As world leaders meet this week and next at a historic climate change summit in Paris, a new study by Michigan State University environmental scientists suggests opponents of climate change appear to be winning the war of words.

The research, funded by the National Science Foundation, finds that climate-change advocates are largely failing to influence public opinion. Climate-change foes, on the other hand, are successfully changing people's minds - Republicans and Democrats alike - with messages denying the existence of global warming.

"This is the first experiment of its kind to examine the influence of the denial messages on American adults," said Aaron M. McCright, a sociologist and lead investigator on the study. "Until now, most people just assumed climate change deniers were having an influence on public opinion. Our experiment confirms this."

The findings come as leaders from 150 nations attempt to forge a treaty to reduce greenhouse gas emissions. During a speech Monday at the Paris summit, President Barack Obama said the "growing threat of climate change could define the contours of this century more dramatically than any other."

Nearly 1,600 U.S. adults took part in the MSU study. Participants read fabricated news articles about climate change and then completed a survey gauging their beliefs on the issue. The articles contained either positive or negative real-world messages about climate change, or both.

The positive messages framed the topic of climate change around one of four major issues: economic opportunity, national security, Christian stewardship and public health. According to the article addressing public health, for example:

"Medical experts argue that dealing with climate change will improve our public health by reducing the likelihood of extreme weather events, reducing air quality and allergen problems, and limiting the spread of pests that carry infectious diseases."

In half of the articles, participants were presented a negative message that read, in part: "However, most conservative leaders and Republican politicians believe that so-called climate change is vastly exaggerated by environmentalists, liberal scientists seeking government funding for their research and Democratic politicians who want to regulate business."

Surprisingly, none of the four major positive messages changed participants' core beliefs about climate change. Further, when the negative messages were presented, people were more apt to doubt the existence of climate change - and this was true of both conservatives and liberals.

"That's the power of the denial message," said McCright, associate professor in MSU's Lyman Briggs College and Department of Sociology. "It's extremely difficult to change people's minds on climate change, in part because they are entrenched in their views."

The study appears online in the journal Topics in Cognitive Science. McCright's co-authors are fellow MSU researchers Meghan Charters, Katherine Dentzman and Thomas Dietz.