When it comes to climate change, deforestation and toxic waste, the assumption has been that conservative views on these topics are intractable. But new research from the University of California, Berkeley, suggests that such viewpoints can be changed after all, when the messages about the need to be better stewards of the land are couched in terms of fending off threats to the "purity" and "sanctity" of Earth and our bodies.

A UC Berkeley study has found that while people who identified themselves as conservatives tend to be less concerned about the environment than their liberal counterparts, their motivation increased significantly when they read articles that stressed the need to "protect the purity of the environment" and were shown such repellant images as a person drinking dirty water, a forest filled with garbage, and a city under a cloud of smog.

Published in the online issue of the journal Psychological Science, the findings indicate that reframing pro-environmental rhetoric according to values that resonate strongly with conservatives can reduce partisan polarization on ecological matters.

"These findings offer the prospect of pro-environmental persuasion across party lines," said Robb Willer, a UC Berkeley social psychologist and coauthor of the study. "Reaching out to conservatives in a respectful and persuasive way is critical, because large numbers of Americans will need to support significant environment reforms if we are going to deal effectively with climate change, in particular."

Researchers conducted a content analysis of more than 200 op-eds published in such newspapers as The New York Times, USA Today and The Wall Street Journal, and found the pro-environmental arguments were most often pitched in terms of moral obligations to care about the natural environment and protect it from harm, a theme that resonates more powerfully with liberals, they added, than with conservatives.

They hypothesized that conservatives would be more responsive to environmental arguments focused on such principles as purity, patriotism and reverence for a higher authority. In their study, the authors specifically tested the effectiveness of arguments for protecting the purity of the environment. They said the results suggest they were on the right track:

"When individuals view protecting the environment as a moral issue, they are more likely to recycle and support government legislation to curb carbon emissions," said Matthew Feinberg, a postdoctoral fellow in psychology at Stanford University and lead author of the study which he conducted while at UC Berkeley.

Scientific consensus on the existence of warming global land and ocean temperatures - attributed in large part to human activities that produce greenhouse gas emissions - continues to grow and influence public opinion, especially with such extreme weather events as Hurricane Sandy. A recent Rasmussen poll reported that 68 percent of Americans view climate change as a "serious problem," compared to a 2010 Gallup poll in which 48 percent of Americans said they thought global warming was exaggerated.

In the first experiment, 187 men and women recruited via several U.S. Craigslist websites rated their political ideology on a scale of "extremely liberal" to "extremely conservative." They then rated the morality of such activities as recycling a water bottle versus throwing it in the garbage. The results of that experiment, and a similar one conducted on 476 college undergraduates, showed that liberals are more prone to viewing sustainability as a moral issue than are conservatives.

Next, researchers conducted a content analysis of pro-environmental videos on YouTube and more than 200 op-eds in national newspapers, sorting them under the themes of "harm/care," which they expected to resonate more with liberals, and "purity/sanctity," which they predicted would appeal more to conservatives. They found that most pro-environmental messages leaned strongly toward liberal moral concerns.

In the last experiment, 308 men and women, again recruited via Craigslist, were randomly assigned to read one of three articles. The harm/care-themed article described the destruction wreaked on the environment by humans and pitched protection of the environment as a moral obligation. Images accompanying the text were of a forest with tree stumps, a barren coral reef and drought-cracked land, which are more typical of the visuals promoted by pro-environmental groups.

The purity/sanctity-themed article stressed how pollution has contaminated Earth and people's bodies, and argued for cleaning up and purifying the environment. To enhance those themes and elicit disgust, the accompanying images showed a person drinking filthy water, a city under a cloud of pollution and a forest full of garbage. The neutral article talked about the history of neckties.

Participants were then asked to rate how strongly they felt certain emotions, including disgust, in response to what they'd read. Next, they reported how strongly they agreed or disagreed with such statements as "It is important to protect the environment," "I would support government legislation aimed at protecting the environment" and 'I believe humans are causing global warming."

Overall, the study found that the purity-themed message inspired conservatives to feel higher levels of disgust, which in turn increased their support for protecting the environment.