(Bars show the difference between each decade’s average temperature and the overall average for 1901 to 2000. The far right bar includes data for 2001-2012. Source: U.S. National Climate Assessment).
Our most recent survey, conducted in April, 2014, finds that by more than a three-to-one margin, more Americans think global warming is happening than think it is not. Currently, 64% of Americans think global is happening, a number that has been relatively stable over the past three years.
Our survey also shows that Americans’ certainty that the Earth is warming has increased over the past three years. Currently, of those who think global warming is happening, nearly two in three (62%) say they are either extremely (30%) or very (32%) sure that it is. Three years ago, in May 2011, fewer (54%) were as sure. And over the same three-year period, those who think global warming is not happening have become substantially less sure of their position (from 52% in May 2011, to 41% today).
These findings are notable in light of the fact that the survey was conducted shortly after much of the country experienced a particularly cold winter, including the “polar vortex”, suggesting that Americans’ growing certainty that global warming is happening was relatively unaffected by their recent experience of extreme cold weather.