About seven-in-ten Americans (69%) say there’s solid evidence that the average temperature on earth has been getting warmer over the past few decades, according to a Pew Research Center survey conducted in March. That’s about as many as said so in 2008, although acceptance of the reality of global warming has risen and fallen considerably over that time span: from a high of 79% in July 2006 to a low of 57% in October 2009.
But opinions vary on what’s causing the planet’s mean temperature to rise. Four in ten (42%) said it was primarily due to human activity, such as burning fossil fuels, while 23% attributed the warming to natural variations in climate patterns. Another 27% said there was no solid evidence of any warming.
Although a solid majority of Americans believe the evidence of global warming is real, concern about it seems to have lessened over time. In a Pew Research survey from June 2006, about three-quarters of Americans said global warming was either a “very serious (41%) or “somewhat serious” (33%) problem.
But in the most recent survey, only 33% of Americans called global warming a very serious problem, and 32% said it was somewhat serious. Meanwhile, the percentage saying it was not a problem at all nearly doubled, from 11% in June 2006 to 20% in the most recent survey. Last year, 19% said it was not a problem at all.
In partisan terms, almost twice as many Democrats (87%) as Republicans (44%) say there’s solid evidence that the earth’s average temperature has been rising, and Democrats are three times as likely as Republicans to say that global warming is mainly caused by human activity (57% vs. 19%). Read more