The chairman of the Intergovernmental Panel on Climate
Change acknowledges it has been a rough few months for his
organization. But, he argues, no amount of obfuscation and attacks
by conspiracy theorists will alter the basic facts - global warming
is real and intensifying.

by rajendra k. pachauri

Yale e360 - Science thrives on
debate. Only by challenging scientific findings do we expose weak
arguments and substantiate strong ones. But the process relies on
the debate being devoid of political taint and grounded in sound
scientific knowledge. Sadly, that has not been the case in the
recent barrage of criticism leveled against climate science.

The readers of Yale Environment 360 are by now familiar with
recent questioning by some of the validity of the widely accepted
science of climate change. The release of emails stolen from the
University of East Anglia was used just prior to the Copenhagen
Climate Summit to project an unflattering portrayal of climate
scientists in general and to voice allegations that climate science
was deeply flawed.

(It is significant that the U.K. House of Commons Science and
Technology Committee last month issued a report essentially
exonerating the researchers involved of any ill intent or
wrongdoing, as did an independent panel established by the
university.) This episode was followed by accusations that the
Intergovernmental Panel on Climate Change (IPCC), which I chair,
had exaggerated the severity of climate change.

Though some of the criticism has been thoughtful and was
welcomed by the IPCC, much of it relied on unsubstantiated
conspiracy theories and gross mischaracterizations that would be
laughable were they not intended to create a bias in public
perceptions on this critical issue. Certainly, in any

To call climate science a ‘hoax’ amounts to a tremendous
disservice to science and to humanity.human endeavor there is
always room for improvement, and that is particularly true of
enhancing the level of thoroughness in searching for new knowledge.
In this context, the IPCC has listened and learned from the more
reasoned criticism voiced recently. As I will explain later in this
article, the panel is also taking action to refine its procedures
in response to fair and objective criticism. But to call climate
science a “hoax,” as some fringe critics have done, amounts to a
tremendous disservice to science and to humanity as a whole.

Preparing Assessment Reports

Before responding to the criticism about the IPCC, I believe it
is important to describe how the panel functions. Only by
understanding how the IPCC prepares its reports can one put recent
developments into perspective.

The IPCC’s primary work entails collecting and assessing
published material on climate science and assembling it into
Assessment Reports (ARs) that are issued every five to six years.
These reports provide assessments on scientific, technical, and
socio-economic factors, which can provide the basis for making
rational policy decisions. The IPCC makes no policy recommendations
of its own.

All the scientists who work on IPCC assessments devote their
time voluntarily and receive no compensation. Yet their work is
unprecedented in scale; it is the world’s most comprehensive source
of climate change information. The latest assessment, AR4,
completed in 2007, had more than 450 lead authors who worked during
the course of several years to complete the report; their efforts
were supplemented by about 800 contributing authors and some 2,500
expert reviewers.

At each successive stage of drafting, the report was carefully
reviewed. A total of about 90,000 comments were produced during the
review process. The authors considered and reacted to each of those
comments. By the time it was completed, AR4 cited approximately
18,000 peer-reviewed publications. It also included a limited
amount of gray (or non-peer-reviewed) literature in cases where
peer-reviewed literature was unavailable. (For example, there is
often no peer-reviewed literature on impacts of climate change,
both current and projected, in many developing countries.)

The IPCC has a duty to correct or clarify any errors
that may slip into reports of this magnitude.

AR4 has been criticized for exaggerating the severity of climate
change. On the other hand, many regard the report as too
conservative and an understatement of the impacts of climate
change. This is due in part to the fact that preparing an
assessment report takes several years. For instance, AR4 was based
on scientific studies completed before January 2006, and did not
include later studies that may show accelerated melting of the
Greenland ice sheet and indications that sea levels may rise even
higher than previously projected. These and other published
material will be assessed in the AR5, which is scheduled to be
completed in 2014.

With the enormous increase in published literature on various
aspects of climate change, the lode of knowledge that the authors
of AR5 will have to unearth will increase substantially, making the
task ahead even more daunting. There is now much higher awareness
worldwide of the scientific realities of climate change. There is
also a much higher expectation of infallibility in all that the
IPCC does, particularly since the panel received the Nobel Peace
Prize in 2007.

IPCC procedures are robust and rigorous, but they can always be
improved. Upholding exacting standards is a responsibility and a
sacred trust that IPCC authors - and I - accept with the utmost
respect and sincerity. It is our duty to correct or clarify the
inevitable oversights and errors that may slip into reports of this
magnitude and complexity.

With this in mind, I would like to provide a response to some
issues that have given rise to recent controversy.

Himalayan Glaciers

AR4 stated that the Himalayan glaciers could melt by 2035. This
figure was incorrect and unfortunately based on a single
unsubstantiated source. When this error came to light, the IPCC
expressed its regret and noted it on its website. The error was
contained in a single sentence and in one graphic representation
out of AR4’s nearly 3,000 pages.

It did not appear in any of the IPCC summaries relied on by
policymakers. In those summaries, the language states: “Glacier
melt in the Himalayas is projected to increase flooding, and rock
avalanches from destabilized slopes, and to affect water resources
within the next two to three decades. This will be followed by
decreased river flows as the glaciers recede.” This statement
remains valid, as does the fact that widespread loss of glacial
mass and reduction in snow cover will accelerate throughout the
21st century largely as a result of human activities that are
warming our Earth’s atmosphere.

Amazon Rainforest

The IPCC was accused of exaggerating the extent to which the
Amazon rainforest could be damaged by a decrease in rainfall. The
paragraph in question correctly stated: “By mid-century, increases
in temperature and associated decreases in soil water are projected
to lead to gradual replacement of tropical forest by savanna in
eastern Amazonia. Semi-arid vegetation will tend to be replaced by
arid-land vegetation.”

This was a classic case in which the controversy was initiated
not by scientists but by the mainstream media, which badly
distorted the facts. Blogs and other articles argued incorrectly
that a report, the “Global Review of Forest Fires,” should not have
been cited as a reference, because it was published by two
non-governmental organizations. But the paragraph in question
accurately presented results in the literature it cited. It was a
small part of a long, well-referenced discussion of Amazonian risk.
Although the “Global Review of Forest Fires” was not a
peer-reviewed document, it nevertheless was an important
compilation, assembling information from more than 100 sources,
including peer-reviewed scientific papers and reports from
governments and non-governmental organizations, as well as news
articles.

This was a classic case in which controversy
was initiated not by scientists but by the media.

On March 18, 18 respected rainforest scientists from Brazil, the
U.S., and the U.K. issued a lengthy statement reaffirming the
IPCC’s conclusion that up to 40 percent of the Amazon rainforest is
at risk because of climate change. Their statement can found
online.

African Agriculture

Another alleged exaggeration of AR4 was that climate change
could reduce crop yields in parts of Africa by up to 50 percent.
The only concern here was that in condensing the material from the
underlying Working Group II Summary for Policymakers for the
Synthesis Reports, the important qualifying phrase “by climate
variability and change” was omitted from a statement that read:
“Agricultural production, including access to food, in many African
countries is projected to be severely compromised.” This is no way
diminished or altered the scientific basis or the policy relevance
of the statement included in the synthesis report.

Many of the IPCC’s conclusions about impacts in various regions
of the world include the effect of climate variability, not just
the effect of climate change. In the full underlying reports, this
caveat was fully explained. This is another area where a small
issue of the wording of one sentence - on a subject that was dealt
with in a balanced way throughout the report - has been blown out
of proportion.

Major findings of the AR4

None of these issues diminish in any way the major findings of
the AR4, which presented voluminous, well-documented evidence of
the steady warming of the planet. For instance, 11 of the last 12
years covered in the report (1995-2006) were found to rank among
the 12 warmest years in the instrumental record of global surface
temperature since 1850. The 100-year linear temperature increase
for the period 1906-2005 was 0.74 degrees C. The temperature
increase was found to be widespread around the globe and greater at
higher northern latitudes. For instance, the Arctic region has been
warming at twice the rate of the global average. The AR4 also
documented the steady disappearance of Arctic sea ice, the retreat
of glaciers worldwide, and changes in the timing of seasons around
the globe - all convincing evidence of a warming world.

In addition, the report found that sea level increases were
consistent with warming, having risen since 1961 at an average rate
of 1.8 millimeters per year and since 1993 at 3.1 millimeters per
year, due to contribution from thermal expansion of the oceans, and
melting glaciers and ice sheets.

As for the projected impacts of climate change, several findings
are of significance to policymakers. Based on current knowledge and
trends, approximately 20 to 30 percent of plant and animal species
assessed so far are likely to be at increased risk of extinction if
increases in global average temperatures exceed 1.5 to 2.5 degrees
C. At lower latitudes, especially in seasonally dry and tropical
regions, crop productivity is projected to decrease with even small
levels of temperature increase (1-2 degrees C), which would
increase the risk of hunger. At the same time, coastal areas are
projected to be exposed to increasing risks, including coastal
erosion due to climate change and sea level rise. This effect will
be exacerbated by human-induced pressure on coastal areas.

None of these issues diminish the major findings,
which presented voluminous evidence of warming.

The health status of millions of people is projected to be
affected, for example, through increases in malnutrition, diseases,
and injury due to extreme weather events. It is reasonable to
project increased frequency of cardio-respiratory disease due to
high concentrations of ground level ozone in urban areas related to
climate change. Infectious diseases will likely spread as the
climate warms. The availability of water would also be impacted
significantly by climate change, with exacerbation of current
stresses on water resources.

Many adverse impacts can be reduced, delayed, or avoided by
mitigation, and mitigation measures and investments over the next
two to three decades will help stabilize levels of greenhouse gases
in the atmosphere. The AR4 has determined that the cost of
stringent mitigation is actually quite modest and is not likely to
exceed 3 percent of global GDP in 2030, if the world targets a path
of emissions that would stabilize global temperatures at a rise of
between 2.0-2.4 degrees C. Mitigation measures also carry benefits
such as higher energy security, lower levels of air pollution, and
job creation.

The IPCC’s findings about
already-observed changes, projections for the future, and
mitigation options provide a robust framework for decision
making.

The Road Ahead

I stand firmly behind the principle that the IPCC must do all
that is humanly possible to eliminate errors or any statements that
might be easily misinterpreted. It is for this reason that the
IPCC, in tandem with the Secretary General of the United Nations,
has requested the Inter-Academy Council to carry out a review of
IPCC procedures and practices so that the work of the panel meets
the highest possible standards and its assessments maintain a high
level of credibility and reliability. The review will include the
IPCC’s use of gray literature.

The public is entitled to demand clear and
credible knowledge on which decisions can be based.

The scientific community, as embodied in the work of the IPCC,
is ready to meet in all respects the increasing and exacting
expectations of policymakers and the public. Given the importance
and the serious implications of any actions related to climate
change, the public and political leaders are entitled to demand
clear and credible knowledge on which decisions can be based.

In a field such as this, perfect certainty about the future will
remain elusive. But we have adequate certainty today based on the
findings of the AR4, which give us a rationale for taking action
and meeting the challenge of climate change. What actions are in
the best interests of society should be the subject of a spirited,
intense, and science-based global debate.

I sincerely believe that this period, difficult though it has
been, will have a positive outcome. Climate science will be the
better for it. The public will be better informed by it. And the
scientific community will learn that it has to interact with and be
accountable to the public.

We are living in an information age when any comments or
criticism warrant an instant explanation or response. The IPCC has
to develop the capability to do this. Gone are the days when an
important subject like climate change could remain the preserve of
ivory tower scientific institutions. Knowledge in this field is of
critical relevance to society and will become increasingly
so.



Though the controversy - and the misinformation surrounding it -
may appear to have weakened support for climate science, I believe
this will be short lived. With controversy comes discussion, and
with discussion comes understanding. History is replete with
examples of how politics temporarily trumped science, but the truth
eventually triumphed.



Let’s hope it wins out in time for world leaders to take
action.

ABOUT THE AUTHOR

Rajendra K. Pachauri is chairman of the Intergovernmental Panel
on Climate Change, for which he accepted the Nobel Peace Prize in
2007. Since 2001, he has served as director general of The Energy
and Resources Institute (TERI), an India-based research
organization focused on issues related to energy, environment and
sustainable development. He is the author of more than 100 academic
articles and 23 books and is director of the Yale Climate and
Energy Institute.