Is there a scientific consensus on global warming?
There is no consensus
The Petition Project features over 31,000 scientists signing the petition stating "There is no convincing scientific evidence that human release of carbon dioxide will, in the forseeable future, cause catastrophic heating of the Earth's atmosphere ...". (Petition Project)
What the science says...
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That humans are causing global warming is the position of the Academies of Science from 19 countries plus many scientific organizations that study climate science. More specifically, around 95% of active climate researchers actively publishing climate papers endorse the consensus position. |
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Scientists need to back up their opinions with research and data that survive the peer-review process. A survey of all peer-reviewed abstracts on the subject 'global climate change' published between 1993 and 2003 shows that not a single paper rejected the consensus position that global warming is man caused (Oreskes 2004). 75% of the papers agreed with the consensus position while 25% made no comment either way (focused on methods or paleoclimate analysis).
Subsequent research has confirmed this result. A survey of 3146 earth scientists asked the question "Do you think human activity is a significant contributing factor in changing mean global temperatures?" (Doran 2009). More than 90% of participants had Ph.D.s, and 7% had master’s degrees. Overall, 82% of the scientists answered yes. However, what are most interesting are responses compared to the level of expertise in climate science. Of scientists who were non-climatologists and didn't publish research, 77% answered yes. In contrast, 97.5% of climatologists who actively publish research on climate change responded yes. As the level of active research and specialization in climate science increases, so does agreement that humans are significantly changing global temperatures.

Figure 1: Response to the survey question "Do you think human activity is a significant contributing factor in changing mean global temperatures?" (Doran 2009) General public data come from a 2008 Gallup poll.
Most striking is the divide between expert climate scientists (97.4%) and the general public (58%). The paper concludes:
"It seems that the debate on the authenticity of global warming and the role played by human activity is largely nonexistent among those who understand the nuances and scientific basis of long-term climate processes. The challenge, rather, appears to be how to effectively communicate this fact to policy makers and to a public that continues to mistakenly perceive debate among scientists."
This overwhelming consensus among climate experts is confirmed by an independent study that surveys all climate scientists who have publicly signed declarations supporting or rejecting the consensus. They find between 97% to 98% of climate experts support the consensus (Anderegg 2010). Moreover, they examine the number of publications by each scientist as a measure of expertise in climate science. They find the average number of publications by unconvinced scientists (eg - skeptics) is around half the number by scientists convinced by the evidence. Not only is there a vast difference in the number of convinced versus unconvinced scientists, there is also a considerable gap in expertise between the two groups.

Figure 2: Distribution of the number of researchers convinced by the evidence of anthropogenic climate change and unconvinced by the evidence with a given number of total climate publications (Anderegg 2010).
Scientific organizations endorsing the consensus
The following scientific organizations endorse the consensus position that "most of the global warming in recent decades can be attributed to human activities":
- American Association for the Advancement of Science
- American Astronomical Society
- American Chemical Society
- American Geophysical Union
- American Institute of Physics
- American Meteorological Society
- American Physical Society
- Australian Meteorological and Oceanographic Society
- Australian Bureau of Meteorology and the CSIRO
- British Antarctic Survey
- Canadian Foundation for Climate and Atmospheric Sciences
- Canadian Meteorological and Oceanographic Society
- Environmental Protection Agency
- European Federation of Geologists
- European Geosciences Union
- European Physical Society
- Federation of American Scientists
- Federation of Australian Scientific and Technological Societies
- Geological Society of America
- Geological Society of Australia
- International Union for Quaternary Research (INQUA)
- International Union of Geodesy and Geophysics
- National Center for Atmospheric Research
- National Oceanic and Atmospheric Administration
- Royal Meteorological Society
- Royal Society of the UK
The Academies of Science from 19 different countries all endorse the consensus. 11 countries have signed a joint statement endorsing the consensus position:
- Academia Brasiliera de Ciencias (Brazil)
- Royal Society of Canada
- Chinese Academy of Sciences
- Academie des Sciences (France)
- Deutsche Akademie der Naturforscher Leopoldina (Germany)
- Indian National Science Academy
- Accademia dei Lincei (Italy)
- Science Council of Japan
- Russian Academy of Sciences
- Royal Society (United Kingdom)
- National Academy of Sciences (USA) (12 Mar 2009 news release)
A letter from 18 scientific organizations to US Congress states:
"Observations throughout the world make it clear that climate change is occurring, and rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver. These conclusions are based on multiple independent lines of evidence, and contrary assertions are inconsistent with an objective assessment of the vast body of peer-reviewed science."
The consensus is also endorsed by a Joint statement by the Network of African Science Academies (NASAC), including the following bodies:
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African Academy of Sciences
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Cameroon Academy of Sciences
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Ghana Academy of Arts and Sciences
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Kenya National Academy of Sciences
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Madagascar's National Academy of Arts, Letters and Sciences
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Nigerian Academy of Sciences
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l'Académie des Sciences et Techniques du Sénégal
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Uganda National Academy of Sciences
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Academy of Science of South Africa
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Tanzania Academy of Sciences
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Zimbabwe Academy of Sciences
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Zambia Academy of Sciences
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Sudan Academy of Sciences
Two other Academies of Sciences that endorse the consensus:
Last updated on 24 January 2012 by John Cook. View Archives
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