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The Intergovernmental Panel on Climate Change (IPCC) emerged following the success of international diplomatic efforts to curb ozone depletion. Scientific discoveries in the mid-1980s quickly led to the Montreal Protocol, the global agreement that banned several ozone-depleting chemicals. The agreement showed that the United States and other nations worldwide were capable of responding together to meet an emerging global environmental threat.
In 1988, The World Meteorological Organization (WMO) and the United Nations Environmental Programme (UNEP) established the IPCC. It assesses available knowledge on climate change, including the physical science, environmental and societal impacts, and options for mitigation and adaptation. The IPCC also serves as a source of information guiding the U.N.’s Framework Convention on Climate Change. The U.N. framework has been signed by 192 nations, including the United States, in Rio de Janeiro in 1992. The Kyoto Protocol was the first effort to implement the framework. Another global agreement is slated for discussion in December 2009.
IPCC participants include researchers and government representatives. The IPCC does not conduct its own research; instead, it enlists hundreds of scientists around the world to review thousands of studies and synthesize the most important findings. This lengthy process includes meetings among the expert authors on each topic to reach scientific consensus on which findings can be reported with confidence. Each resulting report chapter is then given a peer review by yet more topic experts who were not involved in writing the chapter.
The resulting IPCC assessment reports have been issued in 1990, 1996, 2001, and 2007. The assessments are also reviewed by additional scientists on behalf of governments around the world and then formally accepted by those governments. The diplomats themselves review the brief Summaries for Policymakers that accompany each major section of the final report. It’s important to note that the diplomats have a say in how each Summary for Policymakers is worded, but the scientists have the last word on what is said.
The number of scientists involved, the extensive review process, and the participation of nearly all governments around the world means that IPCC findings carry great weight as benchmark statements of the state of climate science.
Because so many scientists and governments are involved, IPCC conclusions are often quite conservative, focusing on the most solidly accepted aspects of climate research. For example, the 2007 IPCC report estimates that global average sea level will rise by 7.2-23.6 inches (18-59 cm) by 2100 compared to the 1980-1999 average. In settling on this range, the IPCC excluded the contribution from dynamic melting of the Greenland and Antarctic ice sheets because this added effect cannot yet be accurately projected, even though many scientists believe it could be substantial.
More Information: IPCC Assessment reports
Principles Governing IPCC Work