Intergovernmental Panel on Climate Change

Introduction

The Intergovernmental Panel on Climate Change (IPCC) is a scientific committee established in 1988 by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO), both arms of the United Nations. The purpose of the IPCC is to pool, evaluate, and summarize the current state of scientific knowledge about all aspects of climate change, especially human-caused climate change, and to evaluate policies related to climate change. Experts from more than 130 countries were participating in the IPCC as of 2008. The IPCC does not conduct original research, but is a forum in which the consensus view of the world’s climate and meteorology communities can be forged in open debate. Its reports have been influential in the formation of world public opinion about the reality and causes of climate change.

Historical Background and Scientific Foundations

The theory that Earth is kept warm by the heat-capturing effect of carbon dioxide and other gases was first proposed by Swedish chemist Svante Arrhenius (1859–1927) in 1896. Starting in the 1950s, some scientists, notably Canadian physicist Gilbert Plass (1921–2004), began to propose that human-caused increases in greenhouse-gas concentrations, especially of carbon dioxide and methane, might cause the world’s climate to warm. In 1979, the WMO, the United Nations’ organization for the study of weather and other aspects of earth science, organized a World Climate Conference, the first of its kind. Scientists at the conference agreed that possible human-caused climate warming was a concern.

In 1985, a United Nations scientific conference in Austria also concluded that significant human-caused global warming might be occurring or occur in the future. The tenth congress of the WMO recommended an international, scientific assessment of climate change. The new group, the IPCC, was authorized by the Executive Council of the WMO and the Governing Council of the UNEP in 1988. Its facilities are in Geneva, Switzerland.

The work of the IPCC is primarily to prepare reports on climate issues after sifting and debating scientific evidence from peer-reviewed scientific sources. A peer-reviewed source is an article or book that is subjected to criticism by some of the author’s fellow scientists (that is, his or her peers or equals) before publication. Peer review is the scientific community’s method of screening out faulty work.

Experts are appointed to the IPCC by each participating government. Such scientists work as volunteers. IPCC reports are prepared following a complex process in which authors prepare a draft that is peer-reviewed, revised, reviewed by experts and the participating governments, and revised again to produce a final draft that is again reviewed by participating governments. The IPCC’s reports are some of the most intensively peer-reviewed summaries of scientific knowledge ever produced.

Impacts and Issues

The IPCC has produced special reports on the storage of carbon dioxide, the ozone layer, and other climate topics. Its most influential products have been its four Assessment Reports on global climate change in 1990, 1995, 2001, and 2007. Responsibility for each of these reports was divided among three working groups. The first group reported on the physical scientific basis of climate-change knowledge. This included weather observations from surface and satellite sources; paleoclimate data from ice cores, ocean-sediment cores, and other sources; observations of changes in ecosystems such as forests; and the results of computer calculations. The second working group reported on the impacts of climate change on agriculture, forestry, ecosystems, water resources, human settlements, and oceans. The third reported on possible adaptation and vulnerability to climate change. All three sub-reports emphasized areas of uncertainty and ignorance.

The IPCC’s fourth Assessment Reports, titled Climate Change 2007, were released in 2007. New data were available to the scientists drafting this report, including more information about ancient climate and a widened range of carefully tested computer models. The scientific uncertainties of earlier years were reduced. In its 2007 report, the IPCC stated that “warming of the climate system is unequivocal” and that “most (>50%) of the observed increase in globally averaged temperatures since the mid-20th century is very likely (confidence level >90%) due to the observed increase in anthropogenic (human-caused) greenhouse-gas concentrations.”

The IPCC’s 2007 report has been both praised and criticized. Among the critics are those who doubt greenhouse warming and argue that global warming is either not real or is merely a natural process, not human-caused. Many of these critics are not scientists, or are not experts in climate or weather science, though a few are qualified scientists. The great majority of climate and weather scientists agreed, as of 2007, that the IPCC’s basic conclusions were valid.

On the other hand, the 2007 IPCC report has also been criticized for being too conservative in discussing climate change and its effects. Possible reasons for IPCC over-optimism include the report’s exclusion of data collected after the end of 2005 (data collected since that time show faster melting of ice in Greenland and part of Antarctica). Another possible reason is the influence over the IPCC report-preparation process by governments—such as those of the United States, China, and Saudi Arabia—which have so far refused to agree to binding changes in their industrial, agricultural, and other climate-related practices.

In 2007, the work of the IPCC, along with that of former U.S. Vice President Al Gore, was acknowledged with the Nobel Peace Prize. According to the Nobel Committee, they were chosen "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change.” Following the announcement, some wondered why the IPCC and Gore had won the “peace” prize, rather than one in the sciences. In a press release, the Nobel committee explained its selection, noting that in awarding the

WORDS TO KNOW

ANTHROPOGENIC: Made by humans or resulting from human activities.

GREENHOUSE GAS: A gas whose accumulation in the atmosphere increases heat retention.

ICE CORE: A cylindrical section of ice removed from a glacier or ice sheet in order to study climate patterns of the past.

PALEOCLIMATE: The climate of a given period of time in the geologic past.

PEER REVIEW: The standard process in science for reducing the chances that faulty or fraudulent claims will be published in scientific journals. Before publication of an article, scientists with expertise in the article’s subject area review the manuscript, usually anonymously, and make criticisms that may lead to revision or rejection of the article.

prize as it did, it was “highlighting the link… between the risk of accelerating climate change and the risk of violent conflict and wars.” The committee observed that climate change could impact living conditions throughout the world, leading various peoples to migrate to less-impacted areas. As Earth’s resources become more limited, increased violence and conflict may result.

See Also Climate Change; Global Warming; IPCC 2007 Report

BIBLIOGRAPHY

Books

Committee on the Science of Climate Change, National Academy of Sciences. Climate Change Science: An Analysis of Some Key Questions. Washington, DC: National Academies Press, 2001.

Metz, B., et al, eds. Climate Change 2007: Mitigation of Climate Change: Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. New York: Cambridge University Press, 2007.

Parry, M. L., et al, eds. Climate Change 2007: Impacts, Adaptation and Vulnerability: Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. New York: Cambridge University Press, 2007.

Solomon, S., et al, eds. Climate Change 2007: The Physical Science Basis: Contribution of Working Group I to the Fourth Assessment Report of the

Intergovernmental Panel on Climate Change. New York: Cambridge University Press, 2007.

Web Sites

Intergovernmental Panel on Climate Change (IPCC). “16 Years of Scientific Assessment in Support of the Climate Convention.” December 2004. http://www.ipcc.ch/pdf/10th-anniversary/anniversary-brochure.pdf (accessed March 25, 2008).

Nobel Foundation. “The Nobel Peace Prize 2007.” October 2007. http://nobelprize.org/nobel_prizes/peace/laureates/2007/ (accessed March 25, 2008).

Larry Gilman

IN CONTEXT: FRANK AND STARK WARNINGS

“Continued greenhouse-gas emissions at or above current rates would cause further warming and induce many changes in the global climate system during the 21st century that would very likely be larger than those observed during the 20th century.”

…“It is very likely that hot extremes, heat waves and heavy precipitation events will continue to become more frequent.”

SOURCE: Solomon, S., et al, eds. “IPCC, 2007: Summary for Policymakers.” In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. New York: Cambridge University Press, 2007.