Americans' support for government action on global warming remains high but has dropped during the past two years, according to a new survey by Stanford researchers in collaboration with Ipsos Public Affairs. Political rhetoric and cooler-than-average weather appear to have influenced the shift, but economics doesn't appear to have played a role.

The survey directed by Jon Krosnick, a senior fellow at the Stanford Woods Institute for the Environment, shows that support for a range of policies intended to reduce future climate change dropped by an average of 5 percentage points per year between 2010 and 2012.

In a 2010 Stanford survey, more than three-quarters of respondents expressed support for mandating more efficient and less polluting cars, appliances, homes, offices and power plants.

Nearly 90 percent of respondents favored federal tax breaks to spur companies to produce more electricity from water, wind and solar energy. On average, 72 percent of respondents supported government action on climate change in 2010. By 2012, that support had dropped to 62 percent.

The drop was concentrated among Americans who distrust climate scientists, even more so among such people who identify themselves as Republicans. Americans who do not trust climate science were especially aware of and influenced by recent shifts in world temperature, and 2011 was tied for the coolest of the last 11 years.

Krosnick pointed out that during the recent campaign, all but one Republican presidential candidate expressed doubt about global warming, and some urged no government action to address the issue.

Rick Santorum described belief in climate change as a "pseudo-religion," while Ron Paul called it a "hoax." Mitt Romney, the apparent Republican nominee, has said, "I can tell you the right course for America with regard to energy policy is to focus on job creation and not global warming."

The Stanford-Ipsos study found no evidence that the decline in public support for government action was concentrated among respondents who lived in states struggling the most economically.

The study found that, overall, the majority of Americans continue to support many specific government actions to mitigate global warming's effect. However, most Americans remain opposed to consumer taxes intended to decrease public use of electricity and gasoline.