1970s ("NCA4", USGCRP, 2017) includes charts illustrating how human factors, especially accumulation in the atmosphere of greenhouse gases, are the predominant cause of observed global warming. largely matching the survey's "moderate global warming" scenario.
1980s In 1989, David H. Slade had surveyed 21 climate scientists, of whom 17 had expressed "a strong belief" in "the reality of a significant climate change". In 1996,
Dennis Bray and
Hans von Storch, a pair of researchers at the Helmholtz Research Centre's Institute for Coastal Research, sent a
questionnaire over mail to 1000 climate scientists in Germany, the United States and Canada. 40% responded, and the results subsequently published in the
Bulletin of the American Meteorological Society in 1999. On a scale of 1 out of 7, where
higher numbers indicated greater
disagreement, "global warming is already underway" had a mean rating of 3.4, and "global warming will occur in the future" had an even greater agreement of 2.6 Surveyed scientists had less confidence in the accuracy of contemporary
climate models, rating their ability to make "reasonable predictions" 10 years out at 4.8, and 5.2 for 100-year predictions: however, they consistently rejected the notion that there was too much uncertainty to justify taking immediate action, with a mean 5.6 out of 7 rating. In fact, they usually agreed there was substantial uncertainty about how strongly the impacts will affect society, and that many changes would likely be necessary to adapt. Similarly, there was a 72% to 20% split in favour of describing the IPCC reports as accurate, and a 15% to 80% rejection of the thesis that "there is enough uncertainty about the phenomenon of global warming that there is no need for immediate policy decisions."
2005–2009 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, publishing the results in April 2008. 97% of the scientists surveyed agreed that global temperatures had increased during the past 100 years, and only 5% believed that human activity does not contribute to greenhouse warming. 84% said they personally believed human-induced warming was occurring, and 74% agreed that "currently available scientific evidence" substantiated its occurrence. 56% described the study of global climate change as a mature science and 39% as an emerging science. When asked about the likely severity of effects of climate change over the next 50–100 years, 41% said they could be described as catastrophic; 44% thought the effects would be moderately dangerous while about 13% thought there was relatively little danger. The third Bray and von Storch survey was also conducted in 2008, with the results published in 2010. It used the same methodology as their two previous surveys, with a similar number of sections and also asking to rate responses on a 1-to-7 scale (i.e. from 'not at all' to 'very much'), but it had also introduced web links with respondent-specific unique identifiers to eliminate multiple responses. 2058 climate scientists from 34 countries were surveyed, and a total of 373 responses were received (response rate of 18.2%). To the question "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 67.1% said they very much agreed (7), 26.7% agreed to some large extent (6), 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. Similarly, 34.6% had very much agreed that climate change "poses a very serious and dangerous threat to humanity" and 27.6% agreed to a large extent, while only 1.1% did not agree at all. At the same time, the respondents had strongly rejected the concept of intentionally presenting the most extreme possibilities in the hope of mobilizing the public, with around 73% disagreeing (1–3), 12.5% unsure and 14.5% agreeing in any way (5–7). Only 1.6% had agreed very much, while 27.2% did not agree at all, even as they overwhelmingly agreed (84% vs. 4%) that the scientists who do this are the most likely to be listened to by journalists. The respondents have generally expressed high confidence in the IPCC reports, with 63.5% agreeing that they estimated the impacts of temperature change exactly right (4 on the scale), and only 1.4% responding that they had strongly underestimated and 2.5% that they had strongly overestimated those impacts (1 and 7 on a scale.) On sea level rise, 51.4% thought the reports were exactly right, and only about 16% thought it was overestimated in any way (5–7), while the remaining third believed it was underestimated (1–3). Subsequent IPCC reports had been forced to regularly increase their estimates of future sea level rise, largely in response to newer research on the
ice sheets of Greenland and
Antarctica. In 2009,
Peter Doran and Maggie Kendall Zimmerman at
University of Illinois at Chicago polled 10,257
earth scientists from various specialities and received replies from 3,146. 79 respondents were
climatologists who had published over half of their peer-reviewed research on the subject of climate change, and 76 of them agreed that mean global temperatures had risen compared to pre-1800s levels, with 75 describing human activity as a significant factor. 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. In summary, Doran and Zimmerman wrote:
2010–2014 A 2010 paper in the
Proceedings of the National Academy of Sciences of the United States of America reviewed publication and citation data for 1,372 climate researchers, 908 of whom had authored 20 or more publications on climate, and found that (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. In October 2011, researchers from George Mason University analyzed the results of a survey of 998 actively working scientists from the American Geophysical Union, the American Meteorological Society, or listed in the 23rd edition of
American Men and Women of Science, 489 of whom had returned completed questionnaires. 97% of respondents had agreed that global temperatures have risen over the past century. 84% agreed that "human-induced greenhouse warming is now occurring," 5% disagreed, and 12% didn't know. When asked what they regard as "the likely effects of global climate change in the next 50 to 100 years," on a scale of 1 to 10, from Trivial to Catastrophic: 13% of respondents replied 1 to 3 (trivial/mild), 44% replied 4 to 7 (moderate), 41% replied 8 to 10 (severe/catastrophic), and 2% didn't know. This was a follow-up to an analysis looking at 2,258 peer-reviewed articles published between November 2012 and December 2013, which revealed that only one of the 9,136 authors rejected anthropogenic global warming. Dennis Bray and Hans von Storch had conducted their fourth survey in 2013, publishing its results the following year. 283 scientists had responded: 185 (65.4%) had been working in climate science for over 15 years, and only 19 (6.7%) had 0 to 5 years of experience. It had the same methodology as the third survey, ranking responses on a 1-to-7 scale and similar responses to the same questions: i.e., when asked, "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 74.7% said they very much agreed (7), 2.9% were "neutral" (4), and only 2.1% were 1–3 on the scale. 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?", 43% had very much agreed, 28.5% agreeing to a large extent (6), 16.6% to a small extent (2–4), and 2.5% did not agree at all (1). 41.8% had very much agreed that climate change "poses a very serious and dangerous threat to humanity" and 23.2% agreed to a large extent, while 3.5% did not agree at all. A new question asked respondents to attribute a
percentage of recent warming to anthropogenic causes: 73.3% of scientists attributed 70–100%, while only 1.5% said there was zero human role. surveyed 1,868 climate scientists. They found that, consistent with other research, the level of agreement on anthropogenic causation correlated with expertise – 90% of those surveyed with more than 10 peer-reviewed papers related to climate (just under half of survey respondents) explicitly agreed that greenhouse gases were the main cause of global warming. They included researchers on mitigation and adaptation in their surveys in addition to physical climate scientists, leading to a slightly lower level of consensus compared to previous studies.
2015–2019 . In other ways, it had replicated the methodology of the previous surveys, with most responses ranked on a 1-to-7 scale. There were over 600 complete responses: 291 (45.2%) had been working in climate science for over 15 years, while 79 (12.3%) had 0 to 5 years of experience. When asked "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 79.3% said they very much agreed (7), 1.2% were "neutral" (4), and only 2.1% were 1–3 on the scale. 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?", 47.7% had very much agreed, 26% agreeing to a large extent (6), 9.8% to a small extent (2–4), and 1.9% did not agree at all (1). 46% had very much agreed that climate change "poses a very serious and dangerous threat to humanity" and 26% agreed to a large extent, while 2.2% did not agree at all. 75.8% said that the level of uncertainty in climate science had decreased since 1996, while 13.6% said it had increased. 75.7% said that the level of risk associated with climate change had increased considerably since 1996, while 5% said it had decreased. In 2017, James L. Powell analyzed five surveys of the peer-reviewed literature from 1991 to 2015, and found that they amounted to a combined 54,195 articles, few of which had outright rejected anthropogenic climate change, resulting in an average consensus of 99.94%. == See also ==