Surveys of scientists' views on climate change – with a focus on human-caused or anthropogenic global warming (AGW) – have been undertaken since the 1990s. A 2016 paper (which was co-authored by Naomi Oreskes, Peter Doran, William Anderegg, Bart Verheggen, Ed Maibach, J. Stuart Carlton and John Cook, and which was based on a half a dozen independent studies by the authors) concluded that "the finding of 97% consensus [that humans are causing recent global warming] in published climate research is robust and consistent with other surveys of climate scientists and peer-reviewed studies." A 2019 study found scientific consensus to be at 100%, and a 2021 study found that consensus exceeded 99%.
2020s
Myers et al., 2021
Krista Myers led a paper which surveyed 2780 Earth scientists. Depending on expertise, between 91% (all scientists) to 100% (climate scientists with high levels of expertise, 20+ papers published) agreed human activity is causing climate change. Among the total group of climate scientists, 98.7% agreed. The agreement was lowest among scientists who chose Economic Geology as one of their fields of research (84%).
Lynas et al., 2021
In 2021, Mark Lynas et al assessed studies published between 2012 and 2020. They found over 80,000 studies. They analysed a random subset of 3000. Four of these were skeptical of the human cause of climate change, 845 were endorsing the human cause perspective at different levels, and 1869 were indifferent to the question. The authors estimated the proportion of papers not skeptical of the human cause as 99.85% (95% confidence limit 99.62%–99.96%). Excluding papers which took no position on the human cause led to an estimate of the proportion of consensus papers as 99.53% (95% confidence limit 98.80%–99.87%). They confirmed their numbers by explicitly looking for alternative hypotheses in the entire dataset, which resulted in 28 papers.
2010s
Powell, 2019
In 2019, James L. Powell, a former member of the National Science Board, analysed titles of peer-reviewed studies published in the first seven months of 2019 and found not a single study disagreed with the consensus view. When the titles implied uncertainty about the cause of climate change, the abstracts or the article in its entirety were examined. The total amount of articles found via Web of Science was 11,602.
Verheggen et al., 2014
In 2014, Bart Verheggen of the Netherlands Environmental Assessment Agency 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.
Powell, 2013
James L. Powell 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 (<0.2%) rejected anthropogenic global warming. 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.
John Cook et al., 2013
Cook et al. examined 11,944 abstracts from the peer-reviewed scientific literature from 1991 to 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 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.
In their discussion of the results, the authors said that the large proportion of abstracts that state no position on AGW is as expected in a consensus situation, as anticipated in a chapter published in 2007, 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."