Despite the growing scientific consensus that global warming is real, Americans have become increasingly polarized on the environmental problem, according to a first-of-its-kind study led by a Michigan State University researcher.

The gap between Democrats and Republicans who believe global warming is happening increased 30 percent between 2001 and 2010  a "depressing" trend that's essentially keeping meaningful national energy policies from being considered, argues sociologist Aaron M. McCright.

"Instead of a public debate about different policies to deal with global warming, a significant percentage of the American public is still debating the science," said McCright, MSU associate professor and primary investigator on the study. "As a result, we're failing to significantly address one of the most serious problems of our time."

The study is featured in the spring issue of the research journal Sociological Quarterly, online now.

McCright and Riley E. Dunlap of Oklahoma State University analyzed 10 years of data from Gallup's environmental poll, making the study the first of its kind to use multiple years of data. The Gallup poll, conducted annually, consists of a nationally representative telephone survey of at least 1,000 people.

According to the MSU-led study, people on the right of the political spectrum increasingly deny the existence of global warming, while people on the left generally believe in global warming more now than they did 10 years ago. Among other things, the study found:



Of those who identify as Republicans, about 49 percent said in the 2001 Gallup survey that they believe the effects of global warming have already begun  a number that dropped to 29 percent in 2010. Meanwhile, the percentage of Democrats who believe global warming has already begun increased from about 60 in 2001 to 70 in 2010. All told, the gap between these "believers" in the two parties increased from 11 percent in 2001 to 41 percent in 2010.



A similar trend held for people who identify as either conservative or liberal. When it came to believing that global warming has already begun, the gap between conservatives and liberals increased from about 18 percent in 2001 to 44 percent in 2010.



Among liberals and Democrats, having a college degree increases the likelihood of reporting beliefs consistent with the scientific consensus. Yet, among conservatives and Republicans, having a college degree often decreases the likelihood of reporting such beliefs.

According to McCright, these results are consistent with the prevailing theory that explains how political polarization occurs in the general public. "In the last few decades political elites have become polarized on climate change. This has driven the political divide on this topic within the American public, as regular citizens have taken cues from ideological and party leaders they trust."

McCright said the process has been magnified over the past decade by the emergence of media outlets where citizens can seek out news and ideas that reinforce their values and beliefs. He said citizens at either end of the political spectrum can get daily information  albeit very different information  on global warming that further strengthens their opposing beliefs about what is real.

"Unfortunately, this is not a recipe for promoting a civil, science-based discussion on this very serious environmental problem," McCright said. "Like with the national discussion on health care, we don't even agree on what the basic facts are."

This political polarization on climate change is not likely to go away in the near future, he added.

"Many Republican Party leaders have moved further to the right since the 2008 presidential election. We've also seen attacks on climate science by Tea Party activists. It seems like climate change denial has become something of a litmus test for Republican candidates," McCright said.

"This continued elite polarization on climate change means that the general public will likely remain politically divided on climate change for a while."

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