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The IPCC and its reports

In 1988, the United Nations and the World Meteorological Organization convened the Intergovernmental Panel on Climate Change (IPCC) in order “to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts,” according to the IPCC website. The IPCC does not conduct original research, although most of the members are active researchers, but instead surveys existing research and produces periodic assessment reports. These reports represent the breadth of current research, with careful attention to issues of certainty and confidence in results. The assertions made in these reports are ones on which there is broad consensus within the research community.

There are three groups (with changing membership) that work on these reports: Working Group I (The Physical Science Basis), Working Group II (Impacts, Adaptation, and Vulnerability), and Working Group III (Mitigation of Climate Change). They have published Assessment Reports (AR) in 1990, 1995, 2001, 2007, and the most recent (AR5) over the course of 2013 to 2014. Each AR consists primarily of three long, comprehensive documents produced by the working groups. In addition, each AR has a condensed Summary for Policymakers. Finally, there is a version of the AR that consists of a synthesis of the three working groups’ reports plus the Summary for Policymakers. This last document is the easiest version for members of the public to read, in terms of its length and depth. It discusses the scope and quality of evidence in support of all claims that it makes, and although it does not contain many literature citations, it does refer you to the individual AR5 Working Group reports, which contain much more expansive discussions of evidence and full literature citations. All IPCC documents can be found at their website.

We cite these documents as follows:

  • AR5 WG1 refers to the following document: IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.
  • AR5 WG2 refers to the following document: IPCC, 2014: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1132 pp.
  • AR5 WG3 refers to the following document: IPCC, 2014: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1435 pp.
  • AR5 Synthesis Report refers to the following document: IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp.

The following passages are taken from the AR5 Synthesis Report:

Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. (pg. 2)


Anthropogenic greenhouse gas emissions have increased since the pre-industrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century. (pg. 4)


Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks. (pg. 8)


Climate change will amplify existing risks and create new risks for natural and human systems. Risks are unevenly distributed and are generally greater for disadvantaged people and communities in all countries at all levels of development. (pg. 13)


Many aspects of climate change and associated impacts will continue for centuries, even if anthropogenic emissions of greenhouse gases are stopped. The risks of abrupt or irreversible changes increase as the magnitude of the warming increases. (pg. 16)


The main conclusions that appear in AR5 fall under the following broad headings:

  • Trend: Global warming is occurring and is changing the climate.
  • Attribution: The primary cause of the current warming is human activity, particularly the burning of fossil fuels.
  • Impact: Unchecked climate change will have varied negative impacts for people, ecosystems, and biodiversity.
  • Mitigation: Lowering the risks associated with climate change requires significant and sustained reductions in GHG emissions, and the longer we wait to address this, the greater the risks and costs we incur.


Books and articles

  • The Thinking Person’s Guide to Climate Change, by Robert Henson, American Meteorological Society, 2014.
  • The Global Warming Reader:  A Century of Writing About Climate Change, edited by Bill McKibben, Penguin Books, 2012
  • The Oxford Handbook of Climate Change and Society, edited by Dryzek, Norgaard, and Schlosberg, Oxford University Press, 2011
  • Merchants of Doubt:  How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming, by Naomi Oreskes and Erik M. Conway, Bloomsbury Press, 2010
  • The Hockey Stick and the Climate Wars:  Dispatches from the Front Lines, by Michael E. Mann, Columbia University Press, 2012
  • Climate Literacy:  The Essential Principles of Climate Science (A Guide for Individuals and Communities)  This 18 page pdf was developed by NOAA, AAAS, NASA, and numerous other governmental and non-governmental institutions.

Web resources on the science of global warming and climate change

  •  The NASA Earth Observatory site has wonderful satellite views of the earth and its natural systems.  There are several pages on global warming and climate, including the following:
  •  This page at the Center for Climate and Energy Science (C2ES) website has quick, accessible explanations of some of the main scientific points, plus a link to a Kids’ Corner.
  •  This Climate Change FAQ at the Encyclopedia of Earth has accessible, detailed explanations of technical aspects of climate, including radiative forcing and models, and addresses some skeptical claims.  It does not have literature citations, but does give references to other online sources.
  • This is the FAQ list for the IPCC’s AR5 Working Group 1, on the physical science basis (trend, attribution, and impact).  Explanations are of intermediate difficulty, more detailed than at other sites listed here.

Web resources that address skeptical claims

Web resources that investigate the credibility of skeptics and skeptical organizations

Climate Education Initiative

  • Fenton 204 State University of New York at Fredonia Fredonia, NY 14063

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