Are celebrities helping or hurting the climate change conversation?

When President Obama and scientist Katharine Hayhoe took the stage at the White House's "South by South Lawn" event to discuss climate change on Monday, they were joined by a figure with no formal experience in politics or scientific research: actor Leonardo DiCaprio, who moderated the panel discussion.

Mr. DiCaprio, who produced the upcoming climate change documentary, "Before the Flood," set to air on the National Geographic channel later this month, is one of many celebrity advocates for environmental policy in recent years. Others include actor Mark Ruffalo, actress Jessica Alba, and singer-songwriter Pharrell Williams. 

Celebrities have a long track record of drawing media attention to important issues, experts say. But their influence on public opinion varies, depending on the celebrity and the audience at the receiving end of the message – and, in a political climate characterized by intense partisan polarization, such efforts can do more harm than good.

Most politicians welcome the attention of high-profile Hollywood figures to political causes, environmental or otherwise, "because of the high recognition that celebrities have," says Eric T. Kasper, an associate professor of political science at the University of Wisconsin-Eau Claire. He points out that many people feel a personal connection to stars, "because they have seen them countless times on television or in the movies."

"Their presence at this type of event can ... draw more media coverage, which may help to expose people to an issue for the first time," Dr. Kasper tells The Christian Science Monitor in an email. 

There's no question that the appearance of a Hollywood activist at a congressional hearing or White House event can generate additional coverage on the evening news or online media sites. But the degree to which celebrity advocates' messages influence public opinion is debatable, experts say, and depends on the individual situation. 

Research suggests that when people are exposed to a celebrity endorsing a cause, their main takeaway may not be the message itself but rather a desire to do more research on the issue themselves, says Mike Goodman, a professor of geography at the University of Reading in Britain: "They’re not necessarily picking up what these people say verbatim, but it gets them interested enough that they go out and look for further information." 

Celebrities tend to have more influence "among persons who don't already have a strong opinion on the issue," or "persons who are major fans of the celebrity's work," Kasper says. 

Many politicians and organizations embrace celebrity activists with the hope that their fame will provide them with a unique ability to cross the ever-deepening partisan divide, Professor Goodman notes. In these advocates' ideal world, celebrities could be "messengers that would soften the blow about issues around climate change."

However, he warns, star-powered publicity efforts can fall flat for many reasons, including timing, execution, and the particular celebrity involved. 

"People engage with media and celebrities in very complex and individualized ways, and some of these events and instances can 'stick' ... while others can simply fade away into obscurity," he adds. 

Whatever the execution strategy or persona attached, celebrity climate change activism efforts will almost always fall flat among one demographic: conservative voters and legislators who already have strong opinions about climate change, says Robert Duffy, a professor of political science at Colorado State University. 

In some cases, celebrity activism may lead to further polarization surrounding the issue, Dr. Duffy says in an email to the Monitor, because of "the notion that Hollywood is liberal and thus if Hollywood is for it, then I must be against it." 

While celebrity activism can play a role in shaping the public's perception of a cause, that's typically where stars' involvement in the political process ends, Duffy says. 

"Most celebrities do not have much influence over what happens later – when laws get drafted or when rules get made by agencies," he points out. At that point, policymakers rely more on people with technical or economic expertise, he says.

"That is not necessarily to dismiss the importance of their actions – getting people to pay attention to an issue or problem is a necessary first step to addressing it," Duffy adds. "But it is only the beginning of a lengthy process."