Summary of opinions from climate and earth scientists regarding climate change.
Just over 97% of published climate researchers say humans are causing most global warming.
of papers from refereed scientific journals between 1993 and 2003 and concluded that there is a scientific consensus on the reality of
. None of the abstracts disagreed with the consensus position, which the author found to be "remarkable". According to the report, "authors evaluating impacts, developing methods, or studying paleoclimatic change might believe that current climate change is natural. However, none of these papers argued that point."
. 97% of the scientists surveyed agreed that global temperatures had increased during the past 100 years; 84% said they personally believed human-induced warming was occurring, and 74% agreed that "currently available scientific evidence" substantiated its occurrence. 5% said they thought human activity did not contribute to greenhouse warming.
To the question "How convinced are you that most of recent or near future climate change is, or will be, a result of anthropogenic causes?" the responses were 34.6% very much agree, 48.9% agreeing to a large extent, 15.1% to a small extent, and 1.35% not agreeing at all.
received replies from 3,146 of the 10,257 polled Earth scientists. Results were analyzed globally and by specialization. 76 out of 79
who "listed climate science as their area of expertise and who also have published more than 50% of their recent peer-reviewed papers on the subject of climate change" believed that mean global temperatures had risen compared to pre-1800s levels. Seventy-five of 77 believed that human activity is a significant factor in changing mean global temperatures.
(PNAS) reviewed publication and citation data for 1,372 climate researchers and drew the following two conclusions:
(i) 97–98% of the climate researchers most actively publishing in the field support the tenets of ACC (Anthropogenic Climate Change) outlined by the Intergovernmental Panel on Climate Change, and (ii) the relative climate expertise and scientific prominence of the researchers unconvinced of ACC are substantially below that of the convinced researchers.
[118]
A 2013 paper in
Environmental Research Letters reviewed 11,944 abstracts of scientific papers matching "global warming" or "global climate change". They found 4,014 which discussed the cause of recent global warming, and of these 97.1% endorsed the consensus position.
[119]
James L. Powell, a former member of the
National Science Board and current executive director of the
National Physical Science Consortium, analyzed published research on global warming and climate change between 1991 and 2012 and found that of the 13,950 articles in peer-reviewed journals, only 24 rejected anthropogenic global warming.
[120] A follow-up analysis looking at 2,258 peer-reviewed climate articles with 9,136 authors published between November 2012 and December 2013 revealed that only one of the 9,136 authors rejected anthropogenic global warming.
[121]
SURVEYS OF SCIENTISTS VIEWS ON CLIMATE CHANGE
Bray and von Storch, 2008
Dennis Bray and
Hans von Storch conducted a survey in August 2008 of 2058 climate scientists from 34 different countries.
[11] A web link with a unique identifier was given to each respondent to eliminate multiple responses. A total of 373 responses were received giving an overall response rate of 18.2%.
In the section on climate change impacts, questions 20, 21 were relevant to scientific opinion on climate change. Question 21 "How convinced are you that most of recent or near future climate change is, or will be, a result of anthropogenic causes?" received 34.6% very much convinced, 48.9% being convinced to a large extent (5–6), 15.1% to a small extent (2–4), and 1.35% not convinced at all.
Anderegg, Prall, Harold, and Schneider, 2010
A 2010 paper in the
Proceedings of the National Academy of Sciences of the United States(PNAS) reviewed publication and citation data for 1,372 climate researchers and drew the following two conclusions:
(i) 97–98% of the climate researchers most actively publishing in the field support the tenets of ACC (Anthropogenic Climate Change) outlined by the Intergovernmental Panel on Climate Change, and (ii) the relative climate expertise and scientific prominence of the researchers unconvinced of ACC are substantially below that of the convinced researchers.
[14]
Farnsworth and Lichter, 2011
In an October 2011 paper published in the
International Journal of Public Opinion Research, researchers from George Mason University analyzed the results of a survey of 489 scientists working in academia, government, and industry. The scientists polled were members of the
American Geophysical Union or the
American Meteorological Society and listed in the 23rd edition of
American Men and Women of Science, a biographical reference work on leading American scientists. Of those surveyed, 97% agreed that global temperatures have risen over the past century. Moreover, 84% agreed that "human-induced greenhouse warming" is now occurring. Only 5% disagreed with the idea that human activity is a significant cause of global warming.
[17][18]
John Cook et al., 2013
Cook
et al. examined 11,944 abstracts from the peer-reviewed scientific literature from 1991–2011 that matched the topics 'global climate change' or 'global warming'. They found that, while 66.4% of them expressed no position on anthropogenic global warming (AGW), of those that did, 97.1% endorsed the consensus position that humans are contributing to global warming. They also invited authors to rate their own papers and found that, while only 35.5% rated their paper as expressing no position on AGW, 97.2% of the rest endorsed the consensus. In both cases the percentage of endorsements among papers expressing a position was marginally increasing over time. They concluded that the number of papers actually rejecting the consensus on AGW is a vanishingly small proportion of the published research.
[21] Also, a reply to the criticism of the study was published, saying: "[critic] believes that every paper discussing the impacts of climate change should be placed in the 'no opinion' category".
[22]
In their discussion of the results in 2007, the authors said that the large proportion of abstracts that state no position on AGW is as expected in a consensus situation,
[23] adding that "the fundamental science of AGW is no longer controversial among the publishing science community and the remaining debate in the field has moved on to other topics."
[21]
In
Science & Education in August 2013 David R. Legates (a professor of geography at the University of Delaware and former director of its Center for Climatic Research) and three coauthors reviewed the corpus used by Mr. Cook. In their assessment, "inspection of a claim by Cook et al. (Environ Res Lett 8:024024, 2013) of 97.1 % consensus, heavily relied upon by Bedford and Cook, shows just 0.3 % endorsement of the standard definition of consensus: that most warming since 1950 is anthropogenic."
However, as the paper took issue in the definition of consensus, the definition of consensus was split into several levels: In the end, of all the abstracts that took a position on the subject, 22.97 % and 72.50 % were found to take an explicit but unquantified endorsement position or an implicit endorsement position, respectively. The 0.3 % figure represents abstracts taking a position of "Actually endorsing the standard definition" of all the abstracts (1.02 % of all position-taking abstracts), where the "standard definition" was juxtaposed with an "unquantified definition" drawn from the 2013 Cook et al. paper as follows:
- The unquantified definition: ‘‘The consensus position that humans are causing global warming’’
- The standard definition: As stated in their introduction, that ‘‘human activity is very likely causing most of the current warming (anthropogenic global warming, or AGW)’’
Criticism was also subjected to the "arbitrary" disclusion of non-position-taking abstracts as well as other issues of definitions.
[24]
Craig Idso, Nicola Scafetta, Nir J. Shaviv and Nils-Axel Mörner, whose research questions the alleged consensus, also are cited as Climate scientists who assert that Cook misrepresented their work.
[25]
Powell, 2013
James L. Powell, a former member of the
National Science Board and current executive director of the
National Physical Science Consortium, analyzed published research on global warming and climate change between 1991 and 2012 and found that of the 13,950 articles in peer-reviewed journals, only 24 rejected anthropogenic global warming.
[26] This was a follow-up to an analysis looking at 2,258 peer-reviewed articles published between November 2012 and December 2013 revealed that only one of the 9,136 authors rejected anthropogenic global warming.
[27]