Human activities - including adding to the concentrations of carbon
dioxide and other greenhouse gases in the atmosphere - are "altering
the Earth's climate," according to a new position statement by
the American Geophysical Union. The increased levels of atmospheric
carbon dioxide are likely to "remain in the atmosphere for hundreds
to thousands of years," the statement continues, and "it is
virtually certain that increasing atmospheric concentrations of carbon
dioxide and other greenhouse gases will cause global surface climate
to be warmer."
The statement, "Human Impacts on Climate," was endorsed unanimously
by the Council of AGU this month, and released on December 16 with a
series of briefings to the media and congressional staffers. The release
of the AGU statement comes less than two months after an historic vote
in the Senate on legislation to regulate carbon dioxide and other greenhouse
gases (see FYI
#152). Although the bill, "The Climate Stewardship Act
of 2003," was defeated this time around, its key sponsors, Senators
Joseph Lieberman (D-CT) and John McCain (R-AZ) vowed not to give up
the fight. Also, within the past month, the Department of Energy released
an inventory of the federal government's current climate change technology
activities, and a report on technology options for the future. Both
documents are available on DOE's climate change technology program web
site at http://www.climatetechnology.gov/
.
The AGU statement is an attempt to communicate to the public and policymakers
the current state of scientific understanding about human influences
on the Earth's climate, AGU president Robert Dickinson explained. The
new statement replaces one first issued in December 1998 and, according
to Marvin Geller of SUNY Stony Brook, is intended to reflect the scientific
progress made in the intervening time. While the new statement does
not reveal any "startling" new research results, he said,
it summarizes the peer-reviewed literature and is consistent with studies
by the Intergovernmental Panel on Climate Change and the National Research
Council.
Geller summarized the main points of the statement: In order to explain
the observed temperature record, climate models must include human activity;
increasing atmospheric concentrations of greenhouse gases are "virtually
certain" to cause warming of the global surface climate; predictions
about the global-scale impacts of warming are more certain than predictions
about regional impacts; while more can be learned from additional research,
short-term actions can help mitigate the situation without major societal
disruptions; AGU believes no single threshold can be defined above which
interference is "dangerous;" and peer-reviewed science should
be the basis for all policy decisions.
A number of congressional staffers sought an AGU opinion on what climate
change policies should be implemented, but Geller explained that it
was not the society's role to recommend policy; many other socio-political
factors outside the expertise of the AGU membership needed to be considered
in formulating a policy. But he said that policymakers could use the
statement to assess the scientific basis for policy alternatives: "If
people are using science to make policy arguments, and it differs much
from what you read here, be careful!" he said.
The representatives of AGU were also asked how long the U.S. could
safely wait to implement policies on climate change. Geller pointed
out that some scientists believe the Earth is already experiencing dangerous
impacts. "It's highly unlikely you'll ever get perfect certainty,"
he said; political decisions will have to be made "in the presence
of scientific uncertainties." Geller cautioned that the consequences
of decisions made now will still be felt "hundreds of years from
now," and Dickinson added that not taking action "is a policy."
The AGU statement will be reproduced in its entirety in FYI
#164.
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