You’ve no doubt heard the statement made by politicians and others (maybe even some of your friends) that “97% of climate scientists agree that man-made global warming is real, and that it is caused mainly by human activity.” Is that statement true, and if so, where did it originate? The apparent source is an article by John Cook and co-authors (2013) that actually states that 97% of published articles (that they surveyed) on climate change over a 20 year period endorsed the view that the Earth is warming up, and that human emissions of greenhouse gases are mostly to blame. Since some of the papers were written by the same authors, it is difficult to leap to that 97% figure based on this sample. Not only that, many of the authors felt that the conclusions of their papers were misrepresented. After the results were challenged, someone calculated that only about 1.6% of the articles stated explicitly that man-made greenhouse gases caused at least 50% of global warming. 
The American Meteorological Society (AMS) recently completed a survey of its membership to learn more about their views on climate change. About 39% of the AMS members who responded consider themselves “climate scientists,” and the rest are mostly degreed scientists specializing in various atmospheric or technology disciplines. The results indicated that while the large majority (89%) of the more than 4,000 respondents believe that climate change is occurring, a little more than two-thirds (69%) believe that the changes are mostly or entirely due to human activity, while 14% think natural and man-made causes are about equal. A small but significant number believe that climate change is either completely due to natural causes (5%), isn’t happening at all (1%), or don’t know (6%).
Opinions in the AMS study on the extent to which future climate change can be averted if all nations agree to mitigation measures are also varied. Only 18% think a large portion of future changes can be prevented while many more think that a moderate (42%) or small (25%) additional amount of climate change can be averted.
In summary, while a majority of atmospheric scientists (including climate scientists) believe that human- caused warming is occurring, the percentage that believe that the majority of recent climate change is due to manmade causes is much less than 97%, and is probably more like two-thirds. Also, less than half believe that a significant portion of the expected warming can be prevented through global mitigation efforts.
- Cook, J. , D. Nuccitelli, S. Green, M. Richardson, B. Winkler, R. Painting, R. Way, P. Jacobs, and A. Skuce, 2013: Quantifying the consensus on global warming in the scientific literature. Environ. Research Letters, Vol. 8, 7 pages.
- Epstein, A., 2015: ‘97% of Climate Scientists Agree’ is 100% Wrong, Forbes /Energy and the Environment, Jan. 15, 2015
- Maibach, E., Perkins, D., Francis, Z., Myers, T., Englbom, A., 2016. A 2016 National Survey of American Meteorological Society Member Views on Climate Change: Initial Findings. George Mason University, Fairfax, VA: Center for Climate Change Communication