The latest Gallup poll on climate
"Record percentages of Americans are concerned about global warming, believe it is occurring, consider it a serious threat and say it is caused by human activity. All of these perceptions are up significantly from 2015," reports Gallup (March 14, 2017).
Specifically, asked, "And from what you have heard or read, do you believe increases in the Earth's temperature over the last century are due more to – [ROTATED: the effects of pollution from human activities (or) natural changes in the environment that are not due to human activities]," 68% of respondents identified human activities as responsible for increases in the Earth's temperature, while 29% chose natural causes and 3% ventured no opinion. (The bracketed interpolation is Gallup's.)
Asked, "Just your impression, which one of the following statements do you think is most accurate – most scientists believe that global warming is occurring, most scientists believe that global warming is NOT occurring, or most scientists are unsure about whether global warming is occurring or not," 71% of respondents said that most scientists believe that global warming is occurring, while 5% said that most scientists believe that it is not occurring, 22% were unsure, and 2% ventured no opinion.
The poll (PDF) was conducted by telephone March 1-5, 2017, with a random sample of 1018 adults in the United States; the sample was weighted to match national demographics. The margin of sampling error was +/-4 percentage points at the 95% confidence level.