When Leonardo DiCaprio accepted his highly anticipated Oscar this year, he didn’t deliver a typical acceptance spiel, thanking everyone who made his win possible. Instead, he used this 45-second platform to send an important message to all 34.3 million viewers: global warming is real. “Making The Revenant was about man’s relationship to the natural world. A world that we collectively felt in 2015 as the hottest year in recorded history,” he said. “Climate change is real, it is happening right now. It is the most urgent threat facing our entire species, and we need to work collectively together and stop procrastinating.”

As temperatures and sea levels consistently creep up worldwide, celebrities have increasingly become environmental advocates, endorsing particular causes that they encourage their fans to support. While at first glance, these celebrities may seem heroic, using their power for good, the influence of celebrities in the environmental arena is a source of contention.

Peter Levine, a Philosophy Research Professor and the Director of Tisch College’s Center for Information and Research on Civic Learning and Engagement (CIRCLE), noted the problems with trusting celebrity endorsements. Celebrities have “disproportionate influence, for reasons that seem irrelevant,” he explained. “They don’t get their influence from their environmental expertise.”

Dillon Bowen, the Co-Founder and President of Tufts Effective Altruism, echoed these sentiments. “Every donation comes with an opportunity cost. If a celebrity endorsement ‘raises’ money by convincing people to give to one charity, it’s likely those donors will give that much less to other charities,” he said. “So money isn’t being raised; it’s being moved. Celebrities also have no more idea than anyone which charities are most effective…Instead of relying on celebrities, we should be relying on experts—people who have dedicated years of their lives to researching effective charities.”

Many prominent celebrities also create their own charities rather than support pre-existing ones. Big names like Brad Pitt, Jack Johnson, and even DiCaprio himself, have established their own organizations targeting particular environmental causes. “There is a general temptation to try to start something new instead of supporting what exists, and that can be problematic,” Levine noted. “Too often, people with the money, fame, power, or talent choose to start something of their own instead of supporting existing organizations that need their help.” When celebrity charities raise money, that money is again being diverted from other charities, which may be more effective in achieving their missions than new, celebrity-sponsored endeavors are.

Moreover, charities that do receive celebrity endorsements must risk the volatility of that celebrity’s image. In the Guardian, Peter Stanford—a journalist, director of the Longford Trust, and 20-year board chair of Aspire, a British charity—asked readers to consider the possibility of a scandal. “Might the celebrity to whom you have hitched your wagon, as it were, appear the following week in a front-page exposé in the tabloids? What damage will that do to your charity’s name?”

Laura Forte, a President of Sea Turtle Conservancy Board of Directors, compared the situation to problems faced by organizations affiliated with Tiger Woods when he was embroiled in scandal regarding his infidelity and sex addiction. She noted that “nonprofits need to have an even cleaner reputation” than other organizations; their reliance on public support depends on the appearance of full dedication to the goal at hand, not getting distracted by drama. Though connections to a celebrity can harm a charity during a scandal, when not involved in a scandal, celebrities may not even be bringing significant positive attention to these causes.

Stanford cautioned that celebrity advocacy can detract from the charity’s mission. “Celebrities can get in the way, the messenger becoming more important than the message,” he wrote.

Furthermore, research on the use of celebrities in advertising campaigns suggests that its influence is minimal. A study from Harris Interactive found that while using humor in advertisements resonated with 47 percent of respondents, celebrity endorsements influenced only 12 percent. However, as this poll was self-reported, it doesn’t account for the subconscious effects a celebrity advertisement may have on viewers—because of this flaw, the success of a celebrity endorsement is a hard quantity to measure.

Do these statistics hold true for environmental organizations in particular? A 2008 research study led by A. Trevor Thrall—an associate professor at George Mason University and Senior Fellow at the Cato Institute—found that celebrities did not bring any more news coverage to the environmental causes they were supporting. Although environmental groups associated with more celebrities were slightly more likely to appear in a newspaper story with a celebrity, celebrities with higher “star power” did not bring more news coverage to the groups they supported.

Though mainstream news media does not seem to be strongly influenced by celebrities, this does not mean that celebrity advocacy does not draw the attention of the public to the issues for which they advocate. Fans of the celebrity may still be attracted to causes they support, which entices charities to seek celebrity endorsements, whether or not they gain media coverage from them. Speaking for the Sea Turtle Conservancy, Forte said, “I think a celebrity endorsement would help in the public eye and increase donations.”

Convincing a celebrity to support an environmental charity can be a challenging undertaking. Forte shared the advice she had received for appealing to celebrities to endorse the Sea Turtle Conservancy: “Charities generally pitch to PR companies. Agents won’t generally get back to you…I suggest you hit up publicists…Especially go after the animal lover/vegan/PETA-loving celebrities…I think they would get on board the quickest!” However, even by following these suggestions, a celebrity endorsement is not guaranteed. “It’s much easier if someone knows a celebrity,” Forte said. Without connections, it can be incredibly difficult for a charity to convince a big name to associate with them.

The difficulty of reaching and winning over celebrities for a charity raises the question of whether it is worthwhile for charities to focus their efforts on garnering the support of stars. Stanford lamented the many cases he has witnessed of charity chief executives and chairs hoping to rely on celebrity appearances and endorsements. Instead, Stanford wrote, charities should be focusing on “fine-tuning the mechanics of the events, or honing their campaigning message so it genuinely touches a nerve with the public.”

However, if organizations can strike a balance between celebrity endorsements, a clear mission, and effective leadership, perhaps the celebrities can positively affect the environmental causes they endorse. Justin Forsyth, the CEO of Save the Children, argued in the Guardian that celebrities can bring much-needed attention to important issues, and charities should use that to their advantage. “Of course the celebrity touch isn’t everything…” he wrote. “But the support of an impassioned celebrity for that cause can help reach new audiences with that message,”

Tina Woolston and Betsy Byrum, from the Tufts Office of Sustainability, argue that our environment’s future depends on the collaboration of many types of organizations. “We are currently facing a myriad of urgent environmental issues…And these really complex and urgent problems require the cooperation and involvement of a whole host of actors from the public, private, and nonprofit sectors in order to be addressed in any sort of effective and comprehensive manner,” Byrum said.

Byrum and Woolston pointed to the Paris climate talks that were held in December as an example of successful collaboration, which brought about a legally binding, worldwide climate agreement—the first legislation of its kind, which appears to be a promising step in the right direction. “Are environmental nonprofits/charities a panacea for addressing issues like climate change? No. But can they play an important role? I think so,” said Byrum.

Levine also noted that celebrities might be able to meaningfully draw attention to the important world of nonprofits. “It could be that by endorsing a range of charities, celebrities do good in the aggregate—they raise awareness of the whole nonprofit sector…it’s not just about each endorsement but about the overall ideology or political philosophy that is conveyed by having celebrities endorse charities,” he said.

While the merits of celebrity involvement remain up for debate, the continuing decay of the world around us necessitates immediate and drastic action by as many people as possible—and if stars like Leo choose to champion the cause, maybe it’s best to let them.