Sept. 27, 2013

NAS President Comments on Release of IPCC's Fifth Assessment Report

The Intergovernmental Panel on Climate Change (IPCC) announced today in Stockholm the release of the first part of its Fifth Assessment Report (AR5). Prepared by Working Group I, this portion of AR5 on the physical science basis of climate change will be available in full shortly; a Summary for Policymakers is available immediately.

"The release of AR5 is another significant milestone in the advancement of climate change science," said Ralph J. Cicerone, president of the U.S. National Academy of Sciences. "We express our gratitude to the hundreds of experts from around the world who volunteered to take part in this important scientific endeavor. The result of their combined expertise reinforces the evidence base and scientific consensus that human activity is causing climate change. Their critical review and synthesis of the latest models, measurements, observations, and other data give policymakers an important evidence base upon which to make decisions about how best to mitigate and adapt to climate change."

The IPCC was established in 1988 by the World Meteorological Organization and the United Nations Environment Programme. Its First Assessment Report in 1990 led to the United Nations Framework Convention on Climate Change, a treaty intended to limit greenhouse gas emissions, which President George H.W. Bush signed at the Rio Earth Summit in 1992.

Two more IPCC Working Groups on mitigation and adaptation are expected to issue their contributions to the Fifth Assessment Report in 2014.
The National Research Council, the operating arm of the National Academy of Sciences and National Academy of Engineering, has issued several reports on the causes of -- and potential responses to -- climate change. America's Climate Choices and other climate change resources from the National Research Council are available at