Leonardo DiCaprio is king of the warming world.

After he called climate change “the most urgent threat facing our entire species” while accepting his first Oscar earlier this year, climate-related coverage in traditional media didn’t really react. But social media did.

Tweets and Google searches on the subject hit record highs, according to a new study published in the journal PLOS ONE.  

The “DiCaprio effect” on Twitter was more than five times as potent as Earth Day and more than three times as impactful as a gathering of policymakers in Paris that ended with a global climate accord late last year.

DiCaprio was in Paris too. And he talked about climate change in New York before the deal was reached, and as it was signed.

But the Oscars came with an audience of 34.5 million live viewers.

“The Revenant was about man's relationship to the natural world—the world that we collectively felt in 2015 as the hottest year in recorded history,” DiCaprio said after winning a best actor award. “Our production had to move to the southernmost tip of this planet just to be able to find snow.” 

People were paying attention. The study showed Google searches for “hottest year” spiked significantly the next day, while searches for terms not mentioned in his speech stayed more or less the same.


Leo DiCaprio graph


(image courtesy of PLOS ONE)

“Imagine if Leo had talked about a carbon tax,” said John Ayers, a San Diego State University professor who led the study along with Eric Leas at the University of California, San Diego.

DiCaprio isn’t the only celebrity to have this kind of social impact. There was the Angelina Jolie effect on breast cancer. And the Charlie Sheen effect on HIV prevention.

“Our Charlie Sheen paper caused public health to engage on the issue,” Ayers said.

Uncovering both the “Sheen effect” and the “DiCaprio effect” relied in part on the Bloomberg Terminal’s news archives and a member of Bloomberg’s data science team, Mark Dredze.