The Scientific Consensus
The scientific community has reached a strong consensus that global temperatures are rising rapidly as a direct result of billions of tons of carbon dioxide and other greenhouse gas emissions from human-made sources.
Satellites See Unprecedented Greenland Ice Sheet Surface Melt
The world’s leading scientific body focused on climate change is the Intergovernmental Panel on Climate Change (IPCC), formed in 1988 by the World Meteorological Organization and the United Nations Environment Programme. The IPCC, made up of hundreds of scientists with relevant expertise from throughout the world, evaluates the state of peer-reviewed1 and published climate research every few years. The IPCC first expressed the scientific consensus that climate change is real and caused by humans in 2001. The group of international experts came to the same conclusion in the 2007 IPCC Fourth Assessment Report, stating that all available evidence pointed to a more than 90% probability that human activities are warming the planet.2
The Intergovernmental Panel on Climate Change (IPCC) released the Summary for Policymakers for the Fifth Assessment in September 2013. This report finds that evidence of warming is “unequivocal” and that it is “extremely likely” that human influence has been the dominant cause of that warming. The latest observations illustrate the changes that are already underway. The observations show: increasing atmospheric carbon dioxide concentrations, rising air and ocean water temperatures, declines in the extent of arctic ice, and declining pH in ocean waters.3
To view more information about how climate change has changed over time, and to “plot” your own times series graph using data from 1895 through 2012, please visit the NOAA Plot Time Series Website maintained by the National Climatic Data Center's Climate Services and Monitoring Division.
Every major scientific organization in the United States with relevant expertise has confirmed the IPCC’s conclusion, including the National Academy of Sciences,4 the American Meteorological Society,5 the American Geophysical Union,6 and the American Association for the Advancement of Science.7 The list of international scientific organizations affirming the worldwide consensus on climate change is even longer (see List of Organizations). Several studies have shown that about 97% of climate scientists actively doing research agree that climate change is happening and is human-caused.8,9 A study published in May, 2013 examined 11,944 climate abstracts from 1991–2011 in peer-reviewed scientific literature and affirmed that 97.1% of these scientists endorsed the consensus position that humans are causing global warming.10
Does this mean that no scientific questions remain about climate change? Of course not. Scientists continue their efforts to better understand the many complex issues associated with climate change, including the rate of warming in the future, the specific climate impacts local areas will face, and the future rate of ice melt and sea level rise. The basic, fundamental facts that climate change is occurring and its central cause is human-made emissions are no longer subject to meaningful scientific debate: climate change is real, it's caused by human activities, we are already seeing the effects, and our current path has put us on course for dire results in the not-too-distant future.
The US National Academy of Sciences and The Royal Society cordially invite you to join us for the release of “Climate Change: Evidence & Causes,” a new publication produced jointly by the two institutions. Written by a UK-US team of leading climate scientists and reviewed by climate scientists and others, the publication is intended as a brief, readable reference document for decision makers, policy makers, educators, and other individuals seeking authoritative information on the some of the questions that continue to be asked.
1: “Peer Review” is a process used by scientific and scholarly journals to ensure that the articles they publish represent the best scholarship available. When an article is submitted to a peer-reviewed journal, the editors send it out to the other experts in the same field (the author’s peers) for review of the article’s quality and relevance. Journals and publications that are not peer-reviewed rely only on the judgment of the editors, who are limited in number and may not have any relevant expertise.
2: IPCC 4th, Working Group I: The Physical Basis for Climate Change, Summary for Policy Makers at pp. 3, n. 7; 10.
3: IPCC 5th, Working Group I: The Physical Basis for Climate Change, Summary for Policy Makers at pp. 3, n. 7; 10.
4: See Joint Science Academies’ Statement: Global Response to Climate Change. June 7, 2005 (includes U.S. National Academy of Sciences).
5: See AMS, Climate Change – An Information Statement of the American Meteorological Society (Adopted by AMS Council on February 1, 2007) Bull. Amer. Met. Soc., 88.
6: See AGU, Humans Impact Climate, and the Scientific Community has the Responsibility to Educate and Communicate the Implications of Climate Change to the Public and Policy Makers. Reaffirmed February 2012.
7: See AAAS Board Statement on Climate Change. December 9, 2006.
8: Doran, PT and MK Zimmerman (2009). Examining the scientific consensus on climate change. Eos Trans American Geophysical Union. 90(3): p. 22.
9: Anderegg, WRL, JW Prall, J Harold, and SH Schneider (2010). Expert credibility in climate change. Proceedings of the National Academy of Sciences USA. 107: p. 12107-12109.
10: Quantifying the consensus on anthropogenic global warming in the scientific literature. http://iopscience.iop.org/1748-9326/8/2/024024/article