigation actions and so if you pursue
options that also reduce local pollutants, this could have a
double or joint benefit whereby you achieve reductions in local
pollutants as well as reduction of greenhouse gases.
Let me now turn to the second topic, which has to do with
the stabilization of long-term atmospheric greenhouse gas
concentrations. What the IPCC report concludes is that in this
case as well, the technological options that we need in order
to stabilize climate at levels of 450 parts per million, for
instance, which is about 20 percent over the levels in the year
2000, those technological options are known as well, so we are
not looking for exotic technologies in order to stabilize
climate change if we decide that that is what we want to do
over the long term.
In terms of the cost of achieving such stabilization, it
will depend upon what stabilization level we pick as well as
the emissions pathway to that stabilization level, and least-
cost studies show that the lower the stabilization level, the
more it will reach that level. The lower stabilization level
means you begin earlier to decrease emissions as well.
Stabilization will require the participation of all
countries. All IPCC emission scenarios show one trend
consistently, that you cannot stabilize unless all countries
participate in this process. The emission scenarios also
indicate that conventional oil and gas resources will be
severely depleted by mid-century or earlier. This is true for
all emission scenarios that IPCC has looked at, and what this
implies is that there will be an opportunity, or opportunities
to shift or make a transition to less-carbon-intensive energy
sources and technologies as the conventional oil and gas
resources are depleted.
Finally, Mr. Chairman, in order to achieve these kinds of
technological breakthroughs, investments in energy R&D, the
transfer existing technologies is going to play a critical role
not just in the United States but worldwide if climate is to be
stabilized.
Let me also make a couple of remarks about the IPCC
process. I think all of us here have participated in that
process to some degree, and perhaps one thing that is probably
worth clearing up is that the IPCC is engaged in reviews of
studies, research studies that have already been done.
There is no new research being done within the IPCC work,
and it is completely compatible with national governments, or
national institutions carrying out research as mandated, or as
required by governments on their own, and I think this is
important to remember, that if there was no research done,
there would be nothing for the IPCC to review.
The second point about the IPCC is that we are providing
information to negotiators, but we also are providing
summarized information to all concerned. It is not just to the
government, the negotiators. It goes to academics, it goes to
students, and can be shared with everyone.
Lastly, you can do studies and nobody ever reads them, they
go on bookshelves, and you can do studies in which the
governments participate actively. In the IPCC process there is,
indeed, some give-and-take, but we make sure that the content
of the IPCC report remains in the summaries and, given that, I
think there is a value to that process of consensus-building
and pulling together this information in a summarized form.
Let me conclude with that, and thank you again, Mr.
Chairman for inviting me.
[The prepared statement of Dr. Sathaye follows:]
Prepared Statement of Dr. Jayant A. Sathaye\1\, Senior Scientist,
Lawrence Berkeley National Laboratory, University of California
summary
The IPCC WG III review of studies on climate change mitigation
describes the potential and costs of technologies, practices, and
policies to (1) reduce near-term annual greenhouse gas (GHG) emissions,
and (2) stabilize atmospheric GHG concentrations over the long-term.
---------------------------------------------------------------------------
\1\ The remarks in this statement represent my personal views, and
not necessarily those of the Lawrence Berkeley National Laboratory or
the University of California.
---------------------------------------------------------------------------
Reduction of Near-term Annual GHG Emissions:
1. Significant unanticipated technical progress relevant to
greenhouse gas reductions has been achieved since the IPCC released its
Second Assessment Report in 1996.
2. Technologies such as efficient hybrid engine cars, fuel cells,
underground carbon dioxide storage, and many others have the potential
to reduce global GHG emissions in 2010--2020 to below 2000 levels.
3. In the absence of barriers, studies suggest that about half of
the above emissions reduction potential can be achieved with direct
benefits exceeding direct costs, and the other half at a net direct
cost of up to US $ 100/t Ceq (at 1998 prices). Overcoming barriers such
as subsidized prices, lack of access to information and financing, and
ill defined property rights will incur additional costs, which in some
cases may be substantial.
4. National responses can be more effective if deployed as a
portfolio of policy instruments to reduce greenhouse gas emissions.
5. About a dozen studies based on models of the global economy
estimate that costs to the US economy of meeting GHG emissions levels
noted in the Kyoto Protocol vary from 0.4-2.0% of 2010 GDP.
6. Assuming full GHG emissions trading both within and across
industrialized countries, these studies show that costs can be reduced
to less than half the above values.
7. Costs may be further reduced through implementation of carbon
offset projects in developing countries, and land use, land-use change
and forestry (LULUCF) activities, mitigation options that also reduce
local pollutants, and revenue neutral carbon taxes.
Stabilization of Long-term (2100+) Atmospheric GHG Concentrations:
8. Widespread use of known technological options could achieve a
broad range of atmospheric carbon dioxide stabilization levels such as
550, 450 ppmv or below (compared to 368 ppmv in 2000) over the next 100
years or more, if the type of barriers noted in item 3 above could be
overcome.
9. The cost of achieving stabilization will depend on the emissions
pathway and the targeted stabilization level. Least-cost studies show
that decreasing the stabilization target makes annual emissions peak
earlier and at lower levels before beginning a gradual decline, and
vice versa. Estimated costs of stabilizing carbon dioxide
concentrations increase steeply as the level declines below 550 ppmv.
10. Stabilization will require the participation of all countries.
Two-thirds of IPCC Post-SRES scenarios show that annual GHG emissions
per capita from industrialized countries decline to levels below those
of developing countries by 2050.
11. IPCC emissions scenarios indicate a severe depletion of
conventional oil and gas resources by mid-century or earlier. This
offers an opportunity for a transition to less-carbon-intensive energy
sources and technologies.
12. Investment in energy R&D, the transfer and adoption of existing
technology, and technological and social innovation will be required to
foster the penetration of these energy sources and improved
technologies.
results and conclusions
Mr. Chairman, thank you for inviting me to speak about the findings
of the Working Group (WG) III on Climate Change 2001: Mitigation of the
Intergovernmental Panel on Climate Change (IPCC). I served as a
Coordinating Lead Author of the Chapter on Barriers, Opportunities, and
Market Potential of Technologies and Practices of the WG III report,
and an author of the Synthesis Report, and have participated in the
discussions and writing of their Summaries for Policy Makers (SPM). My
remarks today are based largely on the SPM findings and the contents of
the underlying report. In this statement, I have focused on the near-
and long-term potential for, and costs and benefits of, reducing
reenhouse gas emissions.
1. There are many low cost technological options to reduce near-
term emissions, but barriers to their deployment exist.
Significant technical progress relevant to the potential for
greenhouse gas emission reductions has been made since 1995 and has
been faster than anticipated. Net emissions reductions could be
achieved through, inter-alia, improved production and use of energy,
shift to low- or no-carbon technologies, carbon removal and storage,
and improved land-use, land-use change and forestry (LULUCF) practices.
Relevant advances are taking place in a wide range of technologies at
different stages of development, ranging from the market introduction
of efficient hybrid engine cars to the advancement of fuel cell
technology, and the demonstration of underground carbon dioxide
storage.
The successful implementation of greenhouse gas mitigation options
would need to overcome many technical, economic, political, cultural,
social, behavioral and/or institutional barriers which prevent the full
exploitation of the technological, economic and social opportunities of
these mitigation options (Figure 1). The potential mitigation
opportunities and types of barriers vary by region and sector, and over
time. In the industrialized countries, future opportunities lie
primarily in removing social and behavioral barriers, in countries with
economies in transition, in price rationalization; and in developing
countries, in price rationalization, increased access to data and
information, availability of advanced technologies, financial
resources, and training and capacity building. Most countries could
benefit from innovative financing and institutional reform and removing
barriers to trade.
National responses to climate change can be more effective if
deployed as a portfolio of policy instruments to limit or reduce
greenhouse gas emissions. The portfolio may include--according to
national circumstances- emissions/carbon/energy taxes, tradable or non-
tradable permits, subsidies, deposit/refund systems, technology or
performance standards, product bans, voluntary agreements, government
spending and investment, and support for research and development.
Annual global emissions reductions of 1.9-2.6 GtCeq, and 3.6--5.0
GtCeq per year could be achieved by 2010 and 2020 respectively, with
half of these reductions being realized with direct benefits exceeding
direct costs, and the other half at a net direct cost of up to US$100/
tCeq (at 1998 prices). Depending on the emissions scenario this could
allow global emissions to be reduced below 2000 levels in 2010-2020
(Table 1). These cost estimates are derived using discount rates in the
range of 5 to 12 percent, consistent with public sector discount rates,
but lower than private internal rates of return, thus affecting the
rate of adoption of these technologies by private entities. Realising
these reductions involves, among other things, additional
implementation costs, which in some cases may be substantial, the
possible need for supporting policies, increased research and
development, and effective technology transfer.
2. Based on models of the global economy the cost estimates of
meeting GHG emissions levels noted in the Kyoto Protocol vary
considerably both within and across regions.
Models show that the Kyoto mechanisms can reduce costs to Annex
II\2\ countries. Global modeling studies show national marginal costs
to meet the Kyoto emissions levels range from about US$20/tC up to
US$600/tC without trading, and from about US$15/tC up to US$150/tC with
Annex B\3\ trading. Figure 2 shows the range of GDP losses estimated in
these studies in 2010. The cost reductions and GDP losses from these
mechanisms may depend on the details of implementation, including the
compatibility of domestic and international mechanisms, constraints,
and transaction costs. These costs can be further reduced through use
of the Clean Development Mechanism, LULUCF activities, by including the
non-carbon dioxide gases, identifying and implementing options that
produce ancillary benefits, and identifying double dividend
opportunities, e.g., carbon taxes or auctioned permits may be used to
finance reductions in existing distortionary taxes, reducing the
economic cost of achieving greenhouse gas reductions.
---------------------------------------------------------------------------
\2\ Annex II: Countries listed in the Annex II of the UN Framework
Convention on Climate Change. Annex II list includes the United States
and 23 other original members of the Organization for Economic
Cooperation and Development (OECD), plus the European Union.
\3\ Annex B: Annex I countries that are listed in the Kyoto
Protocol to take on commitments to limit their emissions.
---------------------------------------------------------------------------
Emission constraints in Annex I\4\ countries have well established,
albeit varied ``spill over'' effects on non-Annex I countries,
including:
---------------------------------------------------------------------------
\4\ Annex I: Annex II countries plus the countries designated as
Economies in Transition.
---------------------------------------------------------------------------
Oil-exporting, non-Annex I countries: The study reporting the
lowest costs, reported reductions in projected GDP of 0.2% with no
emissions trading, and less than 0.05% with Annex B emissions trading
in 2010. The study reporting the highest costs shows reductions of
projected oil revenues of 25% with no emissions trading, and 13% with
Annex B emissions trading in 2010.
Other non-Annex I countries may be adversely affected by reductions
in demand for their exports to OECD nations and by the price increase
of those carbon-intensive and other products they continue to import,
but may benefit from the reduction in fuel prices, increased exports of
carbon-intensive products and the transfer of environmentally sound
technologies and know how.
3. Technology development and diffusion are an important component
of cost-effective stabilization.
Transfer of existing technologies and the development and transfer
of new technologies could play a critical role in reducing the cost of
stabilizing greenhouse gas concentrations. Transfer of technologies
between countries and regions could widen the choice of options at the
regional level and economies of scale and learning will lower the costs
of their adoption. Governments through sound economic policy, and
regulatory frameworks, transparency and political stability could
create an enabling environment for private and public sector technology
transfers and adequate human and organizational capacity is essential
at every stage to increase the flow, and improve the quality, of
technologies. In addition, networking among private and public
stakeholders, and focusing on products and techniques with multiple
ancillary benefits, that meet or adapt to local needs and priorities,
is essential for most effective technology transfers.
IPCC emissions scenarios indicate that conventional oil and gas
resources will be mostly used up by mid-century irrespective of actions
to address climate change (Figure 3). This will necessitate a different
pattern of energy resource development and an increase in energy R&D
with the goal of accelerating the development and deployment of
advanced energy technologies. Given that the carbon in proven
conventional oil and gas reserves, or in conventional oil resources, is
limited, this may imply a change in the energy mix and the introduction
of new sources of energy during the 21st century. If so, the choice of
energy mix and associated investment will determine whether, and if so,
at what level and cost, greenhouse concentrations can be stabilized.
Opportunities that exist in the near term are the fruits of past
investments in energy R&D; therefore, further investments in energy R&D
will be required to maintain the flow of improved energy technologies
throughout the 21st century.
Technological and social innovation could raise the social and
economic potential of mitigation options beyond that of current
markets. In the longer term, such innovations may shift preferences and
cultural norms towards lower-emitting and sustainable behaviors.
4. Both the pathway to stabilization of atmospheric GHG
concentrations and the stabilization target itself are key determinants
of mitigation costs
Stabilization levels depend more on cumulative rather than year-by-
year emissions. A gradual near-term transition away from the world's
present energy system towards a less carbon-emitting economy minimizes
costs associated with premature retirement of existing capital stock
and provides time for technology development, and avoids premature
lock-in to early versions of rapidly developing low-emission
technology, where-as more rapid near-term action would decrease
environmental and human risks associated with projected changes in
climate and may stimulate more rapid deployment of existing low-
emission technologies and provide strong near-term incentives to future
technological changes.
Studies show that the costs of stabilizing carbon dioxide
concentrations in the atmosphere increase as the stabilization level
declines (Figure 4). While there is a moderate increase in the costs
when passing from a 750 ppm to a 550 ppm concentration stabilization
level, there is a larger increase in costs passing from 550 ppm to 450
ppm unless the emissions in the baseline scenario are very low.
However, these studies did not incorporate carbon sequestration, non-
carbon dioxide gases and did not examine the possible effect of more
ambitious targets on induced technological change.
Countries and regions will have to choose their own path to a low
emissions future, where decision-making is essentially a sequential
process under uncertainty. Most model results indicate that known
technological options could achieve a broad range of atmospheric carbon
dioxide stabilization levels, such as 550 ppm or 450 ppm and below over
the next 100 years or more, but implementation would require associated
socio-economic and institutional changes. However, no single sector or
technology option could provide all of the emissions reductions needed.
A prudent risk management strategy requires a careful consideration of
the economic and environmental consequences, their likelihood and
society's attitude toward risk.
Stabilization of atmospheric GHG levels will require the
participation of all countries in the long term. Two-thirds of IPCC
Post-SRES scenarios show that annual GHG emissions per capita from
industrialized countries decline to levels below those of developing
countries by 2050.
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The Chairman. Thank you very much.
Dr. Hansen, welcome.
STATEMENT OF DR. JAMES E. HANSEN, DIRECTOR, GODDARD INSTITUTE
FOR SPACE STUDIES, NATIONAL AERONAUTICS AND SPACE
ADMINISTRATION
Dr. Hansen. Thank you, Mr. Chairman.
I will talk about future climate. The most popular climate
projection is the business-as-usual scenario. It leads to
dramatic climate change later in the century. It provides a
useful warning of what is possible if greenhouse gases grow
more and more rapidly.
Four of my colleagues and I recently described an
alternative scenario for climate change in the 21st Century
which we think is a useful complement to the business-as-usual
scenario. We assert that a brighter climate future is not only
possible but can be achieved with actions that make good sense,
independent of global warming.
This alternative scenario can be explained with the help of
my bar chart for the forcing agents that underlie climate
change. These are the climate forcings that exist today,
relative to 1850. Carbon dioxide is the largest climate-forcing
at 1.4 watts per meter squared, but these other greenhouse
gases, methane, CFC's, low-level ozone, and nitrous oxide
together cause a forcing that is equally as large. Methane,
when you include its effects on other gases, causes a forcing
half as large as CO2, and then there are these
aerosols. Aerosols are fine particles in the atmosphere, liquid
or solid particles.
Black carbon, which comes from diesel fuel and coal-
burning, causes a warming. Sulphate and organic carbon, which
come from fossil fuel burning, cause cooling. All of these
particles have some effect on cloud properties, which tends to
cause a cooling. However, it is rather uncertain, the magnitude
of that cooling.
The question is, how will these forcings change in the
future? We could keep the additional climate forcing the next
50 years as small as 1 watt per meter squared by means of two
actions. First, we must stop any further net growth of the non-
CO2 forcings, several of which are air pollution.
Their growth needs to be stopped anyhow for reasons of public
health. Second, CO2 emissions can continue, but the
emissions rate should be no larger than it is today, preferably
declining slowly. The resulting forcing of 1 watt would be
expected to cause some climate change, but less than 1 degree
Celsius warming in 50 years.
So how can we stop the growth of these non-CO2
forcings? Black carbon is a product of incomplete combustion.
You can see it in the exhaust of diesel trucks. The microscopic
particles are like tiny sponges. They soak up toxic organics
and other aerosols. They are so tiny that when breathed in they
penetrate human tissue deeply. Some of the smallest enter the
bloodstream. These particulates cause respiratory and cardiac
problems, asthma, acute bronchitis. With tens of thousands of
deaths per year in the United States, also in Europe, where the
health costs of particulate air pollution has been estimated at
1.6 percent of the gross domestic products.
In the developing world the costs are staggering. In India,
approximately 270,000 children under the age of 5 die per year
from acute respiratory infections caused by air pollution. Most
of that pollution arises in household burning of field residue,
cow dung, biomass, coal, for cooking and heating. There is now
a brown cloud of pollution mushrooming from India. You can see
it against the Himalayas.
There is a similar story for ozone. It is a pollutant that
causes tens of billions of dollars of damage. We could stop its
further growth. We have the technology to do that.
There is a somewhat different story for methane, but there
are practical steps that could be taken to stop the growth of
methane also.
The bottom line is that we have only one atmosphere, and it
is a global atmosphere. My personal opinion is that we need to
reduce the pollution that we are putting into it for a number
of reasons, especially human health, and in the process we can
help prevent the non-CO2 climate forcing from
increasing.
In the United States, for example, we could reduce diesel
emissions and other soot emissions. We might also work with
developing countries to help reduce their pollution. One
possible long-term solution there would be electrification, a
source of clean energy.
Finally, I must also address CO2. It is the
hardest part of the problem, but not as hard as it is often
made out to be. In 1998, global CO2 emissions
declined slightly. In 1999 CO2 emissions declined
again. In 2000 I believe that they declined again, but the
numbers are not yet in.
The Chairman. Doctor, why did those emissions decline?
Dr. Hansen. The primary reason was China. Choking on its
pollution, it reduced the amount of coal-burning, replaced coal
power plants with gas power plants. Emissions from the United
States actually increased in those years, but there are other
countries where they are making efforts at renewable energies,
and that is having some effect.
The Chairman. Thank you.
Dr. Hansen. Now, that is just the trend that is needed to
achieve our alternative scenario with only moderate climate
change. In the near term, my opinion is that this trend can be
maintained via concerted efforts toward increased energy
efficiency and increased use of renewable energy sources. On
the long-term, most energy experts suggest that we would need a
significant increasing contribution from some energy source
that produces little or no CO2.
In my written testimony, I note several possibilities,
which include zero emission coal, nuclear power, and a
combination of solar energy and hydrogen and fuel cells. Each
possibility has pros and cons, and I am not recommending
policy. R&D is needed. It will be up to the public, via their
representatives, to make choices. My point is that such
possibilities exist, so the concept of the alternative scenario
with only a modest climate change is a viable possibility.
Thank you. I would like to include in the record copies of
my final three references in my official testimony. These
discuss this topic in more detail, but in a plain language,
which I think might be helpful.
[The prepared statement of Dr. Hansen follows:]
Prepared Statement of Dr. James E. Hansen, Director, Goddard Institute
for Space Studies, National Aeronautics and Space Administration
1. preface
Mr. Chairman and Members of the Committee: I appreciate the
opportunity to clarify the paper I co-authored with four other
scientists on climate change in the 21st century, published in
Proceedings of the National Academy of Sciences (1). In that paper, we
define an ``alternative scenario'' for the forcing agents that cause
climate change. The alternative scenario gives equal emphasis to
reducing air pollution and to a continued slow downtrend in CO2
emissions. This scenario produces only a moderate climate change in the
next 50 years. We suggest that the climate forcings in this scenario
can be achieved via pragmatic actions that make good sense for a
variety of reasons. Collateral benefits include improvements in human
health, agricultural productivity, and greater energy self-sufficiency.
Our alternative scenario differs markedly from the ``business as
usual'' scenarios of the Intergovernmental Panel on Climate Change
(IPCC), which have received the greatest attention among the plethora
of IPCC scenarios. However, I emphasize that our paper is not a
criticism of IPCC. The IPCC reports (2), produced by hundreds of
outstanding scientists, provide an invaluable assessment of the status
of scientific understanding of climate change.
Although our research has relevance to public issues, it is not our
job to suggest policies. Our objective is to provide scientific
information that the public and their representatives can use to help
choose wise policies. Thus our aim is to provide relevant information
on the forcing agents that drive climate change that is as quantitative
and as clear as the data permit.
2. introduction: basic concepts
The Earth's climate fluctuates from year to year and century to
century, just as the weather fluctuates from day to day. It is a
chaotic system, so changes occur without any forcing, but the chaotic
changes are limited in magnitude. The climate also responds to
forcings. If the sun brightens, a natural forcing, the Earth becomes
warmer. If a large volcano spews aerosols into the stratosphere, these
small particles reflect sunlight away and the Earth tends to cool.
There are also human-made forcings.
We measure forcings in watts per square meter (W/m2).
For example, all the human-made greenhouse gases now cause a forcing of
more than 2 W/m2. It is as if we have placed two miniature
Christmas tree bulbs over every square meter of the Earth's surface.
That is equivalent to increasing the brightness of the sun by about 1
percent.
We understand reasonably well how sensitive the Earth's climate is
to a forcing. Our most reliable measure comes from the history of the
Earth. We can compare the current warm period, which has existed
several thousand years, to the previous ice age, about 20,000 years ago
(3, 4, 5). We know the composition of the atmosphere during the ice age
from bubbles of air that were trapped as the ice sheets on Greenland
and Antarctica built up from snowfall. There was less carbon dioxide
(CO2) and less methane (CH4), but more dust in
the air. The surface was different then, with ice sheets covering
Canada and parts of Europe, different distributions of vegetation, even
the coast-lines differed because sea level was 300 feet lower. These
changes, as summarized in Figure 1, caused a negative climate forcing
of about 6\1/2\ W/m2. That forcing maintained a planet that
was 5+ C colder than today. This empirical information implies that
climate sensitivity is about \3/4\+ C per watt of forcing. Climate
models have about the same sensitivity, which provides encouraging
agreement between the real world and the complex computer models that
we use to predict how climate may change in the future.
There is another important concept to understand. The climate
cannot respond immediately to a forcing, because of the long time
needed to warm the ocean. It takes a few decades to achieve just half
of the equilibrium climate response to a forcing. Even in 100 years the
response may be only 60-90 percent complete (5). This long response
time complicates the problem for policy-makers. It means that we can
put into the pipeline climate change that will only emerge during the
lives of our children and grandchildren. Therefore we must be alert to
detect and understand climate change early on, so that the most
appropriate policies can be adopted.
3. past climate forcings and climate change
The climate forcings that exist today are summarized in Figure 2
(1). The greenhouse gases, on the left, have a positive forcing, which
would tend to cause warming. CO2 has the largest forcing,
but CH4, when its indirect effect on other gases is
included, causes a forcing half as large as that of CO2.
CO2 is likely to be increasingly dominant in the future, but
the other forcings are not negligible.
Aerosols, in the middle of the figure, are fine particles in the
air. Some of these, such as sulfate, which comes from the sulfur
released in coal and oil burning, are white, so they scatter sunlight
and cause a cooling. Black carbon (soot) is a product of incomplete
combustion, especially of diesel fuel and coal. Soot absorbs sunlight
and thus warms the planet. Aerosols tend to increase the number of
cloud droplets, thus making the clouds brighter and longer-lived. All
of the aerosol effects have large uncertainty bars, because our
measurements are inadequate and our understanding of aerosol processes
is limited.
If we accepted these estimates at face value, despite their large
uncertainties, we would conclude that, climate forcing has increased by
1.7 W/m2 since the Industrial Revolution began [the error
bars, in some cases subjective, yield an uncertainty in the net forcing
of 1 W/m2]. The equilibrium warming from a forcing of 1.7 W/
m2 is 1.2-1.3+ C. However, because of the ocean's long
response time, we would expect a global warming to date of only about
\3/4\+ C. An energy imbalance of 0.7 W/m2 remains with that
much more energy coming into the planet than going out. This means
there is another \1/2\+ C global warming already in the pipeline--it
will occur even if atmospheric composition remains fixed at today's
values.
The climate forcings are known more precisely for the past 50
years, especially during the past 25 years of satellite measurements.
Our best estimates are shown in Figure 3. The history of the
tropospheric aerosol forcing, which involves partial cancellation of
positive and negative forcings, is uncertain because of the absence of
measurements. However, the GHG and stratospheric aerosol forcings,
which are large forcings during this period, are known accurately.
When we use these forcings in a global climate model (3) to
calculate the climate change (6), the results are consistent with
observations (Figure 4). We make five model runs, because of the chaos
in the climate system. The red curve is the average of the five runs.
The black dots are observations. The Earth's stratosphere cools as a
result of ozone depletion and CO2 increase, but it warms
after volcanic eruptions. The troposphere and the surface warm because
of the predominantly positive forcing by increases of greenhouse gases,
in reasonably good agreement with observations.
The fourth panel in Figure 4 is important. It shows that the
simulated planet has an increasing energy imbalance with space. There
is more energy coming into the planet, from the sun, than there is
energy going out. The calculated imbalance today is about 0.7 W/
m2. This, as mentioned above, implies that there is about
0.5+ C additional global warming already in the pipeline, even if the
atmospheric composition does not change further. An important
confirmation of this energy imbalance has occurred recently with the
discovery that the deep ocean is warming. That study (7) shows that the
ocean took up heat at an average rate of 0.3 W/m2 during the
past 50 years, which is reasonably consistent with the predictions from
climate models. Observed global sea ice cover has also decreased as the
models predict.
There are many sources of uncertainty in the climate simulations
and their interpretation. Principal among the uncertainties are climate
sensitivity (the Goddard Institute for Space Studies model sensitivity
is 3+ C for doubled CO2, but actual sensitivity could be as
small as 2+ C or as large as 4+ C for doubled CO2), the
climate forcing scenario (aerosol changes are very poorly measured),
and the simulated heat storage in the ocean (which depends upon the
realism of the ocean circulation and mixing). It is possible to find
other combinations of these ``parameters'' that yield satisfactory
agreement with observed climate change. Nevertheless, the observed
positive heat storage in the ocean is consistent with and provides some
confirmation of the estimated climate forcing of 1.7 1 W/
m2. Because these parameters in our model are obtained from
first principles and are consistent with our understanding of the real
world, we believe that it is meaningful to extend the simulations into
the future, as we do in the following section. Such projections will
become more reliable and precise in the future if we obtain better
measurements and understanding of the climate forcings, more accurate
and complete measures of climate change, especially heat storage in the
ocean, and as we employ more realistic climate models, especially of
ocean circulation.
4. scenarios for 2000-2050
We extend our climate model simulations into the future for two
climate forcing scenarios shown in Figure 5. In the popular ``business-
as-usual'' scenario, which the media focuses upon, the climate forcing
increases by almost 3 W/m2 in the next 50 years. This leads
to additional global warming of about 1.5+ C by 2050 and several
degrees by 2100. Such a scenario, with exponential growth of the
greenhouse forcing, leads to predictions of dramatic climate change and
serious impacts on society.
The ``alternative scenario'' assumes that global use of fossil
fuels will continue at about today's rate, with an increase of 75 ppm
in airborne CO2 by 2050. Depending on the rate of CO2
uptake by the ocean and biosphere this may require a small downtrend in
CO2 emissions, which would be a helpful trend for obtaining
climate stabilization later in the century. The alternative scenario
also assumes that there will be no net growth of the other forcings: in
somewhat over-simplified terminology, ``air pollution'' is not allowed
to get any worse that it is today. The added climate forcing in the
alternative scenario is just over 1 W/m2 in the next 50
years.
The alternative scenario results in an additional global warming in
the next 50 years of about \3/4\+ C, much less than for the business-
as-usual scenario. In addition, the rate of stratospheric cooling
declines in the alternative scenario (top panel of Figure 5), and in
fact the lower stratospheric temperature would probably level out
because of expected stratospheric ozone recovery (not included in this
simulation). The planetary energy imbalance increases by only about \1/
4\ W/m2 in the alternative scenario, compared with almost 1
W/m2 in the business-as-usual scenario. In other words, our
children will leave their children a debt (\3/4\+ C additional warming
in the pipeline) that is only slightly more than the amount of
unrealized warming (\1/2\+ C) hanging over our heads now.
Figure 6 is a cartoon summarizing the two parts of the alternative
scenario. First, the scenario keeps the added CO2 forcing at
about 1 W/m2, which requires that annual increases in
atmospheric CO2 concentrations be similar to those in the
past decade. The precise scenario that we employ has the CO2
growth rate declining slowly during these 50 years, thus making it more
feasible to achieve still lower growth rates in the second half of the
century and an eventual ``soft landing'' for climate change. Second,
the net growth of other climate forcings is assumed to cease. The most
important of these ``other'' forcings are methane, tropospheric ozone,
and black carbon aerosols. Specific trace gas scenarios used in our
global climate model simulations are shown in Figure 7.
In the following two sections we provide data that helps provide an
indication of how difficult or easy it may be to achieve the elements
of the alternative scenario.
5. alternative scenario: air pollution
One of the two requirements for achieving the alternative scenario
is to stop the growth of non-CO2 forcings. Principally, that
means to halt, or even better reverse, the growth of black carbon
(soot), tropospheric ozone (O3) and methane
(CH4). These can loosely be described as air pollution,
although in dilute amounts methane is not harmful to health. Black
carbon, with adsorbed organic carbon, nitrates and sulfates, and
tropospheric ozone are principal ingredients in air pollution.
Black carbon (soot). Black carbon aerosols, except in the extreme
case of exhaust puffs from very dirty diesel trucks or buses, are
invisibly small particles. They are like tiny sponges that soak up
toxic organic material that is also a product of fossil fuel
combustion. The aerosols are so small that they penetrate human tissue
deeply when breathed into the lungs, and some of the tiniest particles
enter the blood stream. Particulate air pollution, including black
carbon aerosol, has been increasingly implicated in respiratory and
cardiac problems. A recent study in Europe (8) estimated that air
pollution caused annually 40,000 deaths, 25,000 new cases of chronic
bronchitis, 290,000 episodes of bronchitis in children, and 500,000
asthma attacks in France, Switzerland and Austria alone, with a net
cost from the human health impacts equal to 1.6 percent of their gross
domestic product. Pollution levels and health effects in the United
States are at a comparable level. Primary sources of black carbon in
the West are diesel fuels and coal burning.
The human costs of particulate air pollution in the developing
world are staggering. A study recently published (9) concluded that
about 270,000 Indian children under the age of five die per year from
acute respiratory infections arising from particulate air pollution. In
this case the air pollution is caused mainly by low temperature
inefficient burning of field residue, cow dung, biomass and coal within
households for the purpose of cooking and heating. Pollution levels in
China are comparably bad, but in China residential coal use is the
largest source, followed by residential use of biofuels (10).
Referring back to Figure 2, note that there are several aerosols
that cause cooling, in addition to black carbon that causes warming.
There are ongoing efforts to slow the growth of sulfur emissions or
reduce emissions absolutely, for the purpose of reducing acid rain. In
our alternative scenario for climate forcings, it is assumed that any
reduced sulfate cooling will be at least matched by reduced black
carbon heating. Principal opportunities in the West are for cleaner
more efficient diesel motors and cleaner more efficient coal burning at
utilities. Opportunities in the developing world include use of biogas
in place of solid fuels for household use, and eventually use of
electrical energy produced at central power plants.
Ozone (O3). Chemical emissions that lead to tropospheric
ozone formation are volatile organic compounds and nitrogen oxides
(carbon monoxide and methane also contribute). Primary sources of these
chemicals are transportation vehicles, power plants and industrial
processes.
High levels of ozone have adverse health and ecosystem effects.
Annual costs of the impacts on human health and crop productivity are
each estimated to be on the order of $10 billion per year in the United
States alone.
Ozone in the free troposphere can have a lifetime of weeks, and
thus tropospheric ozone is at least a hemispheric if not a global
problem. Emissions in Asia are projected to have a small effect on air
quality in the United States (11). Closer neighbors can have larger
effects, for example, recent ozone increases in Japan are thought to be
due in large part to combustion products from China, Korea and Japan
(12). A coordinated reduction of those chemical emissions that lead to
the formation of low level ozone would be beneficial to developing and
developed countries.
Our alternative scenario assumes that it will be possible, at
minimum, to stop further growth of tropospheric ozone. Recent evidence
suggests that tropospheric ozone is decreasing downwind of regions such
as Western Europe (13), where nitrogen oxide and carbon monoxide
emissions are now controlled, but increasing downwind of East Asia
(12). Global warming may aggravate summer time ozone production, but
this feedback effect would be reduced with the small warming in the
alternative scenario. The evidence suggests that cleaner energy sources
and improved combustion technology could achieve an overall ozone
reduction.
Methane (CH4). Methane today causes a climate forcing
half as large as that of CO2, if its indirect effects on
stratospheric H2O and tropospheric O3 are
included. The atmospheric lifetime of CH4 is moderate, only
8-10, years, so if its sources were reduced, the atmospheric amount
would decline rather quickly. Therefore it offers a great opportunity
for a greenhouse gas success story. It would be possible to stabilize
atmospheric CH4 by reducing the sources by about 10%, and
larger reductions could bring an absolute decrease of atmospheric
CH4 amount.
The primary natural source of methane is microbial decay of organic
matter under anoxic conditions in wetlands. Anthropogenic sources,
which in sum may be twice as great as the natural source, include rice
cultivation, domestic ruminants, bacterial decay in landfills and
sewage, leakage during the mining of fossil fuels, leakage from natural
gas pipelines, and biomass burning.
There are a number of actions that could be taken to reduce
CH4 emissions: (1) capture of methane in coal mining,
landfills, and waste management, (2) reduction of pipeline leakage,
especially from antiquated systems such as in the former Soviet Union,
(3) reduction of methane from ruminants and rice growing, as the
farmers' objectives are to produce meat, milk and power from the
animals, not methane, and food and fiber from the fields, not methane.
The economic benefits of such methane reductions are not so great
that they are likely to happen automatically. Methane reduction
probably requires international cooperation, including developing
countries. Although the task is nontrivial, it represents an
opportunity for a success story. In some sense, methane in climate
change is analogous to the role of methyl-chloroform in ozone
depletion. Although the growth of long-lived chlorofluorocarbons has
only begun to flatten out, stratospheric chlorine is already declining
in amount because of reductions in the sources of short-lived methyl-
chloroform.
6. alternative scenario: carbon dioxide
CO2 is the largest single human-made climate forcing
agent today, and its proportion of the total human-made climate forcing
can be anticipated to increase in the future. It is not practical to
stop the growth of atmospheric CO2 in the next several
decades. However, it is possible to slow the growth rate of CO2
emissions via actions that make good economic and strategic sense.
Scenarios for CO2 are commonly constructed by making
assumptions about population growth, standard of living increases, fuel
choices, and technology. This procedure yields a huge range of
possibilities with little guidance as to what is likely. An alternative
approach is to examine historical and current rates of change of
CO2 emissions, estimate the changes that are needed to keep
the climate change moderate, and consider actions that could produce
such rates of change. That is the procedure we explore here.
Fossil-fuel CO2 emissions. Figures 8 and 9 show U.S. and
global CO2 emissions. Emissions in the U.S. grew faster in
the 1800s than in the rest of the world, as the U.S. itself was still
growing and had rapid immigration. Growth of U.S. emissions was slower
than in the rest of the world during the second half of the 20th
century, when other parts of the world were industrializing.
The important period for the present discussion is the past 25
years, and the past decade. The U.S. growth rate was 1%/year over the
past 25 years, as we largely succeeded in decoupling economic and
energy use growth rates. The global growth rate was moderately higher,
1.4%, as there was faster growth in developing nations. However, in the
past decade the growth rate of U.S. CO2 emissions has been
higher than in the world as a whole (1%/year in the U.S. vs. 0.6%/year
in the world).
Figure 10 provides a useful summary. The U.S. portion of global
fossil fuel CO2 emissions increased from 10% in 1850 to 50%
in 1920. Since then the U.S. portion has declined to 23% as other parts
of the world industrialized. The temporary spike beginning in 1940 is
associated with World War II, including vigorous exertion of U.S.
industry to supply the war effort. In the 1990s the U.S. portion of
global emissions increased, despite oratory about possible climate
change and expectations that the developing world would be the source
of increasing emissions.
Growth rate required for ``alternative scenario''. A small change
in the CO2 emissions growth rate yields large changes in
emissions several decades in the future. A 1%/year growth yields a 64%
growth of emissions in 50 years, compared with constant emissions (0%/
year growth rate). A growth rate of -0.5%/year yields a -22% change of
emissions in 50 years. Thus CO2 emissions in 50 years are
more than twice as large in a 1%/year scenario than in a -0.5%/year
scenario.
Incomplete understanding of the Earth's ``carbon cycle'' creates
some uncertainty, but to a good approximation the increase in
atmospheric CO2 is commensurate with the CO2
emission rate. Therefore full achievement of the ``alternative
scenario'' probably requires the global CO2 emissions growth
rate to be approximately zero or slightly negative over the next 50
years.
Even if the United States achieves a zero or slightly negative
growth rate for CO2 emissions, there is no guarantee that
the rest of the world will follow suit. However, the economic and
strategic advantages of a more energy efficient economy are sufficient
to make this path attractive to most countries. It is likely that the
shape of the U.S. and global CO2 emissions curves will
continue to be fundamentally congruent. In any case, any strategy for
achieving a climate change ``soft landing'', whether pursued
unilaterally or otherwise, surely requires that the downward change in
the U.S. CO2 emission growth rates be at least comparable to
the change needed in the global average. There are many reasons for the
United States to aggressively pursue the technology needed to achieve
reduced CO2 emissions, including potential economic benefit
and reduced dependence on foreign energy sources.
It is not our task to suggest specific policies. However, we must
make the case that there are options for achieving the slower CO2
growth rate. Otherwise the alternative scenario is not viable.
In the short-term, a case can be made that pent-up slack in energy
efficiency (14), if pursued aggressively, can help achieve a zero or
slightly negative CO2 emissions growth rate. Renewable
energy sources, even though their output is relatively small, also can
contribute to slowing the growth rate of emissions. There has been
resistance of some industries to higher efficiency requirements. In
that regard, the experience with chlorofluorocarbons is worth noting.
Chemical manufacturers initially fought restrictions on CFC production,
but once they changed their position and aggressively pursued
alternatives they made more profits than ever. Similarly, if
substantially improved efficiencies are developed (for air
conditioners, appliances, etc.), such that there is a significant gap
between operating costs of installed infrastructure and available
technologies, that could facilitate increased turnover. Perhaps
government or utility actions to encourage turnover also might be
considered. Corporations will eventually reap large profits from clean
air technologies, energy efficiency, and alternative energies, so it is
important for our industry to establish a leadership position.
In the long-term, many energy analysts believe it is unlikely that
energy efficiency and alternative energy sources can long sustain a
global downtrend in CO2 emissions. Lovins (15) argues
otherwise, pointing out the cost competitiveness of efficient energy
end-use, gas-fired cogeneration and trigeneration at diverse scales,
wind power and other renewable sources. Certainly it makes sense to
give priority to extracting the full potential from efficiency and
renewable energy sources. Holdren (16) concludes that meeting the
energy challenge requires that we maximize the capabilities and
minimize the liabilities in the full array of energy options.
Many (my impression is, most) energy analysts believe that the
requirement of a flat-to-downward trend of CO2 emissions
probably would require increasing penetration of a major energy source
that produces little or no CO2. Our task is only to argue
that such possibilities exist. It will be up to the public, through
their representatives, to weigh their benefits and liabilities. We
mention three possibilities.
. Nuclear power: if its liabilities, including high cost and public
concern about safety, waste disposal and nuclear weapons proliferation,
can be overcome, it could provide a major no-CO2 energy
source. Advocates argue that a promising new generation of reactors is
on the verge of overcoming these obstacles (17). There does not seem to
be agreement on its potential cost competitiveness.
2. Clean coal: improved energy efficiency and better scrubbing of
particulate emissions present an argument for replacing old coal-fired
power plants with modern designs. However, CO2 emissions are
still high, so an increasing long-term role for coal depends on
development of the ``zero emissions'' plant, which involves CO2
capture and sequestration (18).
3. Others: Oppenheimer and Boyle (19) suggest that solar power,
which contributes very little of our power at present, could become a
significant contributor if it were used to generate hydrogen. The
hydrogen can be used to generate electricity in a fuel cell. Of course
the other energy sources can also be used to generate hydrogen.
In Holdren's (16) words: there are no silver bullets (in the array
of energy options) nor are there any that we can be confident that we
can do without. This suggests the need for balanced, increased public
and private investment in research and development, including
investments in generic technologies at the interface between energy
supply and end use (20). The conclusion relevant to the alternative
scenario is that, for the long-term, there are a number of
possibilities for energy sources that produce no CO2.
7. benchmarks
The alternative scenario sets a target (1 W/m2 added
climate forcing in 50 years) that is much more ambitious than IPCC
business-as-usual scenarios. Achievement of this scenario requires
halting the growth of non-CO2 climate forcings and slightly
declining CO2 emissions. Climate change is a long-term issue
and strategies surely must be adjusted as evidence accumulates and our
understanding improves. For that purpose it will be important to have
quantitative measures of the climate forcings.
Non-CO2 forcings. The reason commonly given for not
including O3 and soot aerosols in the discussions about
possible actions to slow climate change is the difficulty in
quantifying their amounts and sources. That is a weak argument. These
atmospheric constituents need to be measured in all countries for the
sake of human health. The principal benchmark for these constituents
would be their actual amounts. At the same time, we must develop
improved understanding of all the sources of these gases and aerosols,
which will help in devising the most cost-effective schemes for
reducing the climate forcings and the health impacts.
Methane, with an atmospheric lifetime of several years, presents a
case that is intermediate between short-lived air pollutants and
CO2. Measurements of atmospheric amount provide a means of
gauging overall progress toward halting its growth, but individual
sources must be identified better to allow optimum strategies. Improved
source identification is practical. In some cases quantification of
sources can be improved by regional atmospheric measurements in
conjunction with global tracer transport modeling.
Carbon Dioxide. Is it realistic to keep the CO2 growth
rate from exceeding that of today? The single most important benchmark
will be the annual change of CO2 emissions. The trend of
CO2 emissions by the United States is particularly important
for the reasons discussed above. Figure 11 shows the United States
record in the 1990s. The requirement to achieve the ``alternative
scenario'' for climate forcings is that these annual changes average
zero or slightly negative. It is apparent that, despite much rhetoric
about global warming in the 1990s, CO2 emissions grew at a
rate that, if continued, would be inconsistent with the alternative
scenario.
We suggest in the discussion above that it is realistic to aim for
a lower emission rate that is consistent with the alternative scenario.
This particular benchmark should receive much closer scrutiny than it
has heretofore. The climate simulations and rationale presented above
suggest that, if air pollution is controlled, the trend of this
CO2 benchmark, more than any other single quantity, can help
make the difference between large climate change and moderate climate
change.
8. communication
Our paper on the alternative scenario (1) was reported with a
variety of interpretations in the media. As I discuss in an open letter
(21), this may be unavoidable, as the media often have editorial
positions and put their own spin on news stories. Overall, the media
correctly conveyed the thrust of our perspective on climate change.
Furthermore, I suggest in my open letter that the Washington Post
editorial on our paper (23) represented an astute assessment of the
issues.
A basic problem is that we scientists have not informed the public
well about the nature of research. There is no fixed ``truth''
delivered by some body of ``experts''. Doubt and uncertainty are the
essential ingredient in science. They drive investigation and
hypotheses, leading to predictions. Observations are the judge.
Of course, some things are known with higher confidence than
others. Yet fundamental issues as well as details are continually
questioned. The possibility of finding a new interpretation of data,
which provides better insight into how something in nature works, is
what makes science exciting. A new interpretation must satisfy all the
data that the old theory fit, as well as make predictions that can be
checked.
For example, the fact that the Earth has warmed in the past century
is well established, and there is a high degree of confidence that
humans have been a major contributor to this warming. However, there
are substantial uncertainties about the contributions of different
forcings and how these will change in the future.
In my open letter (21) I note the potential educational value of
keeping an annual public scorecard of measured changes of (1) fossil
fuel CO2 emissions, (2) atmospheric CO2 amount,
(3) human-made climate forcing, and (4) global temperature. These are
well-defined quantities with hypothesized relationships. It is possible
to make the science understandable, and it may aid the discussions that
will need to occur as years and decades pass. It may help us scientists
too.
9. summary: a brighter future
The ``business-as-usual'' scenarios for future climate change
provide a useful warning of possible global climate change, if human-
made climate forcings increase more and more rapidly. I assert not only
that a climatically brighter path is feasible, but that it is
achievable via actions that make good sense for other reasons (22, 24).
The alternative scenario that we have presented does not include a
detailed strategic plan for dealing with global warming. However, it
does represent the outline of a strategy, and we have argued that its
elements are feasible.
It is impractical to stop CO2 from increasing in the
near term, as fossil fuels are the engine of the global economy.
However, the decline of the growth rate of CO2 emissions
from 4 to 1%/year suggests that further reduction to constant emissions
is feasible, especially since countries such as the United States have
made only modest efforts at conservation. The potential economic and
strategic gains from reduced energy imports themselves warrant the
required efforts in energy conservation and development of alternative
energy sources. It is worth noting that global CO2 emissions
declined in 1998 and again in 1999, and I anticipate that the 2000 data
will show a further decline. Although this trend may not be durable, it
is consistent with the alternative scenario.
The other requirement in our alternative scenario is to stop the
growth of non-CO2 forcings, which means, primarily, air
pollution and methane. The required actions make practical sense, but
they will not happen automatically and defining the optimum approach
requires research.
A strategic advantage of halting the growth of non-CO2
forcings is that it will make it practical to stop the growth of
climate forcings entirely, in the event that climate change approaches
unacceptable levels. The rationale for that claim is that an ever-
growing fraction of energy use is in the form of clean electrical
energy distributed by electrical grids. If improved energy efficiency
and non-fossil energy sources prove inadequate to slow climate change,
we may choose to capture CO2 at power plants for
sequestration.
Global warming is a long-term problem. Strategies will need to be
adjusted as we go along. However, it is important to start now with
common-sense economically sound steps that slow emissions of greenhouse
gases, including CO2, and air pollution. Early emphasis on
air pollution has multiple immediate benefits, including the potential
to unite interests of developed and developing countries. Barriers to
energy efficiency need to be removed. Research and development of
alternative energies should be supported, including a hard look at next
generation nuclear power. Ultimately strategic decisions rest with the
public and their representatives, but for that reason we need to make
the science and alternative scenarios clearer.
references
. Hansen, J., M. Sato, R. Ruedy, A. Lacis and V. Oinas, Global
warming in the twenty-first century: an alternative scenario, Proc.
Natl. Acad. Sci., 97, 9875-9880, 2000.
2. Intergovernmental Panel on Climate Change, Climate Change 1995,
J.T. Houghton, L.G. Meira Filho, B.A. Callandar, N Harris, A.
Kattenberg and K. Maskell (eds.), Cambridge Univ. Press, Cambridge,
England, 572 pp., 1996; Intergovernmental Panel on Climate Change,
Climate Change 2000, editors . . . 2001.
3. Hansen, J., R. Ruedy, A. Lacis, M. Sato, L. Nazarenko, N.
Tausnev, I. Tegen and D. Koch, in General Circulation Model
Development, ed. D. Randall, Academic Press, New York, pp. 127-164,
2000.
4. Hoffert M.I. and C.Covey, Deriving global climate sensitivity
from paleoclimate reconstructions, Nature, 360, 573-576, 1992.
5. Hansen, J., A. Lacis, D. Rind, G. Russell, P. Stone, I. Fung, R.
Ruedy and J. Lerner, Climate sensitivity: analysis of feedback
mechanisms, Geophys. Mono., 29, 130-163, 1984.
6. Hansen, J. et al., Climate forcings in the GISS SI2000 model, to
be submitted to J. Geophys. Res., 2001.
7. Levitus, S., J.I. Antonov, T.P. Boyer and C. Stephens, Warming
of the world ocean, Science, 287, 2225-2229, 2000.
8. Kunzil, N., R. Kaiser, S. Medina, M. Studnicka, O. Chanel, P.
Filliger, M. Herry, F. Horak, V. Puybonnieux-Texier, P. Quenel, J.
Schneider, R. Seethaler, J.C. Vergnaud and H. Sommer, Public health
impact of outdoor and traffic-related air pollution: a European
assessment, The Lancet, 356, 795-801, 2000.
9. Smith, K.R., National burden of disease in India from indoor air
pollution, Proc. Natl. Acad. Sci., 97, 13286-13293, 2000.
0. Streets, D.G., S. Gupta, S.T. Waldhoff, M.Q. Wang, T.C. Bond and
B. Yiyun, Black carbon emissions in China, Atmos. Envir., in press,
2001.
1. Jacob, D.J., J.A. Logan and P.P. Murti, Effect of rising Asian
emissions on surface ozone in the United States, Geophys. Res. Lett.,
26, 2175-2178, 1999.
2. Lee, S.H., H. Akimoto, H. Nakane, S. Kurnosenko and Y. Kinjo,
Lower tropospheric ozone trend observed in 1989-1998 at Okinawa, Japan,
Geophys. Res. Lett., 25, 1637-1640, 1998.
3. Simmonds, P.G., S. Seuring, G. Nickless and R.G. Derwent,
Segregation and interpretation of ozone and carbon monoxide
measurements by air mass origin at the TOR station Mace Head, Ireland
from 1987 to1995, J. Atmos. Chem., 28, 45-59, 1997.
4. Brown, M.A., The role of CO2 gases in climate policy,
workshop of United States Association for Energy Economics, Washington,
DC, October 16, 2000.
5. Lovins, A.B. and L. Hunter Lovins, Climate: Making Sense and
Making Money, Rocky Mountain Institute, Snowmass, CO, http://
www.rmi.org/images/other/C-/ClimateMSMM.pdf; Hawken, P.G., A.B. Lovins
and L.H. Lovins, Natural Capitalism, Little Brown, NY, 1997,
www.natcap.org.
6. Holdren, J.P., Meeting the energy challenge, Science, 291, 945,
2001.
7. Wald, M.L., Industry gives nuclear power a second look, New York
Times, April 24, 2001.
8. Ecoal, Harnessing energy with reduced emissions to atmosphere--
the pace of research to generate dynamic solutions for coal, World Coal
Institute Newsletter, 36, December, 2000; also see Williams, R.H.,
presentation at symposium at Nuclear Control Institute, Washington, DC,
April 9, 2001..
9. Oppenheimer, M. and R.H. Boyle, Dead Heat, Basic Books, New
York, 1990.
20. Nakicenovic, N., A. Grubler and A. McDonald, Global Energy
Perspectives, Cambridge Univ. Press, Cambridge, U.K., 1998.
21. Hansen, J., An open letter on global warming, http://
naturalscience.com/ns/letters/ns--let25.html.
22. Hansen, J., A brighter future, Clim. Change, in press, 2001.
23. Anonymous, Hot news on global warming, Washington Post, page
A18, August 28, 2000.
24. Hansen, J., Try a common-sense response to global warming,
International Herald Tribune, Nov. 16, 2000.
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The Chairman. Thank you, Dr. Hansen. I want to thank all
the witnesses for being here. Dr. Lindzen, you said we need to
support science without promoting alarmism. How do you do that,
and if you would speak close to the mike.
Dr. Lindzen. A good question. It seems to me that to some
extent that will require more trust of the scientific
community. Essentially, in the post war period you typically
had from the Armed Forces 5-year grants covering significant
numbers of scientists, minimal paperwork, and so on.
This was a very productive period for science. As you ask
for more direct evidence of relevance, the easiest form of
relevance becomes alarm, and you encourage a kind of bad trend.
I do not have an easy answer to it, but I think it is something
that should be thought out. You do not want bias built into
your scientific support system.
The Chairman. Thank you. It is my understanding that all
five members of the panel have been involved in the IPCC
report. Dr. Lindzen said that hundreds of scientists were never
asked, that the report was changed in Shanghai, and that
significant pressure was exerted. I would like to hear the
other four witnesses' response to those rather serious
statements.
Dr. Ramaswamy, we will begin with you, sir.
Dr. Ramaswamy. I think--and this is going to be a long-
winded answer, but the transfer of what is in the detailed
technical chapter report, the transfer of that information to
the summary for policymakers admittedly involves lots of
careful choices of words and sentences and phrases, because it
has to be a short summary, and so doubtless, you know, some of
the information that is in the chapters will not appear in the
summary.
But I must say I was there in Shanghai. I was there in the
plenary, and I believe there were lead authors from--I have not
checked carefully, but I think the lead authors from all the
chapters were present at the meeting in Shanghai. The way the
deliberations went concerning the summary for policymakers:
First of all, the draft was drawn up by scientists; any changes
that were to be introduced in Shanghai--if changes were to be
introduced, it was only in response to some comments.
If some reviewer had comments, or someone on the floor had
some comments, then there were considerations of how the words
had been crafted, how the sentence had been crafted, and after
that the scientists had to agree, basically, on any language
that went in.
If the scientists objected, that language never made its
appearance, and so I believe that scientists did contribute
significantly to the sense expressed in the summary for
policymakers. Admittedly not all the scientists were involved
in the drafting process of the chapters there, but by and large
there was a representation from, I believe, all the chapters
there, so this was pretty important, because these scientists--
--
The Chairman. Was there pressure exerted to change the
report?
Dr. Ramaswamy. No, there was no pressure exerted as far as
I know. I was there on the floor on all the days, and there was
no pressure exerted. In fact, there were moments when language
that somebody would insist on was totally vetoed by the
scientists, and that was the final word. Because the scientists
did not like it that wording did not go in. Having said that, I
would think it is true to say that not everything that is in
the chapters did come through in the summary for policymakers,
but these were by and large what I would call details with
respect to certainties or uncertainties, not the major points.
So for example, Dr. Lindzen mentioned the uncertainty we
have about water vapor and clouds and climate feedbacks, and
that is a very prominent uncertainty, and that was recognized
in the summary for policymakers.
So as I said at the outset, there is a problem in trying to
use the English language to condense 1,000 pages down to 15 or
20 pages, but I do not believe that the principal findings were
in any way muted in the transfer from the chapters to the
summary.
The Chairman. Dr. Sathaye.
Dr. Sathaye. Yes, thank you, Mr. Chairman. I think it might
be worth explaining very briefly the process we go through in
order to arrive at the Summary for Policymakers. Each of the
chapters has an Executive Summary that is prepared with full
participation of all the authors who have worked on that
chapter. That Executive Summary is then used to produce two
documents. One is the Technical Summary and the other is the
Summary for Policymakers, and they have different audiences.
You do not necessarily want all of the technical material
we put in the Technical Summary to appear in the Summary for
Policymakers, which is intended for a completely different
audience. We often have a lot more material in the Technical
Summary which need not appear in the Summary for Policymakers,
and this certainly was the case with the Working Group III
report.
The Chairman. I understand that, doctor, but my question
was, were hundreds of scientists never asked and was it changed
in Shanghai? Was there pressure brought to bear on those who
were drafting the report?
Dr. Sathaye. I worked on the Working Group III Report,
which did not meet in Shanghai, but the process was very
similar, and at no point in time was there pressure brought on
any of the authors to change any of their findings. Indeed, as
Ram just mentioned, in Akra, delegates consulted us. They made
sure that the language we were using was accurate, and we made
changes to that language to make sure that it fully reflected
the underlying report.
The Chairman. Thank you.
Dr. McCarthy.
Dr. McCarthy. Thank you. I would just echo the comments of
my two colleagues. I was in Shanghai, the working group that I
chair had its final plenary meeting in Geneva. The process that
was just described was the same for Working Group 2. The actual
drafting of the Summary for Policymakers (SPM) was done by
about 60 authors, but every author had an opportunity to see
each draft as it was initially prepared before a meeting of all
authors last August. Everyone had a chance to look at the
responses to the government reviews and every author had an
opportunity to see the revisions to the SPM.
We took the revised form of the SPM to our plenary meeting
in Geneva, and I would describe the process as one of trying to
take, as mentioned by my colleagues, a document that is full of
the representation of scientific detail first to a summary
document, the Technical Summary, and then to as clear a
statement as scientists can produce--that is, strip all the
jargon, to make the language of the Summary for Policymakers
intelligible to anyone who would care to know how this
information might be used in a policy context. So I see the
plenary, really, as the final clarifying process.
Now, similarly, we had about 40 of our authors--that is,
our lead authors of every chapter present at that final
meeting. If at any time a question was made, or raised from the
floor of the plenary, by any of the 150 delegates from 100
nations, about a particular statement, saying for example, that
they thought it should be worded differently, if the suggested
change was simply for the purpose of clarifying the language,
and the authors present concurred that the proposed change did
not alter the scientific meaning, then the suggestion would
stand.
At times a suggestion by a delegate from one country would
be opposed by another saying no, I do not think that makes it
clearer at all, so a lot of our discussion went back and forth
involving maybe a third delegate, who came up with yet another
suggestion, and if we got stuck in a situation like this, then
the chair would ask a small group to retire during lunch and
have a smaller meeting, open to everyone, but asking someone to
chair it, and then to come back to the full plenary with a
proposed solution.
So literally, the process is one in which we never vote. We
would proceed through the document until at the end of the day
all delegations say, I am satisfied I fully understand this
document, it is gaveled, and it is then fully accepted by the
plenary.
The Chairman. Dr. Hansen.
Dr. Hansen. That is a very difficult question. The IPCC is
carrying out a very necessary process, and the technical work
is superb. It involves a large number of outstanding
scientists, and I am in no way critical of those scientists,
but I must say I have a significant degree of discomfort with
the extrapolation of the science into policy directions, the
close interconnection of the IPCC and the Kyoto discussions.
I also think that a large committee is seldom the best
approach for determining actions. I do not feel that I have a
prescription or that I know the best procedure to do this, but
I felt much more comfortable with the assessment 20 years ago
when it was done by the National Academy of Sciences, a stellar
committee chaired by Joel Charney of MIT, who stayed away from
policy but gave an outstanding scientific assessment.
So I do not have a very good answer to that, but I feel
some discomfort about it.
The Chairman. Thank you. I would like to ask one more
question of the panel, and this is something which I am sure
will not be an easy one or a comfortable one for you to respond
to. I want you to for a moment put yourself in the shoes of the
legislator. We have now received numerous reports. We now have
cumulative evidence that there is climate change. We have had
some disagreements on what should be done, if anything, and so
I would like to begin with you, Dr. Lindzen, and ask you, as a
legislator, what policies or what legislation would you propose
to attempt to address these issues, if any? Perhaps none.
Dr. Lindzen. I think it may be premature to take actions
explicitly designed for this. I think there is general
agreement with taking care of things like efficiency, reduced
toxic pollution and so on, which have independent benefits.
This is, I think, what is referred to as no regrets. I think
with respect to science, treat it as an open question and ask
that the physics be improved.
At present, I mean, it is a point I make in my testimony,
it is widely understood that doubling CO2 alone
gives you about a degree centigrade warming. The rest of the
higher predictions come from the so-called feedback processes.
These are very weakly understood. They are crucial, and they
are in many ways not the focus of our research. I think they
deserve more.
The Chairman. Dr. Ram.
Dr. Ramaswamy. Well, that is a difficult question, and I
guess I am going to stick to my parochial barriers here and
essentially emphasize--in fact, I would reiterate Dr. Lindzen's
point, that good, sound science should be the underpinning for
any policy decision, and the science should be checked and
rechecked constantly, because science is an evolving thing. It
is advancing all the time.
So there should be a careful scrutiny of the science, and I
would emphasize that besides the measurements we also need
process studies and modeling to go along with it. The three
actually go simultaneously together.
You cannot have a decision based on just observations. You
cannot have a decision just based on models alone, and I think
it is this collective picture, looking at all the observations
and indicators, coupled with model simulations, and coupled
with the understanding of the physical processes, that
essentially unites and completes the picture. If you had just
one of them, that is not the whole picture, so I would
emphasize that that be the underpinning for the policy
decisions.
I know this is not the direct answer to your question, but
it is kind of in a roundabout way.
The Chairman. Dr. Sathaye.
Dr. Sathaye. Well, never having been a legislator, this is
a tough question to answer, but since the work that I do
focuses a lot on technologies and costs and policies, let me
just suggest a few areas which are, as others have mentioned
before me, worth pursuing regardless. It is very clear that
energy efficiency improvements and long-term R&D would form the
backbone of any decisions you might make, if not today, perhaps
some years from now, and in fact the question about how soon do
you wish to act, or one should act, depends a lot upon what
levels you wish to stabilize climate at, for which we do not
have a consensus.
If you want to stabilize at 450, you need to start reducing
emissions by 2015, and so forth, and so without having that
particular consensus, one pursues other things that are good
for the economy, and I do not think we are doing nearly enough
in that area.
The Chairman. Do you not think that there is largely an
emerging consensus on this issue?
Dr. Sathaye. Yes, there is an emerging consensus on this
issue. The sooner there is consensus, or the lower your
emissions are, the sooner you will act; the more room you will
have to play later on, so to speak.
The Chairman. Dr. McCarthy.
Dr. McCarthy. Thank you, Mr. Chairman.
The Chairman. By the way, I am aware this is a very
difficult question and I ask it of myself every day.
Dr. McCarthy. Some of us took the easy route and retired to
an academic life, rather than the difficult route, that of a
legislator.
I think that there are several things we can and should do
right away. I think some of these suggestions have been made
already by my colleagues taking the lead from Dr. Hansen on no-
regrets policies.
I think the notion that there may be some low-hanging fruit
with some of the other greenhouse gases should be explored
vigorously, but I do believe that this is an issue that we
should look at very differently today than just 5 or even 10
years ago, because as the Summary for Policymakers in this
third assessment says for the impacts of climate change, we
know now about impacts, things we did not know 5 years ago
because of the recent rate of some of these changes.
With respect to the comments made by Senator Stevens, I
would comment that one of my hobbies is the old polar
exploration literature. It would be fair to say if someone had
told me 5 years ago that we would be seeing within the next 10,
20, 30 years the opportunity for ships to travel through the
Northwest Passage, I would have said that is inconceivable.
Historically, this name has been a misnomer. It should have
been called the Northwest impediment.
The fact that we have seen these dramatic changes, and they
are entirely consistent, as I have said, where we have examined
thousands of papers, and for 80 percent of them, these changes
are consistent with the local changes in temperature. This
tells us that responses to climate change are occurring more
quickly than we had thought possible.
Now, I know Dr. Lindzen said we do not understand the
physics, and I certainly do not understand the physics, but
Working Group 1 tells us that intense heat spells, intense
precipitation events, increased wind velocities associated with
tropical storms, and increased El Nino like conditions are all
projections for future climate with 90 percent confidence.
Now, I am not an expert on that. I cannot possibly explain
the mechanism, but that is part of the summary statement from
the Working Group 1 report. If we are wrong and find that these
factors are not so serious, then we could feel comfort in
having sat aside and waiting for clearer signals. But if we are
wrong in the other direction and if they are even more serious
than we think they are, then these consequences could be even
larger.
I think an appropriate way to look at this is rather like
insurance, the insurance that we invest in for all of our
personal property, and our lives. I think that to gamble that
these projections will not be borne out within the near future
is a very, very risky step, and I believe, as our report says
very clearly, that even the most aggressive actions that have
been proposed will not prevent some of this damage. In addition
to looking very seriously at all mitigation options, we must
look very seriously at enhancing opportunities for adaptation,
not only in those regions that are going to be most hard-hit,
the tropic and subtropical regions, but also in northern
industrialized countries as well.
The Chairman. Dr. Hansen.
Dr. Hansen. I agree that first of all we should take the
steps that have other benefits and, in fact, I think these may
take us most of the way and perhaps all of the way to what we
need. I refer particularly to pollution, the examples I gave
with regard to air pollution. Also, we need to support energy
efficiency and alternative energies, because of the strategic
value they will have with regard to our energy independence.
Second, we should make the measurements that are necessary so
we can understand what is really happening to the climate
system. Third, we need to adapt the approach as we go along.
This is a long-term issue.
The Chairman. Thank you. There is a vote on. Senator
Brownback is over voting, and he will be back for his
questions. I am going to go vote and will be back. Senator
Kerry, do you want to start?
Senator Kerry. Is Senator Brownback going to come back?
The Chairman. Yes, or I can recess.
Senator Kerry. Why don't we recess, and I will come back,
too.
The Chairman. We will take a brief recess. Senator Kerry
and Senator Brownback will come back. Senator Kerry will have
questions as soon as he returns. He is very quick.
[Recess.]
Senator Brownback. If we could bring the committee back to
order, sorry about the brief intermission. We have a vote on on
the floor, and we will continue with the hearing, if you do not
mind. Let me make a couple of comments, if I could to you, and
ask that my full opening statement be put into the record, at
the appropriate place in the record. I appreciate the testimony
you gentlemen have given and the information you have put
forward.
I have put forward two bills that I think are in lines with
the keeping of some of the items that you have suggested, and I
just want to draw your attention to it and then ask your
comments about it. Number 1 is a domestic carbon bill that
would make small payments to farmers, primarily, on the basis
of practices that they would use that would increase CO2
or carbon sequestration in the soil.
These I think would be generally practices along the lines
of a no-regrets policy, as one of you had identified that would
approve soil conservation, soil quality by putting back into
the soil carbon, which has been released when we tilled up the
prairies, when we have gone to plowing previously, and this
would be coming back to more of a no-till, more fixing the
carbon into the soil, so that you would reward farmers for a
process of farming, not necessarily production of farming, but
a process by which they would farm that would fix more carbon
in the soil, and these would be the practices that would be
agreed to by appropriate scientific and USDA models and panels.
The second item is a bill that provides for $200 million in
tax credits to individuals or companies in the United States
that invest in reforestation, either domestic or abroad. This
is modeled after what I think is a start of a pretty
successful-looking project by the Nature Conservancy in South
America. They have got projects going in Belize, Bolivia, and
Brazil. I am hoping they will get outside of just B countries
and into all nations.
I toured one in January in Brazil, where they had bought
back about 150,000 acres in the Atlantic forest region in
Brazil that had been broken out, farmed, and then had returned
to pasture for water buffalo, and they were buying it back to
turn it back to Atlantic forest region. They were measuring the
amount of carbon that was being fixed over a 40-year cycle,
working with the local nongovernmental organization in Brazil
that actually owned the land. The money was put up by groups in
the United States, several large companies that put the
resources up to actually purchase the property.
What I would do is provide tax credits, about $200 million
initially, to try to incentivize and encourage more of these
reforestation carbon-fixing, or carbon sinks, as I have
addressed it in both types of models.
I would be curious what you think about these sort of
incentivized--and I would like to think along the lines in the
future, sa we reduce CO2, that we will do so on a
market basis, where we do it on a least-cost type of models,
that these would be kind of early types of models where you get
the low-lying fruit of pretty quick CO2 sinks,
sequestrations that would take place with these.
Any thoughts about models like this from any of the
panelists, or if you yourself have thought along any of these
policy models?
Dr. Sathaye.
Dr. Sathaye. Yes, I think--let me speak with a personal--
from a scientific perspective on this topic. We had an IPCC
report on forestry that looked at many of the questions related
to project-specific soil conservation. I think at the outset I
should say yes, it is a great idea, and that it is worth
pursuing.
Certainly land exchange and forestry options offer an
important sink for carbon, and the no-till agriculture you
mentioned would be one of the types of activities that could be
done in the United States and in other countries as well.
Indeed, in many cases these types of projects have the
potential to bring in early monetary returns for the investor.
As the trees grow, and if you are in a position to sell
that carbon, you can get revenues fairly early on, and it is a
good thing for these types of projects.
There are two issues, though, that one needs to be careful
about in pursuing these projects. One has to do with a question
of permanence, and this, too, has been alluded to by many. One
of the challenges is, how long would these carbon sinks last?
We lose carbon at some point in time. We have four different
ways of dealing with that, and to the extent that these
projects incorporate one of those four ways, then you can,
indeed, pursue these kinds of projects.
The four ways are, they all amount really to accounting for
any carbon that you lose and this may be done through an
insurance scheme, it may be done by simply starting another
project in place of whatever carbon you might lose, so there
are different approaches to it. Well, we know how to deal with
it.
The second issue has to deal with what is being labeled as
leakage, and this is where, if you practice, let us say,
reducing deforestation in a given area, and if they go to some
other place and start deforesting, then you lose any carbon
benefits you might get in the area that you stopped the
deforestation from. How do you avoid that?
Here, too, we have ways to address leakage by pursuing
multicomponent projects. You have wide deforestation in one
area, then you can provide incentives in another area, so we
have ways of dealing with this, and to the extent we take care
of those, these are as good an approach for removing carbon out
of the atmosphere as we might get out of energy efficiency, or
alternative energy sources.
Senator Brownback. Others? Dr. Hansen, did you have any
thoughts on this, perchance?
Dr. Hansen. Well, on the face of it they are both
commendable activities. It does depend upon the kind of detail
we were just hearing about, and I think it is important to
quantify the degree to which these other benefits in addition
to reducing CO2 in the air, are in fact realized. We
need to have a good cost-benefit analysis. Even though I am
from Iowa, I do not claim to have expertise on exactly what the
impact will be, of either the no-till or the reforestation,
because of these possible indirect effects. So I cannot really
say much now that can help you.
Senator Brownback. Dr. McCarthy.
Dr. McCarthy. Just briefly, Senator Brownback, I, too,
believe that this is an example of the sort of incentive the
government can provide that could in some instances make a
substantial difference.
It has, however, only been within the last, maybe handful
of years that scientists have begun to look rather rigorously
at some of these balances and the effects of perturbations, and
the cessation of a perturbation on an ecosystem, but it is very
clear that that is an area that has potential to be an
important contributor, and I would just add that it is also
important to keep in mind--I am not directing this to you
personally, but to all of us, that there is no single best way
to address the sort of larger question we are asking, and I
think this is an example of mitigation options that people
would not have thought of a decade ago as having any potential.
Within the last 5 years we have begun to look at it
carefully. It appears now that with the sort of qualifications
my colleagues have mentioned, that it does have potential and
should be looked at very carefully.
Senator Brownback. Dr. Sathaye, is this the sort of thing
that could possibly be used in emissions trading? You talk
somewhat about emissions trading, and least-cost approaches for
CO2 reductions. Would you, particularly on
reforestation efforts, support the use of that on an emissions
trading type of basis?
Dr. Sathaye. First of all, yes, you could include
reforestation options in the emissions trading scheme but the
way it is being discussed, and the way it has been talked
about, is to have reforestation projects in other countries,
and then trade--let us say you do a reforestation project in
Europe some place, or Asia, the carbon that you sequester
through that process could be traded with carbon needs here.
That is certainly a legitimate way of doing it, and it
could be identical, to what you would get from any other type
of energy source.
A couple of caveats that I mentioned earlier about
permanence, and also this question of how carefully can you
measure carbon. We have carbon in four different pools. In the
forestry projects, we have it in vegetation, in soils, in
products, and in above and below-ground vegetation, litter and
so forth. These are the pools.
Senator Brownback. Those are being measured in the Bolivia
and the Brazilian project pretty aggressively, and I do not
know if the scientific community has agreed to the measurement
method that they want to go with, but they are measured on a
first year, third year, and then every fifth year, then on
through 40 years to try to address a permanence issue, and
leakage issue is also addressed in the bill, requiring to work
with local people to encourage them to be able to stay, but
shift their economic income sources from what they have been in
the past.
Dr. Sathaye. There is no difficulty in measurement methods.
We know how to measure carbon. If somebody brought it to my lab
and said, ``measure this carbon, from this soil,'' or ``we can
do it.'' The challenge is really whether we have a system set
up in order to do these kinds of measurements on a normal
basis, and how much might this cost.
Senator Brownback. The final question I want to ask, Dr.
Hansen, you mentioned something about a clean coal type of
technology, and I think this is also in another testimony,
where you actually capture the CO2 at the end of the
pipe, I guess, and store it, is that correct?
Dr. Hansen. Yes. The danger with coal is that it is by far
the largest potential source of atmospheric CO2,
with about 10 times as much as oil and gas. So you have to be
very careful about introducing greater coal use. We can reduce
the black carbon probably fairly easily, that is the soot, with
more efficient burning and filters on the smokestacks. In fact,
that would do some good, but if we then start burning so much
coal that we are producing more and more CO2, that
would be counterproductive. So it is, I think, important to
explore this possibility of zero emissions coal, but again I am
not an expert on that.
I have heard that Germany, Japan, the United States, all
are working toward that type of technology, and there have been
some impressive presentations about that. It really needs to be
looked at, because if that were possible----
Senator Brownback. That solves a lot of our problems.
Dr. Hansen. It does solve a lot of our problems, but it is
bound to increase the cost of coal use, so is China going to
take that extra step to capture CO2? They have a lot
of coal.
So it is an open issue. I think it really needs to be
looked at pretty hard.
Senator Brownback. I just noted that in your testimony.
That is very interesting. I was not familiar with how you would
do that, but apparently that is being researched and looked at
now. That is not known as a real solution.
I am sorry, I am going to have to slip on here, and I do
not know that--I understand Senator Kerry is supposed to be
coming back. Let me just say, if I could, in conclusion--and
maybe he will come back in the interim here--is that a number
of us are going to be working on ways that we can move forward
on some no-regrets policies, items that have multiplicity of
benefits you are talking about.
In addition to reducing CO2, or in recapturing
CO2, there would be positive effects, and I think
that in the state of play where we are as a nation and as
policymakers at this point in time, that that is probably the
best route to go, and I hear several of you suggesting that
indeed is the route that you would suggest that we proceed. I
hope you would engage us on a very open basis to suggest and to
help us work through those so that we can start to address this
issue that has been building for a long period of time that
needs to be addressed.
There is still some cautiousness on some parts, but I think
we can do things that at the end of the day we would say, there
is no real reason why we should not do these steps.
I want to thank you all very much. We are going to stay in
recess until Senator Kerry returns. If the panel does not mind
for a few minutes we will be in recess.
[Recess.]
Senator Brownback. I call the hearing back to order. Let me
apologize to our panelists. I have been told that Senator Kerry
will not be returning.
I do want to thank the panels and those that have been
watching, and in attendance. I note there will be a
subcommittee hearing on solutions, and these no-threat types of
proposals, and we will be holding that within the next couple
of weeks as we start to work through some plausible legislative
solutions we can proceed with. The record will remain open for
the requisite number of days for additional testimony to be
submitted, or questions to be submitted. I thank the panelists
again for being in attendance and sharing their views with us.
The hearing is adjourned.
[Whereupon, at 11:30 a.m., the committee adjourned.]
A P P E N D I X
Prepared Statement of Hon. John F. Kerry, U.S. Senator
from Massachussetts
I want to thank Chairman McCain for holding today's hearing. As I
have expressed to the Committee before, I believe that addressing the
threat of climate change is one of the great challenges before the
nation and the world. It certainly deserves the attention of this
Committee.
Our topic today is the Intergovernmental Panel on Climate Change's
Third Assessment Report. I want to take just a moment to discuss some
of the history of the IPCC.
The Panel was created in 1988 to serve as an independent advisor to
world leaders in assessing the scientific, technical and socio-economic
information relevant for the understanding of the risk of human-induced
climate change. Here in Washington that translated into studying the
``scientific uncertainties'' of global warming.
In an April 1989 appropriations letter to Congress, President Bush
wrote, ``Significant uncertainties remain about the magnitude, timing,
and regional impacts of global climate change. During Fiscal Year 1988,
the United States has made major contributions to international plans
to reduce those uncertainties.'' Among the contributions the President
noted was the Intergovernmental Panel on Climate Change, which, he
said, ``launched its multilateral effort in November 1988 with U.S.
participation and support.''
In a speech to the IPCC in February 1990, President Bush concluded
that ``human activities are changing the atmosphere in unexpected and
unprecedented ways.'' And that, ``the United States will continue its
efforts to improve our understanding of climate change, to seek hard
data, accurate models and new ways to improve the science and determine
how best to meet these tremendous challenges.''
I think the fundamental question before this Committee today is,
``What have we learned in 10 years of study and three assessment
reports from the IPCC?'' My sense is the Panel has fulfilled its
mission as an independent, scientific adviser to the nations of the
world. It is also my sense that the Committee can place great
confidence in the notion that human activities are contributing to
rising atmospheric concentrations of greenhouse gases with potentially
adverse consequences for the environment and millions of people.
Uncertainty exists--as it does in almost all matters of public
policy--but that uncertainty has been reduced significantly over the
past decade. And some uncertainty does not always justify inaction. In
1989, Secretary of State James Baker III spoke to the IPCC. He stated
that, ``[W]e can probably not afford to wait until all the
uncertainties have been resolved before we do act. Time will not make
this problem go away.'' I agree with Secretary Baker.
Unfortunately too many individuals, companies, nations and some in
the Congress have used the fact that we can never be absolutely certain
of how a natural system as complex as the global climate will respond
to confuse the debate and undermine any meaningful policies.
That is why 10 years since Secretary Baker made that statement and
despite more conclusive science, our nation has done so little to
resolve the threat of climate change. Our emissions--despite our pledge
to cut them in the Framework Convention on Climate Change have only
grown. I hope Mr. Chairman, that this hearing will help build a
foundation for the Congress to move constructively toward lowering our
greenhouse gas emissions and responding to the threat of climate
change.
In closing, Mr. Chairman, I want to express my disappointment in
those who now attack the IPCC because they do not like its scientific
conclusions. They assail the process of the IPCC and the motives of
individuals who have lead the IPCC effort. Dr. Lindzen and my
colleagues Senators Craig and Hagel have submitted such testimony
today. I have listened carefully to their comments--and I respectfully
disagree. I believe the scientists involved in the IPCC have done their
best to provide an independent and honest assessment of the state of
knowledge of the world's climate. It is an extraordinary charge we have
given them, and I do not question their tremendous effort.
I thank the IPCC for its work. I thank our panelists for joining us
today. And I thank the Chairman for holding this hearing.
______
Responses to Written Questions Submitted by Hon. John McCain
to Dr. Venkatachala Ramaswamy
Question 1. The IPCC report states that climate models have evolved
and improved significantly since the last assessment. However, the
National Research Council reports indicates that US modeling
capabilities trails those of Europe. Do you agree with that assessment?
I would like to first thank the Committee for the invitation to
appear, and to present my testimony on climate change science. I am
very appreciative of the thoughtful questions that have been put
forward as follow-up to the testimony. In my testimony, as requested, I
focussed exclusively on the scientific evaluations, following the
details spelt out in the IPCC 2001 assessment. Partly because of the
nature of the follow-up questions, I find that I have to go beyond the
scope of the IPCC report, and include personal views in response to
some of the questions.
Answer. On the first element under this question, coupled
atmosphere-ocean climate models have evolved and improved significantly
since the time of the previous IPCC assessment (IPCC, 1996). There is
now improved knowledge of the physics based on theoretical and
observational developments, including a longer observational record.
For example, there is now an improved understanding of convection,
radiation, boundary layer, and clouds, which constitute key climate
feedback processes. These improvements have led to better
representations of the physical processes in models and, therefore,
increased credibility of the models to perform simulations of climate
variations and change. There are now better simulations of climate, at
least down to continental scales and over temporal scales from seasonal
to decadal, including slight improvements in simulating El Nino.
Confidence in model projections has also increased owing to the ability
of climate models to maintain stable, multi-century simulations of
climate; these are of sufficient quality for use in addressing climate
change questions. Confidence in the ability of models to project future
climates has been enhanced by the ability of several models to
reproduce the warming trends in the 20th century surface temperature
when driven by the known natural and anthropogenic forcings. Systematic
intercomparisons of coupled climate models developed in recent years
provides another line of evidence for the growing capabilities of such
tools. Although there remain key uncertainties and quantitative aspects
of key climate processes have yet to become robust, important
scientific strides have been made in coupled atmosphere-ocean modeling
since the last assessment.
The second part of the question touches upon a somewhat different
issue viz., ``US versus Europe's modeling capabilities''. There are
several sub-texts to be considered here. The first point is that there
is no need to look upon the situation as a ``US versus Europe''
competition of an unhealthy type. It is more useful to consider our
European counterparts as worthy collaborators in our joint quest to
advance the knowledge in climate science. The investigation of climate
and climate change is a massive scientific problem, and requires vast
amounts of resources of various kinds in a globe-wide context, more
than any one country could possibly support. To address this complex
science, it is important to pursue the investigations in a cooperative
and collaborative sense, recognizing that scientists in Europe (and
elsewhere) may have as much and/or unique contributions to make to the
advancements. It is in fact the recognition of this complexity and the
need for a collaborative spirit that has led to IPCC's successful
evaluations of the climate science, guided strictly by scientific bases
and peer-reviewed publications. It is, however, incumbent upon US
scientists to bear in mind always the highest traditions of science,
and pursue the truth in an independent and original manner without
biases.
Secondly, compared to Europe, and seen in purely computational
facility and human brainware terms, it has become evident that the UK's
Hadley Center (under the UK Meteorological Office) made a very focussed
effort and posted substantive accomplishments, more than any other
center in the world, during the latter half of the 1990s decade. There
is one metric in particular that illustrates this point. The Hadley
Center model has performed stable climate simulation integrations in
excess of thousand years without flux adjustments--no other model in
the world has been able to perform such integrations without flux
adjustments/ corrections at the atmosphere-ocean interface. However,
this model has been the only European climate model that has eclipsed
the US achievements. It is important to note that no other model from
any of Europe's other climate science institutions can be said to be
more advanced than those in the US, with regards to the metric cited
above or, for that matter, other metrics of relevance for long-term
climate change.
It is a matter of considerable concern (and indeed has been
recognized to be so by the Academy report) that the computational
ability of the US has suffered a serious setback in the past few years.
While European institutions have not had to think of changing basic
architectures of their computational systems and have been able to
procure the fastest computers available, US institutions have found
their ability hampered in the procurements of the fastest computers in
the world. And, there have not been many competitive alternatives
available in this regard to the US institutions. Besides decelerating
the pace of scientific research in the US, this factor has also
initiated uncertainties about potential future computing frameworks for
climate modeling research.
It is unfortunate, too, that the brainpower (i.e. talented human
resources) needed to tackle the climate science problem has also
suffered in recent years in the US. While European institutions and
Hadley Center in particular have been able to ensure that funding and
institutional infrastructure continue to be favorable enough to attract
young students and scientists, such that they have been able to readily
recruit bright and talented youth emerging from the colleges, US has
lagged severely in this respect. Hadley Center has not only recruited
top-class youth but has also motivated them into focussed climate
modeling exercises. The problems in the US include: lack of resources
to motivate the top minds in the country to turn to and remain engaged
in science, declining base funding which barely if at all keeps pace
with inflation, and declining infrastructure resources with lack of
steady commitments to maintain top-class climate centers.
The above elements, while very crucial, have to be juxtaposed with
a third one that is at least equal in value to those stated above. This
concerns the question of extraction of science from the climate model
simulations and observations. Obviously, it is not just enough to have
the best computer, infrastructure and human resources. A key question
is how far has the science been actually advanced. Examination of
computer model simulations, critically analyzing them in conjunction
with observational data of various kinds, and making incisive and
proper diagnostic interpretations are the hallmarks of success in
scientific research. This element, together with the others above,
constitutes, in my view, the definition of the term ``modeling
capabilities''. In this regard, it is not at all clear that the US
contributions, in terms of the peer-reviewed findings reported in
journals or in the IPCC reports, are any less relevant in originality
and substance than contributions from Europe, including those from the
Hadley Center.
The Academy document, while rightly pointing out the limitations of
computer hardware and brainware, has chosen to critique a somewhat
narrower focus of the overall problem. It has not emphasized enough
that scientific accomplishments and advancement of knowledge in long-
term climate change require more than just hardware and brainware. In
particular, it has paid less emphasis to how the US has fared in the
third element mentioned above. While Hadley Center may have
unquestionably led in the implementation of the most sophisticated
physics and thus created the most stable climate model simulations to-
date, US institutions doing research in climate change have likely been
not far behind Hadley center in the overall diagnostic analyses of
climate change--forcings, feedbacks and responses. Compared to other
institutions in Europe, there is no question that the leading US
climate change research centers have at least been on par, if not
outshining them.
But, it is easy to become complacent. Thus, it is important that US
take firm, proactive steps to ensure sustained advancements in computer
power, assure itself of a continued stream of talent to engage in the
science, spot infrastructure deficiencies and build up with steady
commitments. In turn, it should be demanded that scientific research
continue to provide an unbiased, well-grounded and critical appraisal
of the understanding of climate change to policy makers.
Question 2. How many more scenarios were involved in this recent
assessment report as compared to five years ago? Would the scenarios
used 5 years ago result in the new predicted increases in sea level
rise and global-average surface temperatures?
Answer. The IPCC 1996 climate change science assessment employed
the IS92 suite of scenarios (6 in all), with the middle of the range
being the oft-mentioned IS92a scenario. In the 2001 assessment, the
calculations drew upon the IPCC Special Report on Emissions Scenarios
(SRES), besides also comparing the results with those from the IS92a
scenarios (see Figure 5, IPCC Summary for Policymakers). The SRES was a
separate study from the Working Group I climate change science
assessment. The SRES scenarios were drawn up based on a range of
diverse assumptions concerning future demographics, population
evolution, economic developments and technologies. While a few of these
new scenarios are similar to the IS92 set, some of the newer scenarios
differ markedly from the earlier ones employed by IPCC. There were
about 40 scenarios used in IPCC 2001, with 4 main groups or families,
and with 6 ``marker'' scenarios. As an example, the IS92a scenario
projection for carbon dioxide concentrations in this century is roughly
comparable to that for the A1B and A2 scenarios. The IS92 and the newer
scenarios represent quite a diverse collection of projections.
Nevertheless, it is emphasized that the projections should be
considered as sensitivity illustrations that employ a wide range of
assumptions for the purposes of obtaining insights into the plausible
projections of future climate changes due to anthropogenic emissions.
IPCC has discussed the projections of plausible future climates in
terms of a range that is a consequence of the variety in the scenario
assumptions. In arriving at the range of future climate change, IPCC
2001 considered the IS92 scenarios as well. The projections discussed
in the 2001 report yield a range that encompasses the results of the
IS92 scenarios, with the overall range wider now than in IPCC 1996. The
change in the range from IPCC 1996 is due in part to the several new
emission scenarios considered. The examination of both the IS92 and the
newer scenarios in the 2001 report achieves the intent of surveying the
effects due to an array of assumptions about emissions of radiatively-
active species. Thus, the IS92a scenario (BaU) results for global-mean
temperature and sea-level changes are indeed accounted for in the range
cited in the 2001 report.
An important technical difference between the older and newer
scenarios is the assumption of cleaner technologies in SRES which leads
to differing considerations of the relative amounts of the projected
concentrations of greenhouse gases and aerosols. In particular, the
aerosol concentrations are affected by an earlier invocation of cleaner
technologies in this century. As aerosols are short-lived, their
concentrations are affected right away. Thus, the sulfate aerosol
forcing concentrations (which yield a cooling) are projected to fall
faster in the newer scenarios than was the case in the IS92 (e.g.,
IS92a) scenario. Greenhouse gas concentrations (including
CO2) rise less rapidly than in IS92a for several, but not
all, of the newer scenarios. An additional feature in the IPCC 2001
report was to use the scenarios in conjunction with different model
climate sensitivities to approximately mimic the range in climate
sensitivity that arises owing to uncertainties in the physical
processes.
Taking into account the ranges provided by the assumptions leading
to the greenhouse gases and sulfur emissions, and the range in climate
sensitivity, the following results are cited by IPCC (2001). The
presently (and the most recently) cited range for the global-mean
surface temperature change projected in 2100 is 1.4 to 5.8 C; this is
to be contrasted with the range of 1 to 3.5 C in IPCC (1996). The main
reason for the upper end being greater and a wider range has to do with
the lower sulfur emission projections in the present report relative to
the IS92 scenarios. Lower sulfur emission means lesser importance of
the role of cooling effect by aerosols relative to the long-lived
greenhouse gases. The corresponding global sea-level rise in the 2001
report is 0.09 to 0.88 m. This is to be contrasted with 0.13 to 0.94 m
in the earlier report. Despite a higher temperature projected at the
upper end of the range, the sea-level projections are lower owing to
improvements in models that now yield a smaller contribution from
glacier and ice-sheet melts. It is reiterated that the scenarios used
five years ago yield results that are within the range spelt out in the
2001 report.
Question 3. You have stated that a key aspect of climate change is
that a greenhouse gas warming could be reversed only very slowly. Can
you elaborate on that point and also comment on the value in
sequestration in this process?
Answer. The major greenhouse gas being input into the atmosphere,
CO2, has a long residence time owing to its chemical
inertness. Its sinks act quite slowly; in particular, mixing into the
oceans is very slow. Thus, it is expected that it would take a long
time (centuries) to draw down the CO2 that has been emitted.
Other greenhouse gases, which are less strong climate forcing agents
compared to CO2, can be just as long-lived. In a general
sense, there are several important climate forcing gases, with
lifetimes varying from ten to upwards of hundred years (e.g., methane,
nitrous oxide, halocarbons, sulfur hexafluoride). With the CO2
sinks tending to operate slowly, even if it were assumed that all
emissions ceased at present, there would tend to be only a slow
decrease in the atmospheric CO2 concentration.
The long residence time factor implies that the radiative forcing
due to the emitted CO2 will act for a long period of time.
In addition, there is another timescale that has to be taken into
account. This concerns the delay in the thermal response of the oceans
owing to the long time it takes for heat to be diffused into or out of
the deep ocean. At present, the climate is not in equilibrium with the
present atmospheric CO2 implying that the complete impact of
present-day CO2 is yet to be fully realized. Thus, while
atmospheric CO2 is not in equilibrium with the present
emissions, the climate is not in equilibrium with the present-day
atmospheric concentrations. Thus, even if the atmospheric CO2
concentration were to be stabilized at a particular value and at a
particular time, the climate effects can be expected to be felt well
after this point is reached e.g., continued sea-level rise. The longer
this forcing element is there in the atmosphere, the further the delay
in the recovery of the climate system. In view of the slow but long
associated timescales, greenhouse gas warming can be reversed only very
slowly. In this regard, the possibility of non-linear and irreversible
climate changes owing to feedback mechanisms existing in the system
cannot be overlooked.
Sequestration process, meaning a mechanism to draw down the
CO2 thus reducing its atmospheric composition, would
presumably achieve the objective of lowering the quantum of this
forcing agent in the atmosphere. This is a conceptually attractive idea
and one that is engaging vigorous research attention. Thus far,
however, the research has yet to be translated in robust quantitative
and practical terms, including cost-effectiveness. Early results are
somewhat tentative on the overall effectiveness and scaling with
respect to natural sinks, especially on multi-decadal to multi-century
time scales. Note that even if it were possible to sequester all future
CO2 emissions, climate would still continue to warm and sea-
levels would continue to rise, as noted above, because of the slow
climate response to the existing atmospheric concentrations.
Nonetheless, there are some interesting ideas concerning sequestration
under active investigation which may shed further insights into this
problem in the near future.
Question 4. The report states that a special need is to increase
the observational and research capabilities in many regions,
particularly in developing countries. How is this need being addressed
by the International community and how much will it cost?
Answer. I will confine my remarks here only to the principal
shortcomings. A key point to note is that observational networks are on
the decline. Long-term monitoring of climate variables--even the most
common and obvious ones, such as surface temperature and precipitation,
are not being done with the spatial distribution and frequency that is
necessary to achieve a comprehensive documentation of regional climate
variations and change. The problem exists to varying degrees in all
parts of the world, but is especially acute in the developing
countries. Lack of adequate and sustained funding, the high cost of
initiating and maintaining reliably measuring equipment, are major
issues. There are, however, other factors as well, such as the lack of
an appreciation of the significance of long-term monitoring, which
inhibits a sustained high-quality data collection. Further, data
gathering tends to not be a high-visibility exercise. The worth of such
routine measurements does not really show up till at least a decade's
worth of data has been collected. By then, due attention to such
important technical issues as instrument maintenance and consistency in
program management usually tend to wane, resulting in the difficulty of
compiling a reliable dataset. Insofar as developing countries are
concerned, the problems include acquisition of state-of-the-art
equipment, ability to sustain funds for maintenance, and quality
control. A recurring problem is the lack of well-trained human-power.
As is true even the developed world, the scientific challenge posed by
climate change detection is unable to compete with the marketplace
attraction of other professions. Very few scientists' careers have
advanced solely as a consequence of painstaking data collection over a
long period of time, a timescale that is also considerably longer than
typical program management tenure and fiscal considerations. Thus,
especially among young scientists worldwide, there is a lack of a
motivation to undertake these routine but necessary observations. This
holds true in both developed and developing countries.
Automation and advances in remote sensing, which would obviate the
need for humans to attend to the observational tasks, are not yet in
full gear in this field in the developing countries. Amidst the
pessimism, however, it is important to point out that some
observational activities have indeed flourished e.g., measurements of
CO2 at a few sites around the world for the past 3 decades
and more. This effort is particularly exemplary and is worth emulating
for other climate variables as well.
The situation with regards to modeling capabilities, and diagnostic
analyses combining models and observations is not dissimilar from the
tenor of the issues plaguing observational datasets, as noted above.
The lack of talented minds applying themselves to science in general
and to this scientific aspect in particular needs to be improved. There
is a need to improve this situation especially in the developing
countries, where the educational and scientific infrastructure are at
times too weak to sustain a orderly, long-term research commitment.
International research organizations are trying hard to remedy the
situation, but are being strained by funding inadequacy and the need to
keep pace with the growing complexity of the climate system.
Question 5. What would you say is most urgent in terms of future
research needs?
Answer. It is useful to summarize here IPCC 2001 `s statements on
future research needs. These are an appropriate recognition of the
needs in the present times, based on considerations stemming from the
current assessment of climate change science. Note that IPCC itself
does not make any recommendations on prioritization or funding plans,
nor is it associated with or endorses any national/international
programs.
First, systematic observations and reconstructions of past climates
need to be sustained and improved wherever possible. Observations
include those that are designed to understand the processes, as well as
those that are specifically geared towards long-term monitoring of key
climate variables. The elements include: arresting and reversing the
decline of observational networks; sustaining and expanding the
observational foundation of climate studies by providing accurate,
long-term, highly reliable and consistent data, including
implementation of strategies for integrated and well-coordinated global
observations; enhancing development of reconstruction of past climate
periods; improving observations of the spatial and temporal
distributions of greenhouse gases and aerosols; sustaining measurements
that monitor forcing agents and climate feedback processes;
improvements in observations of the world's oceans including ocean
thermal changes (this may prove to be an optimal item to measure the
increasing heat content of the climate system).
Second, improvements in modelling and process studies are needed to
improve the quantitative realism of the simulated climate system. These
include: improved understanding of the physical and chemical mechanisms
that lead to a forcing of climate change; understanding and
characterizing the important unresolved processes, and physical and
biogeochemical feedbacks in the climate system; improved methods to
quantify uncertainties of climate projections and scenarios, including
long-term ensemble simulations using complex but well-understood
models; improving the integrated hierarchy of global and regional
climate models, with a focus on the simulations of climate variability,
regional climate changes and extreme events; linking more effectively
models of the physical climate and the biogeochemical system, and in
turn improving the coupling with other factors intrinsically associated
with human activities.
There is a vital research element to be added to the above viz., an
appropriate synthesis of the observations and model simulations leading
to a scientifically, well-grounded picture of climate change and its
causes. Rigorous diagnostic analyses of observations and model
simulations are critically needed in unravelling the evolution of
climate change. Lastly, in the sequence, it cannot be overemphasized
enough that each successive piece of knowledge gained, whether in
modeling, observations or diagnostic analyses, needs to be gainfully
used to plan better observational strategies and to improve further
upon the model simulations/projections of climate change.
It is vital that there be a balanced approach that weighs in both
observations and modeling studies. In particular, the build-up of the
infrastructure and funding plans must recognize this point. For
instance, observations should guide the science of what forcings are
operating, what are the feedbacks, how should we be modeling these,
what are the results of the simulations, how robust are they, how do
they compare with various climate parameters, why is there a
disagreement or why is there a good agreement, what can we relay back
to the observational infrastructure so that they can receive better
guidance. The idea should be to continually enhance the confidence in
the climate forcings, feedback mechanisms, and responses, consistent
with the central focus of understanding climate variations and changes.
Question 6. You have mentioned that the best agreement between
observations and model simulations over the past 140 years is found
when both human-related and natural climate-change agents are included
in the simulations. Why is it important for the model simulation to
include both?
Answer. In order to investigate the long-term climate change, model
simulations of climate change have considered four different
possibilities: (a) unforced internal variability of the nonlinear
coupled atmosphere-ocean system i.e., the climate variations that occur
even in the absence of any forcing; (b) climate change due to the
introduction of ``natural'' factors such as solar irradiance changes
and volcano-induced enhancement of stratospheric aerosol
concentrations; (c) climate changes when only ``anthropogenic'' factors
(e.g., emissions of greenhouse gases and aerosols) are considered; and
(d) when all the factors are considered in unison. This modus operandi
enables the identification of specific causal factors and aids in
framing the detection-attribution analyses.
The climate model simulations performed indicate that it is very
unlikely that internal variability of the climate system alone can
explain the past 140 years' observed surface temperature record. Three
different models (one of them from NOAA) are in agreement on this
finding. The models' surface temperature interdecadal variation is not
inconsistent with that observed over the past 140 years. A model
simulation without consideration of the water vapor feedback yields far
less variability than evidenced in the observations, suggesting that
the manner in which this feedback is represented in the models may be
qualitatively consistent with reality. Owing to the lack of a long
record in atmospheric observations, there tends to be a reliance on
climate models for estimates of the unforced climate variability.
Although this is a limitation, there are tests that climate models have
successfully met in this regard.
``Natural'' factors alone cannot account for the observed warming
over the past 140 years, although there are suggestions that over the
first half of the 20th century, these factors may have contributed to
the warming occurring at that time. In particular, solar irradiance
changes may have contributed to the observed warming during the first
half of the 20th century. Although episodic volcanic eruptions exert
impacts during the 1-2 years that they enhance stratospheric aerosol
concentrations, their effects over the past century are less relative
to those due to the secular changes in greenhouse gases. Model
simulations with ``anthropogenic'' factors alone indicate that, despite
uncertainties in the quantitative estimates of the forcing, their
influence in the model simulations can be associated with the rapid
rise in the observed warming over the latter half of the 20th century.
When considering the entire modern instrumental surface temperature
record, it becomes clear that both ``natural'' and ``anthropogenic''
factors need to be considered for the simulation of the observed
temperature record. This includes the Sun's output changes as well as
the particularly active volcanic period in the 1880-1920 and 1960-1991
time periods. For a proper explanation of climate change, and to
distinguish between the natural factors and anthropogenic species,
these factors must be juxtaposed with the internally generated
variability.
______
Response to Written Questions Submitted by Hon. John McCain
to James J. McCarthy
Question 1. Why would climate changes in the 21st century be 2-10
times faster than those of the 19th century?
Answer. On pp. 30-31 of the oral testimony transcript I am
correctly quoted as having made a statement like this in comparing
rates of climate change between the 21st century and the 20th (not the
19th) century.
More specifically, this comparison is between the rates of global
mean temperature change. For the 20th century this rate was 0.6C (1.0F)
per century. For the 21st century, the scenarios project a range of
increases between 1.4C (2.5F) and 5.8C (10F). This comparison is the
root of the 2-10 fold comparisons.
Question 2. Your written testimony states that even the most
optimistic scenarios for mitigating future climate change are unlikely
to prevent significant damage from occurring. What type of events would
qualify as significant damage?
Answer. Extrapolating from the changes that have occurred in the
last few decades in the distributions and timing of seasonal biological
phenomena, accelerating some of these by 2-10 times in the current
century may push some species over the edge. Prime examples are
tropical and Arctic systems, where temperature limits for some species
like coral may be exceeded, and the ice habitat for many organisms,
like pregnant polar bears needing the high fat nourishment of seals,
may be lost.
Most problematic, though, are the impacts on human systems related
to extreme climate events. Table 1 in the Working Group I SPM indicates
levels of confidence in extreme weather and climate observations over
the past 50 years and projections in the next 50 years. Table 1 in the
Working Group II SPM lists representative examples of projected impacts
from these extreme events. Extrapolating from the tolls in lives,
livelihoods, and properties caused by the flood and mudslide disasters
in the past 5-10 years to the projected future provides good examples
of likely significant damage.
Question 3. There has been and continues to be a major discussion
on how to reduce emissions. How can we best prepare people and systems
for the disruption that will ensue with the climate change that is now
projected for the 21st century?
Answer. This is in my estimation one of the most critical questions
that we face. The scenarios mentioned above that yield the range of
1.4-5.8C increases are representatives of classes of scenarios (35 were
used) that have several variable components. These include the
projections for human population numbers over the next century, our
standard of living and socioeconomic conditions in the developed and
developing world, and the fossil-fuel intensity of our energy producing
activities. The last of these is the one that is most easily altered
with minimal impact on the other conditions.
While an optimist will suggest that it is unlikely that we will
climb steeply up the highest of these slopes, a realist will also
suggest that it is unlikely that we be able to stay close to the lowest
of these slopes. Partly this is due to the socioeconomic and
geophysical inertia in our energy systems. While it is easier to
modulate the use of fossil fuel, and especially to switch to
alternative sources of energy, than it is to reduce the world's human
population numbers, the difficulties in changing human behavior and
human institutions are enormous. At the same time, since CO2
emitted today will be still be in the atmosphere a century from now,
everything we do now to reduce rates of emission will pay increasing
dividends in the future.
This having been said, it is clear that we must also prepare for
the sort of increasing prospect of damage mentioned in #2 above by
enhancing adaptation. This is particularly critical in the regions
hardest hit where adaptive capacity is the least (tropics and
subtropics). Serious attention must be given to the potential impacts
on the availability of safe water, subsistence agriculture, and human
health.
How the scenarios mentioned above play out will greatly influence
the rate of sea level rise. A large component of sea level rise is due
to the expansion of the ocean as it warms. The convection of heat from
the surface ocean to deeper waters is a slow process. A greater rate of
atmospheric warming early in this century followed by a slower rate of
warming later in the century will have a stronger effect on sea level
rise within the next 100 years than a slow warming followed by a fast
warming that would have atmospheric temperature at the same point 100
years from now. Coastal zones and small island states are vulnerable to
this aspect of climate change and even more so with increases in peak
storm wind and precipitation intensities. Planning for coastal human
settlements, their infrastructures, and resources (like ground water)
must be prepared to consider adaptive strategies that can minimize
these impacts. Indigenous communities may in some instances be
especially vulnerable, such as in the case mentioned for Alaska by
Senator Stevens.
Question 4. Can you discuss some of the impacts of climate change
on public health?
Answer. Impacts of potential climate change on human health are
given a full chapter in the Working Group II report, and this is
summarized in section 3.5 of the SPM. Broad categories include negative
consequences of increasing thermal stress, the impacts of storms, and
increases in the areal extent or seasonal duration of certain
infectious diseases. In some areas there may be positive aspects of
climate change for human health, such as with diminished winter
mortality, but it is important to emphasize that the negative aspects
will disproportionately hit the tropical and subtropical regions. An
obvious adaptive strategy would be to enhance public health
institutions and resources. Since these are woefully inadequate in many
areas today, successful adaptation will take a concerted effort the
likes of which is without any obvious precedent.
Question 5. How significant was last summer('s) passage of a ship
through the Northwest Passage without touching ice? Has shipping
traffic increased?
Answer. There is something symbolic and sobering about this
observation. Had it occurred any time before in the last 150-200 years
it would have been evident in the accounts of sealing and exploring
vessels. It is possible that the thinning and loss of areal extent of
summer ice in the Arctic Ocean and adjacent regions may be the result
of a long term natural cycle, but the period of such a cycle must be
longer than a few hundred years, and no known or hypothesized mechanism
has this potential. Climate models have forecast diminished Arctic
summer ice with continued greenhouse gas--forced warming, but the rates
were less than has been observed in the last few years.
At this moment there are probably many commercial enterprises that
are exploring options for capitalizing on the diminished ice in the
Northwest Passage. Canadian claims regarding access through its Arctic
archipelago are certainly an issue that that will require careful
consideration by nations wishing to anticipate increased shipping
potential through the Northwest Passage.
Question 6. You have mentioned how some species are being driven
from their natural habitats because of changing environmental
conditions due to increasing temperatures. How many species have been
declared extinct because of these weather patterns changes?
Answer. As I stated in my testimony, it is not clear that any of
the changes in distribution of species and the timing of biological
processes (that can be plausibly liked to local climate change) have
led to the loss of any species. Habitat destruction and the intentional
and accidental introduction of invasive species have caused several
extinctions, especially on islands. These may continue to be larger
factors than climate change with regard to extinctions, but in the
Arctic and the tropical ocean this condition may not hold--climate
change may dominate. There are synergistic interactions among some of
these factors, such as climate change prompting relocation of species,
which is then hindered by land-use change that has interrupted
migration corridors.
______
Response to Written Questions Submitted by Hon. John McCain
to Dr. James E. Hansen
Question 1a. You mentioned that your alternative scenario assumes
that air pollution is not allowed to get any worse than it is today and
that global use of fossil fuels will continue at about today's rate. It
also assumes no net growth of the other forcings. What are those other
forcings?
Answer. They are included in Figure 2 of my submitted testimony.
Chief among them are methane, tropospheric ozone and black carbon
(soot) aerosols.
Question 1b. Does the IPCC business as usual scenario assume that
air pollution is stable?
Answer. No, They have ozone and methane increasing substantially.
In addition, they grossly underestimate the climate forcing by black
carbon, and thus their scenarios tend to ignore it. Since air pollution
is excluded from the Kyoto Protocol, it receives little attention in
the IPCC scenarios.
Question 1c. Do these differences in assumption account for the
differences in expected temperature increases in the next 50 years for
the two scenarios? And again what are the temperature differences?
Answer. As shown in Figure 5 of my submitted testimony the
additional warming in the next 50 years is about 1.6C in the business-
as-usual scenario and about 0.75C in our alternative scenario.
Moreover, the business-as-usual scenario ``builds in'' a much larger
later warming, which will appear in the latter half of the century.
The smaller warming in the alternative scenario is due to the two
assumptions: (1) it will be possible to stop further growth of non-
CO2 forcings (loosely labeled ``air pollution''),
particularly ozone, black carbon and methane, (2) it will be possible
to keep the growth of atmospheric CO2 to about 75 parts per
million in the next 50 years, which would require that CO2
emissions remain roughly similar to today's rate or decline slightly.
Question 2. You mentioned in your statement that the judge of
science is observations. You also mentioned the potential educational
value of keeping an annual public scorecard of measured changes. Can
you elaborate on this idea?
Answer. It is briefly elaborated upon in reference 22 of my
submitted testimony, where I mention an annual public scorecard of (1)
fossil fuel CO2 emissions, (2) atmospheric CO2
amount, (3) human made climate forcing, (4) global temperature. I will
try to write a paper with a more a more comprehensive discussion in the
near future. One obvious addition would be an annual measure of
CH4 emissions and atmospheric amounts. However, the single
most important benchmark for the United States is probably an annual
update of the bar graph in Figure 11 of my testimony. i.e., the annual
growth of CO2 emissions the annual growth needs to be
reduced to zero or slightly negative.
Question 3. Do you feel that your results were reviewed and
properly considered as part of the IPCC process?
Answer. No. IPCC's size and review procedures make it inherently
lethargic, so responding to a mid-2000 paper is difficult. However, the
real problem is probably the close binding between IPCC and the Kyoto
Protocol discussions. Kyoto excludes consideration of air pollution
(such as tropospheric ozone and black carbon), for example, so IPCC
basically ignores these topics and downgrades them. The only IPCC
``review'' of our paper was by the IPCC leaders (as reported in the New
York Times, for example), who saw our paper as potentially harmful to
Kyoto discussions. They received the backing of organizations (such as
the Union of Concerned Scientists, who commissioned a criticism of our
paper that I respond to in reference 22) and publications (particularly
Nature), who had previous editorial positions favoring the Kyoto
Protocol. When I had difficulty publishing a response in Nature, I
wrote an open letter that is available at http://naturalscience.com/ns/
letters/ns--let25.html.
Question 4. You mentioned that the climate cannot respond
immediately to a forcing because of the long time needed to warm the
oceans. How would we measure the real impact of reducing the amount of
greenhouse gases in the atmosphere in the short term?
Answer. We should of course measure the individual greenhouse gases
as the best measure of short-term effectiveness of any attempts to
reduce emissions. However, the best measure of the impact of the net
climate forcing is likely to be heat storage in the ocean. Natural
variations of this rate will occur because of the dynamics of the
system. but if the measurements are accurate and maintained for years
they will soon begin to provide us with a great tool for understanding
where the future climate is heading.
______
A Brighter Future--by Dr. James E. Hansen
Contrary to Wuebbles' thesis (2002), most of the media did not
misunderstand the thrust of our recent paper (Hansen et al., 2000). We
do indeed assert that a scenario is feasible in which the rate of
global warming declines. We also posit that, with an understanding of
the significant climate forcings, it is possible to achieve such a
climatically brighter path with actions that are not ``economically
wrenching'', indeed, actions that make economic sense independent of
global warming.
Our paper does not denigrate the ``business-as-usual'' (BAU)
scenario that has been popular in global climate model simulations. The
BAU scenario provides a valuable warning of potential climate change if
the world follows a path with climate forcings growing more and more
rapidly. Our aim was to present a companion scenario that stimulates
discussion of actions that help avoid a gloom and doom scenario. I
tried to clarify our objectives in an ``Open Letter'', which is made
available from Climatic Change I summarize here key points of
discussion.
Black Carbon (BC). One of our assertions is that BC (soot) plays a
greater role in climate change than has been appreciated. We believe
that the forcing due to BC is of the order of 1 W/m\2\, rather than of
the order of 0.1 W/m\2\, as assumed by IPCC (1996).
My present estimate for global climate forcings caused by BC is:
(1) 0.40.2 W/m\2\ direct effect, (2) 03015 W/
m\2\ semi-direct effect (reduction of low-level clouds due to BC
heating; Hansen et al., 1997), (3) 0.10.05 W/m\2\ ``dirty
clouds'' due to BC droplet nuclei, (4) 0.20.01 W/m\2\ snow
and ice darkening due to BC deposition. These estimates will be
discussed in a paper in preparation. The uncertainty estimates are
subjective. The net BC forcing implied is 10.3 W/m\2\.
Air Pollution. Aerosols and tropospheric ozone (O3) are
not addressed by the Kyoto protocol. They should be. A reason proffered
for excluding ozone is that its chemistry is so complex that ``most
scientists'' eyes glaze over'' (Revkin, 2000). Perhaps the latter
assertion is true. But it is not adequate reason to exclude air
pollution from international climate negotiations. Our estimated
anthropogenic global climate forcing due to BC (1 W/m\2\) and O3
(0.4 W/m\2\) is comparable to the CO2 forcing (1.4 W/m\2\).
One thesis in our paper is that halting the growth of air pollution can
make a significant contribution to slowing global warming.
Effects of air pollution on humans are large in the developed world
and staggering in the developing world. A recent study (Kunzli et al.,
2000) estimates that particulate air pollution in France, Austria and
Switzerland takes 40,000 lives annually with health costs equal to 1.6%
of the gross national products. An example for the developing world is
the estimate (Smith, 2000) that 270,000 Indian children under 5 years
old die annually from acute respiratory infections caused by air
pollution. Most of the pollution in this latter case arises from indoor
combustion for cooking and heating, a primary source of the cloud of
pollutants now mushrooming from India and China. Aerosols and ozone
also reduce agricultural productivity with costs of many billions of
dollars.
Practical benefits of air pollution reduction accrue immediately,
not in 100 years. We assert in our paper that this offers an
opportunity to reduce the climate problem with a cooperative approach
that has immediate clear benefits to both developing and developed
countries.
Methane. We conclude that climate forcing by CH4 is 0.7
W/m\2\, fully half as large as the forcing by CO2. Observed
growth of CH4 is not accelerating, contrary to assumptions
in many climate scenarios. Indeed, the growth rate has declined by two-
thirds in the past 20 years. However, future trends are uncertain.
The task of understanding CH4 should be jumped on, like
a chicken on a June bug. Yet research support has been minuscule. We
need quantitative understanding of CH4 sources and sinks to
define optimum policies. It may be possible to find practices that
reduce methane emissions while saving money. Farmers want cows and
beasts of burden to produce milk, meat, and power, not methane. Rice
growers seek food and fiber, not methane, but we must also compare
impacts of altered practices on N2O production. There is
much potential for methane capture via improved mining and waste
management practices.
Scenarios. Science works via iterative comparison of theory and
observations. Differences found are not a problem--on the contrary,
only by discovering and investigating these can our understanding
advance. One problem with the IPCC reports is that each report produces
new (and more numerous) greenhouse gas scenarios with little attempt to
discuss what went wrong with the previous ones. As a result, dramatic
changes that have occurred since the 1980s in prospects for future
climate forcings receive inadequate attention.
Figure 1 shows climate forcing scenarios used for climate
simulations in the 1980s (Hansen et al., 1988). The actual climate
forcing in 2000 is close to that of scenario B, and the derivative
(growth rate) is less than that of scenario B. Further slowdown is
needed to achieve the path of the ``alternative scenario''. The fact
that the real world does not now seem to be following a path toward the
median of the greenhouse gas amounts projected by Ramanathan et al.
(1985) for 2030 in no way detracts from that paper, which, in my
opinion, was one of the most stimulating papers in atmospheric sciences
during recent decades. Indeed, to at least a small extent, one might
credit the slowdown in climate forcing growth rates to the warning
implicit in this and related papers.
Why have growth-rates fallen below BAU scenarios? One clear reason:
the Montreal Protocol, which forced a phase-out of CFCs. That is an
example of what we propose: actions useful for other reasons that also
help to slow climate change. Reasons for the decline in the CH4
growth rate need to be understood better. The apparent flattening of
the CO2 growth rate is probably due in part to an increased
CO2 sink, which may (or may not) be a temporary phenomenon.
CO2 scenarios are the most critical. Our approach,
characterized as naive by Wuebbles, emphasizes observations. We note
that the growth rate of CO2 (fossil fuel) emissions has
declined from about 4%/year to 1%/year in recent decades. It is
noteworthy that the current IPCC (2001) scenarios have a growth rate in
the 1990s that is almost double the observed rate of 0.8%/year (linear
trend fit to 5-year running mean), but it is consistent with their
failure to emphasize data. I will not characterize the IPCC approach
defended by Wuebbles, but I note in my open letter the difficulty
inherent in multiplying assumptions about population, economic
development, and technology 50 or 100 years in the future. In my letter
I specifically discuss their population estimates, which already appear
to be unduly pessimistic.
Media and the Public. Wuebbles claims that the press misunderstood
our paper. I believe that he fails to see the forest for the trees. The
media do not always get technical details correct, as scientists know
well. Moreover, media often have editorial positions and put their own
spin on news stories. I complain in my open letter about an exceptional
case in which Nature disguised their editorial position as a ``news''
article in which they report only criticisms of our paper. However,
overall the media deserve credit for correctly conveying the thrust of
our perspective on climate change. Indeed, the Washington Post
editorial discussed in my open letter is, in my opinion, an astute
assessment of the issues.
A basic problem is that we scientists have not informed the public
well about the nature of research. There is no fixed ``truth''
delivered by some body of ``experts''. Doubt and uncertainty are the
essential ingredient in science. They drive investigation and
hypotheses, leading to predictions. Observations are the judge.
Sure, some things are known with higher confidence than others. Yet
fundamental issues as well as details are continually questioned. The
possibility of finding a new interpretation of data, which provides
better insight into how something in nature works, is what makes
science exciting. A new interpretation must satisfy all the data that
the old theory fit, as well as make predictions that can be checked.
The suggestion that BC causes a forcing of about 1 W/m\2\ is a
possible example. Observations required to verify the forcing are
extensive, because it is the sum of several effects. Perhaps
recognition of the BC forcing will allow IPCC to include fully the
negative direct and indirect forcings of sulfate and organic aerosols,
something that they have been reluctant to do. There is still much to
be learned.
In my letter I note the potential educational value of keeping an
annual public scorecard of measured changes of (1) fossil fuel CO2
emissions, (2) atmospheric CO2 amount, (3) human-made
climate forcing, and (4) global temperature. These are well-defined
quantities with hypothesized relationships. It is possible to make the
science understandable, and it may aid the discussions that will need
to occur as years and decades pass. It may help us scientists too. I am
curious, for example, whether the IPCC (1996) conclusion that fossil
fuel CO2 emissions must be cut by 80% to stabilize
atmospheric CO2 at 550 ppm will be supported by empirical
data as it accumulates.
Strategic Considerations. Wuebbles states that our scenario can not
be ``used in any sense as a strategy, particularly given the
inhomogeneities in the aerosol distribution and radiative forcing''. We
do not try to specify a detailed strategy for dealing with global
warming (nor does Wuebbles or IPCC). However, we do present an outline
of a strategy and argue that its elements are feasible.
It is impractical to stop CO2 from increasing in the
near term, as fossil fuels are the engine of the global economy.
However, the decline of the growth rate of CO2 emissions
from 4 to 1%/year suggests that further reduction to constant emissions
is feasible, especially since countries such as the United States have
made only modest efforts at conservation. The potential economic and
strategic gains from reduced energy imports themselves warrant the
required efforts in energy conservation and development of alternative
energy sources.
The other requirement in our alternative scenario is to stop the
growth of non-CO2 forcings, which means, primarily, air
pollution and methane. The required actions make practical sense, but
they will not happen automatically and defining the optimum approach
requires research.
A strategic advantage of halting the growth of non-CO2
forcings is that it will make it practical to stop the growth of
climate forcings entirely, in the event that climate change approaches
unacceptable levels. The rationale for that claim is that an ever-
growing fraction of energy use is in the form of clean electrical
energy distributed by electrical grids. If improved energy efficiency
and non-fossil energy sources prove inadequate to slow climate change,
we may choose to capture CO2 at power plants for
sequestration.
Global warming is a long-term problem. Strategies will need to be
adjusted as we go along. However, it is important to start now with
common sense economically sound steps that slow emissions of greenhouse
gases, including CO2, and air pollution. Early emphasis on
air pollution has multiple immediate benefits, including the potential
to unite interests of developed and developing countries. Barriers to
energy efficiency need to be removed. Research and development of
alternative energies should be supported, including a hard look at next
generation nuclear power. Ultimately strategic decisions rest with the
public and their representatives, but for that reason we need to make
the science and alternative scenarios clearer.
Finally, an amusing thing about Wuebbles'' criticism is the space
devoted to noting that, even if there is some cancellation of global
mean forcings by aerosols and gases, there may still be climate effects
due to the geographical inhomogeneity of the net forcing. That's right.
However, he fails to recognize that reduction of particulate air
pollution will reduce this inhomogeneity, not increase it.
references
Hansen, J., Fung, I., Lacis, A., Rind, D., Lebedeff, S., Ruedy, R.,
Russell, G., and Stone, P.: 1988, ``Global Climate Changes as Forecast
of Goddard Institute for Space Studies Three-Dimensional Model'', J.
Geophys. Res. 93, 9341-9364.
Hansen, J., Sato, M., and Ruedy, R.: 1997, ``Radiative Forcing and
Climate Response'', J. Geophys. Res. 102, 831-6864.
Hansen, J., Sato,M., Ruedy, R., Lacis, A., and Oinas, V.: 2000,
``GlobalWarming in the Twenty-First Century: An Alternative Scenario'',
Proc. Nat. Acad. Sci. 97, 9875-9880.
Intergovernmental Panel on Climate Change: 1996, in Houghton, J.
T., Meira Filho, L. G., Callander, B. A., Harris, N., Kattenberg and
Maskell, K. (eds.), Climate Change 1995, Cambridge University Press, p.
572.
Kunzli, N., Kaiser, R., Medina, S., Studnicka, M., Chanel, O.,
Filliger, P., Herry, M., Horak, F., Puybonnieux-Texier, V., Quenel, P.,
Schneider, J., Seethaler, R., Vergnaud, J. C., and Sommer, H.: 2000,
``Public-Health Impact of Outdoor and Traffic-Related Air Pollution: A
European Assessment'', The Lancet 356, 795-801.
Ramanathan, V., Cicerone, R. J., Singh, H. B., and Kiehl, J. T.:
1985, ``Trace Gas Trends and their Potential Role in Climate Change'',
J. Geophys. Res. 90, 5547-5566.
Revkin, A. C.: 2000, ``Debate Rises over a Quick(er) Climate Fix'',
New York Times, October 3.
Smith, K. R.: 2000, ``National Burden of Disease in India from
Indoor Air Pollution'', Proc. Nat. Acad. Sci. 97, 13286-13293.
[GRAPHIC] [TIFF OMITTED]
[From The Washington Post, August 28, 2000]
Hot News on Warming
If you're trying to decide whether to be an optimist or a pessimist
on global warming, recent news is enough to leave you dizzy. An
icebreaker found open water at the North Pole, prompting a new wave of
attention to the thinning polar ice cap. That seemed like bad news,
although some oceanographers said summertime cracks in Arctic ice
aren't new, and this one shouldn't be over-interpreted. Texas, the
state that produces the most greenhouse gas emissions, for the first
time took steps to study the extent of those emissions and consider
possible ways to reduce them. That was good news, although it doesn't
guarantee state action. And Dr. James Hansen, a leader in drawing
government attention to global warming, published a report suggesting
that it may be ``more practical to slow global warming than is
sometimes assumed'' by focusing in the short term on cutting heat-
trapping gases other than carbon dioxide. That was surprising news, at
least to those of us who have seen the climate-change fight centering
on reducing carbon dioxide emissions.
It's long been known that carbon dioxide isn't the only gas that
helps hold heat in the atmosphere. Six ``greenhouse gases'' were
included in the Kyoto protocol, the international agreement that calls
for cutting emissions by 2012. But carbon dioxide, the most abundant
greenhouse gas, has dominated the public debate. It has been a subject
of contention because it is a byproduct of burning fossil fuels, such
as coal and gas, that drive modern industrial society. American
opponents of the Kyoto protocol have argued that the reductions it
requires could wreck the economy.
Dr. Hansen and a team of colleagues wrote that most of the global
warming so far observed actually has come from other greenhouse gases
such as methane, chlorofluorocarbons, and gases that combine to create
ozone in smog. They suggested a strategy of focusing first on cutting
those gases and black particles of soot that also trap heat. Some of
the gases involved are already in decline because of other
international restrictions; going after others amounts to an attack on
air pollution, which the scientists argue should be attractive action
in all parts of the world, independent of concerns about warming,
because of the health benefits of cleaner air.
That optimistic scenario immediately caused some environmentalists
to worry that the report would become a weapon for those who are
skeptical about warming--who oppose any action. Dr. Hansen himself said
it undoubtedly will be used that way, but that would be a misreading of
the study. The new report does not challenge either the evidence that
surface temperatures are going up or the growing consensus that human
activities are contributing to the increase. It continues to cite the
need for reductions in carbon dioxide emissions. There is no
suggestion, nor should there be, that response to global warming should
wait until the science is more certain.
What it does do is remind us that climate issues are complex, far
from fully understood and open to a variety of approaches. It should
serve as a caution to environmentalists so certain of their position
that they're willing to advocate radical solutions, no matter what the
economic cost. It suggests that the sensible course is to move ahead
with a strong dose of realism and flexibility, focusing on approaches
that are economically viable, that serve other useful purposes such as
cutting dependence on foreign oil or improving public health, and that
can help support international consensus for addressing climate change.
If the Hansen report pushes the discussion in that direction, it will
turn out to be good news indeed.
______
[From the International Herald Tribune, November 16, 2000]
Try a Commonsense Response to Global Warming
(By James Hansen)
New York.--Evidence continues to build that the world is slowly
getting warmer. Almost all mountain glaciers are retreating. It was
discovered this year that even the deep ocean is warming. On Earth's
surface, where people live, the average warming is now about half a
centigrade degree in the past 100 years.
Half a degree seems hardly noticeable. It is much less than weather
fluctuations that occur every day. But it is a warning of possibly
large climate changes as the 21st century progresses.
One worry is sea level, which will rise as glaciers melt and as
ocean water expands from warming. A rise of a meter, a possibility this
century, would submerge island nations such as the Maldives and the
Marshall Islands, and it would be devastating to people living in
Bangladesh and on the Nile Delta.
The greatest effect of global warming for most people may be an
increase in extreme weather. Global warming is expected to cause more
droughts and forest fires. It increases evaporation, which will lead,
at other times and places, to heavier rainfall and floods.
The forces that drive global warming are no surprise. They are
mainly the gases and fine particles that humans have been dumping into
the atmosphere for many years. The gases, especially carbon dioxide and
methane, absorb Earth's heat radiation and thus warm the surface, just
as a blanket traps body heat. Fine particles of soot (black carbon)
warm the air by absorbing sunlight.
Other human-made fine particles, especially sulfates, are nearly
white. Sulfates come from sulfur in coal and oil, which is released to
the atmosphere when these fossil fuels are burned. Sulfates cool Earth
by reflecting sunlight back to space.
The net effect of these human emissions is not accurately known,
because the fine particles are not yet measured well. But it is
estimated that the net heating is at least one watt, perhaps closer to
two watts, per square meter. Such a human forcing of climate is
comparable to increasing the brightness of the sun by 1 percent.
Earth responds slowly to such forcings. The thermal inertia of the
ocean delays the response. It takes decades for most of the response to
occur, and centuries for the full response.
The question we face today is how much more we should allow human
climate forcing to grow. That question is being addressed now in The
Hague by the world's nations.
These deliberations are guided by climate simulations carried out
by the Intergovernmental Panel on Climate Change. The simulations focus
on a gloomy scenario in which it is assumed that humans will burn coal,
oil and gas at faster and faster rates.
This gloomy scenario leads to an additional forcing of three watts
in the next 50 years. Such a forcing will almost surely lead to
increases in climate extremes and a rising sea level.
Some increase in human climate forcing is inevitable. Fossil fuels
are our primary source of energy. Because of the energy infrastructure,
it requires decades to phase in new technologies that may produce less
carbon dioxide.
However, we recently suggested a scenario that reduces the human
forcing to only one watt in the next 50 years. This would yield a more
moderate climate change, allowing time to understand climate change
better and develop technologies and strategies to deal with it.
There are two elements in this commonsense solution to global
warming. First we must stop the growth of air pollution. This would
eliminate any added climate forcing by constituents other than carbon
dioxide. Second we must burn fossil fuels, and thus emit carbon
dioxide, no faster than we do today. That means that growing energy
needs must be met by increased efficiencies in current uses and by
introducing technologies that produce little or no carbon dioxide.
Both elements are achievable but unlikely to happen by accident.
Technologies that reduce air pollution have to be applied. Annual
growth of carbon dioxide emissions, which has already slowed from 4 to
1 percent per year, must be slowed a bit further to zero growth or a
small decrease.
Many actions could reduce both air pollution and carbon dioxide
emissions. We need to develop clean fuels and renewable energy sources,
and remove barriers to energy efficiency. Improved technology, perhaps
including fuel cells and hydrogen power, can help reverse the trend to
greater gas-guzzling vehicles. Utility profits should be designed to
reward improved efficiency and decreased air pollution.
Improved energy efficiency, cleaner uses of fossil fuels and
development of renewable energy sources will have multiple benefits. In
addition to slowing the growth of carbon dioxide, this will create
jobs, improve economic competitiveness, reduce reliance on foreign
sources of energy and improve public health.
Fine particles in air pollution, including soot, sulfates and
organic aerosols, penetrate human tissue deeply, causing respiratory
and cardiac problems. A recent study found that air pollution in
France, Austria and Switzerland alone accounts for 500,000 asthma
attacks and 40,000 deaths per year. Air pollution in developing
countries, such as India and China, is even more severe.
International cooperation is needed, because emissions circulate
worldwide. But benefits of progress, in climate stabilization and
health, will be similarly widespread. Required cooperation, including
technology transfer, can include incentives and economic opportunities
for all parties.
The commonsense approach is to move forward by attacking air
pollution, improving energy efficiency and developing renewable energy
sources. This approach is economically sound and has collateral
benefits. It should provide a meeting ground for persons from a wide
spectrum of political viewpoints, all of whom wish to preserve the
environment.
______
Responses to Written Questions Submitted by Hon. John McCain
to Dr. Richard S. Lindzen
Question 1. Your written statement refers to the limitations of
computer models. In two recently released studies, computer models
showed that the ocean warming that has been measured over the last
half-century is exactly what would he expected from the amount
greenhouse gases that have been emitted into the atmosphere. Tim
Barnett of Scripps Institution of Oceanography is quoted as saying
``This will make it much harder for naysayers to dismiss predictions
from climate models.'' Would you comment on these recent reports?
Answer. The arguments in both papers are fundamentally circular as
have been all attribution claims so far. What both papers show is that
in response to rising surface temperatures of the past 50 years or so,
there has been an increase in ocean heat content. Nothing controversial
here. The emphasis of Levitus et al on the quantity of heat in the
ocean is simply a statement that the heat capacity of the ocean is
high; this is the reason for the ocean delay. Again no surprise. The
claim that the observation confirms an anthropogenic cause is arrived
at by looking at climate models which stimulate the observed surface
temperature history by considering the joint effects of increasing C02
and aerosols. The argument goes that if models can stimulate the
surface temperature, and if observations show then deep ocean heat
content responds to surface temperature, then deep ocean heat content
is responding to anthropogenic forcing. However, the aerosol forcing
(which is crucial to stimulations) is so uncertain that it constitutes
in essence an adjustable parameter (or parameters)which can be adjusted
to produce a fit. The arguments of Levitus et al and Barnett et al then
boil down to a peculiar assertion that if one can adust models to fit
observations, the models must be right. Not exactly normative science.
That said, Barnett et al do mention some important things in
passing. One was the role of the `regime change' in the 1970's. This
may be the real origin of temperature increase over the past 30+ years.
The radiosonde data shows a very sharp increase in tropospheric
temperature around 1976, with the surface temperature catching up over
the following ten years (ocean delay again). This may be the reason for
discrepancy between the satellite MSU data and surface data: the
satellite data begins in 1979, after the atmospheric temperature rise
occurred. As Barnett et al mention, the models don't show the regime
change, and, therefore, the temperature rise they produce by adjusting
aerosol forcing is likely due to the wrong reason. A second, was the
comment that the coupled model they used was rather insensitive to
anthropogenic forcing. This is important for the following reason: for
sensitive models, the ratio of surface temperature to radiative forcing
at the surface is high (this is the meaning of sensitivity), and low
radiative forcing will cause the ocean to take longer to accumulate a
given amount of heat. Relatively rapid heating of the deep ocean
generally implies low climate sensitivity. In a paper by myself and
Giannitsis in the Journal of Geophysical Research about 3 years ago, we
looked at the observed response to volcanic sequences in order to
estimate climate sensitivity: the range 0.3-1 .2C for a doubling of
CO2 appeared most likely (We are following the conventional
practice of expressing sensitivity in terms of the response to doubling
CO2). More recently, at the meeting of European Geophysical
Society a couple of weeks ago, we did the same for the surface response
to regime change--and with the same result. Barnett et al really can't
do the same since they don't know the actual forcing.
Which brings me to the final point: although both papers claim to
have made an attribution (spuriously as far as I can tell), neither
claims to have established any sensitivity, and it is the question of
climate sensitivity that is crucial. Attribution without determining
sensitivity is a fairly abstract exercise with no practical implication
per se.
Finally, it should be pointed out that when these two papers
compared observations with model outputs, the agreement was not
particularly good.
Question 2. On the IPCC process, you have stated the vast majority
of the participants played no role in preparing the summary, were not
asked for agreement. Can you elaborate on this statement?
Answer. The IPCC directorate chooses the coordinating lead authors
for each chapter. There were 13 chapters in the Working Group I report.
Then a team about 15-30 lead authors are assembled for each chapter,
and finally another 40-50 contributing authors are chosen for each
chapter. (The numbers are approximate) Each 2-5 pages has about 2-3
lead authors responsible for their preparation with assistance from
contributing authors. Only the lead authors, however, attend the
meetings where their pages are prepared and reviewed. The meetings are
held around the world. For Working Group I, the meetings were in Paris,
Arusha in Tanzania, Auckland in New Zealand, and Victoria in British
Columbia. Although each lead author may comment on the whole chapter,
in practice, the lead authors generally concern themselves with the
pages they are expert in. After the chapters are completed (in the case
of Working Group I, this happened in August 2000), the coordinating
lead authors prepare a draft of the Summary, which is then studied by
the directorate as well as representatives from government, industry
and NGOs who proceed to rewrite the summary. This was done in Shanghai
in January 2001 for the Working Group I report. The resulting Summary
for Policymakers is not subject to approval by any of the authors.
Moreover, the directorate reserves the right to modify the chapters in
order to make them consistent with the summary. This is done with the
assistance of the coordinating lead authors. The text is not issued
until months after the Policymakers Summary.
Question 3. You have mentioned that the preparation of the report
was subject to pressure. You said that you personally witness co-
authors being forced to use their green'' credentials in defense of
their statements. Can you explain these ``green'' credentials?
In the sections on water vapor of Chapter 7 (Physics of Climate),
there were three lead authors (myself, Herve Letreut of France, and Ray
Pierrehumbert from the University of Chicago). Although Letreut is a
modeler and Pierrehumbert is a Sierra Club activist, and both wanted to
stress that the models might be right with respect to the crucial water
vapor feedback, we all agreed that the relevant physics should be
briefly reviewed with errors from previous IPCC reports corrected, and
that the potential problems be explained. When, the writeup failed to
include the traditional bromides of the first and second assessments,
the coordinating lead author, Thomas Stocker of Switzerland, who knew
nothing about the water vapor feedback, insisted that the pages be
rewritten to produce what was expected, and accused the three of us of
being unduly influenced by my allegedly contrarian and suspect views.
However, I had intentionally stayed out of the writing, and Herve and
Ray were forced to explain that they were actively pro-environmental
and supportive of global warming: they were only trying to tell the
truth. The scene was truly pathetic, and was witnessed by others.
Question 4. Background: Last year I introduced a bill, titled
``International Climate Change Science Commission Act'', to established
an International scientific commission to assess changes in global
climate patterns and to conduct scientific studies and analysis for
other nations. Given your experience with the IPCC, are you
recommending that the US and other countries rely upon another
scientific body such as the International commission that I proposed
last year?
Answer. I am not familiar with your bill. However, I am not sure
how the US would go about creating an international commission.
Certainly, it might be possible to create such a commission without a
tie to any negotiations, and a permanence that would be independent of
`crisis' and a charge that included understanding, monitoring, and
eventual forecasting of climate change regardless of its cause.
Question 5. You have stated that if we view Kyoto as an insurance
policy, it is a policy where the premium appears to exceed the
potential damages, and where the coverage extends to only a small
fraction of the potential damages. In your opinion, what type of
damages would not be covered?
Answer. If one considers most warming scenarios, and carefully
estimates the costs (viz Questions 2 from Sen. Kerry), they are at
worst comparable to the estimated costs of Kyoto, while Kyoto will, at
best, help us to avoid only a small fraction of the projected warming.
______
Response to Written Questions Submitted by Hon. John Kerry
to Dr. Richard S. Lindzen
Question 1. You have stated repeatedly and with some certainty that
a doubling of carbon dioxide in the atmosphere will produce a warming
of 1 degree Celsius at most. The IPCC has expressed far greater
uncertainty in its estimate of the warming impact of a doubling of
atmospheric carbon dioxide, offering a range of 1.5 to 5.8 degrees
Celsius. On what do you base your conclusion and why do you make that
conclusion with such confidence that you don `t suggest a range of
warming?
Answer. In my written testimony, I mentioned that the response to
double CO2 alone, without feedbacks from clouds and water
vapor, would produce about 1C warming. This is what virtually everyone
involved gets. I also mentioned that higher values resulted from
positive water vapor and cloud feedbacks in the models which have never
been confirmed in the observations. Indeed the wide range of model
results (which for a doubling of CO2 remain in the range
l.5-4C which is what was given in the 1979 Charney Report of the NRC)
results largely from the erratic behavior of clouds in the models. The
IPCC range is based on the range of results produced by current models
plus uncertainties in emissions scenarios with the highest value based
on a scenario which more than doubles CO2. In recent papers
(including one in preparation), we have sought observational estimates
of sensitivity and feedbacks, and have pretty much narrowed things to a
range of 0.3 to 1.2C which represents (in percentage terms) as great an
uncertainty as the IPCC model range of results. In a paper by myself
and Constantine Giannitsis, we looked at the temporal response to
volcanic eruptions which provides a direct measurement of sensitivity.
In another paper by myself, Ming-Dah Chou, and Arthur Hou, we used data
to estimate a negative cloud feedback completely absent from models
which essentially cancels model positive feedback--even if the latter
were correct, which seems unlikely.
Question 2. You argue that warming observed in recent decades
``represents what is on the whole a beneficial pattern.'' You have also
suggested that future warming may have beneficial impacts on the whole.
What specific imnpacts do you view as beneficial and what impacts do
you view as harmful in drawing that conclusion? What nations will
benefit the most from warming? What nations will benefit the least or
be harmed by warming?
Answer. With respect to my remark in the testimony, ``that warming
is likely to be concentrated in winters and at night . This is an
empirical result based on data from the past century. It represents
what is on the whole a beneficial pattern,'' the answer is fairly
obvious: longer growing seasons, less frost, fewer cold related deaths,
lower heating bills, less likelihood of older citizens moving to the
moving to the sun-belt. In addition, there are the benefits from
CO2 fertilization: greater agricultural productivity with
less need for water. The dangers are more speculative. Some endangered
species may be stressed further, and some changes in preferred
agricultural crops may be disadvantageous. Most scenarios of a
catastrophic nature, refer to storminess, sea level rise, droughts,
floods, etc., but these are even considered by the IPCC to be
speculative since observational evidence is very weak, and in the case
of extra tropical storminess, and variability, theory suggests the
opposite (as noted in my written testimony). Finally, although I
believe current models exaggerate the magnitude of warming. the
coupling of these models to economic models with due concern for the
detailed impact of climate change on specific sectors leads to a
positive impact of GDP in most of the world. The figure is taken from a
report by Prof. Robert Mendelsohri of Yale using Jim Hansen's model at
the Goddard Institute for Space Studies. It shows most of the Northern
Hemisphere benefitting, while parts of equatorial Africa and South Asia
suffering reduced GDP.
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