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Surveys of scientists and scientific literature
97–98% of the most published climate researchers say humans are causing global warming.[106] In another study 97.4% of publishing specialists in climate change say that human activity is a significant contributing factor in changing mean global temperatures.[107]
Main article: Surveys of scientists' views on climate change
Various surveys have been conducted to evaluate scientific opinion on global warming. They have concluded that the majority of scientists support the idea of anthropogenic climate change.
In 2004, the geologist and historian of science Naomi Oreskes summarized a study of the scientific literature on climate change.[108] She analyzed 928 abstracts of papers from refereed scientific journals between 1993 and 2003 and concluded that there is a scientific consensus on the reality of anthropogenic climate change.
Oreskes divided the abstracts into six categories: explicit endorsement of the consensus position, evaluation of impacts, mitigation proposals, methods, paleoclimate analysis, and rejection of the consensus position. Seventy-five per cent of the abstracts were placed in the first three categories (either explicitly or implicitly accepting the consensus view); 25% dealt with methods or paleoclimate, thus taking no position on current anthropogenic climate change. 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."
In 2007, Harris Interactive surveyed 489 randomly selected members of either the American Meteorological Society or the American Geophysical Union for the Statistical Assessment Service (STATS) at George Mason University. The survey found 97% agreed that global temperatures have increased during the past 100 years; 84% say they personally believe human-induced warming is occurring, and 74% agree that "currently available scientific evidence" substantiates its occurrence. Only 5% believe that that human activity does not contribute to greenhouse warming; and 84% believe global climate change poses a moderate to very great danger.[109] [110]
Dennis Bray and Hans von Storch conducted a survey in August 2008 of 2058 climate scientists from 34 different countries.[111] 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%. No paper on climate change consensus based on this survey has been published yet (February 2010), but one on another subject has been published based on the survey.[112]
The survey was composed of 76 questions split into a number of sections. There were sections on the demographics of the respondents, their assessment of the state of climate science, how good the science is, climate change impacts, adaptation and mitigation, their opinion of the IPCC, and how well climate science was being communicated to the public. Most of the answers were on a scale from 1 to 7 from 'not at all' to 'very much'.
To the question "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 67.1% said they very much agreed, 26.7% agreed to some large extent, 6.2% said to they agreed to some small extent (2–4), none said they did not agree at all. 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.
A poll performed by Peter Doran and Maggie Kendall Zimmerman at University of Illinois at Chicago received replies from 3,146 of the 10,257 polled Earth scientists. Results were analyzed globally and by specialization. 76 out of 79 climatologists 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. Among all respondents, 90% agreed that temperatures have risen compared to pre-1800 levels, and 82% agreed that humans significantly influence the global temperature. Economic geologists and meteorologists were among the biggest doubters, with only 47 percent and 64 percent, respectively, believing in significant human involvement. The authors summarised the findings:
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.[107]
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.[113]
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 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.[114][115
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