"Using responses from nearly 700 biophysical scientists," a new survey "finds that approximately 92 percent of them believe that human-caused climate change is really happening," according to the Washington Post (September 25, 2015), reporting on J. S. Carlton, Rebecca Perry-Hill, Matthew Huber, and Linda S. Prokopy's "The climate change consensus extends beyond climate scientists," published in Environmental Research Letters.
Asked "When compared with pre-1800's levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?" 93.6% of respondents indicated that they thought temperatures have risen, 2.1% indicated that they thought temperatures had remained relatively constant, 0.6% indicated that they thought temperatures had fallen, and 3.7% indicated they had no opinion or did not know.
When respondents who indicated that they thought that mean global temperatures have risen when compared to pre-1800s levels were asked, "Do you think human activity is a significant contributing factor in changing mean global temperatures?" 98.2% agreed. Multiplying 98.2% and 93.6%, Carlton and his colleagues concluded, "91.9% of scientists surveyed believed in anthropogenic climate change."
Presented with the proposition that climate science is a credible science, 78.79% of respondents strongly agreed, 15.30% moderately agreed, 3.03% slightly agreed, 1.06% were undecided, 0.61% slightly disagreed, 0.91% moderately disagreed, and 0.30% strongly disagreed. Carlton and his colleagues observed, "The average response to 'Climate science is a credible science' was 6.67 out of 7, indicating strong agreement."
The researchers concluded, "there is a general consensus among biophysical scientists across the United States that (1) climate change is occurring, (2) humans are contributing to it, and (3) climate science is a trustworthy, mature, and credible discipline. Scientists who continue to claim otherwise are operating outside of the consensus, not just of climate scientists, but also of scientists as a whole."
The survey was conducted among scientists at the twelve universities in the Big 10 conference. Two thousand scientists were randomly selected; 1868 were successfully contacted by e-mail and asked to take the survey; 698 responses were received (for a 37.4% response rate). Two versions of the survey, including or excluding "cultural values" questions, were used; there was no significant differences in response rate between the two versions.