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People really do pay attention to climate change — when Leonardo DiCaprio talks about it

Actor Leonardo DiCaprio accepts the award for Best Actor in “The Revenant” at the Oscars on Feb. 28. (Mark Ralston/AFP)

Do celebrities matter? The answer — modern, big data approaches are showing — is pretty clearly “yes.”

Earlier this year, a team of researchers documented that when Charlie Sheen told the world that he had HIV, media attention to the virus — which had been in long decline — spiked massively.

And now, many of the same researchers are back with another demonstration. They find that when Leonardo DiCaprio used his Oscar speech earlier this year to exhort action on climate change, tweets and Google searches about the topic were enormous and, at least in the case of tweets, appear to have set a new record based on analyses between 2011 and the present.

“A single speech, at a very opportunistic time, at the Oscar ceremony, resulted in the largest increase in public engagement with climate change ever,” says John Ayers of San Diego State University, who completed the work with colleagues from the University of California San Diego, the Santa Fe Institute, and other institutions. Their study was just published in the open access journal PLOS One.

DiCaprio, winning the Oscar for best actor for “The Revenant” on Feb. 28, said this:

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. Our production needed to move to the southern tip of this planet just to be able to find snow. 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. We need to support leaders around the world who do not speak for the big polluters or the big corporations, but who speak for all of humanity, for the indigenous peoples of the world, for the billions and billions of underprivileged people who will be most affected by this, for our children’s children, and for those people out there whose voices have been drowned out by the politics of greed.

When DiCaprio said this, 34.5 million people were watching.

Ayers and his colleagues used a combination of media coverage searches using the Bloomberg Terminal, Twitter content searches and Google trends search data to examine the consequences. They also closely examined how the public response to this moment compared with past attention to climate change at key times, including during the Paris climate negotiations and the 2015 Earth Day.

They also used a modeling approach to estimate what typical media coverage and social media engagement with the subject of climate change would have been if DiCaprio had not spoken out — what a more “normal” level of attention would be.

The result was that while there was virtually no news media response to DiCaprio (most journalists don’t take their marching orders from celebrities speaking out), the social media and search response was enormous.

“Tweets mentioning climate change or global warming were 636 percent higher than expected the day DiCaprio spoke,” the study finds.

Here’s a figure from the study showing as much, through a comparison of media coverage and tweets about climate change over time:

The authors add that when DiCaprio spoke, the total number of Tweets that contained the phrases “climate change” or “global warming” “were at the highest recorded value in our database with more than 250,000 tweets on that day.”

And then there were the Google searches. These, too, spiked, so much so that it represented the “third-highest point ever recorded for climate change or global warming on Google trends.”

Here, again, is a chart provided by the authors, showing that the searches often used DiCaprio’s actual words:

The significance of this, says study author Ayers, is that celebrities speaking out really matters, even if it doesn’t make the traditional news.

“Even though it didn’t get that coverage, speaking up on it can still make a difference, by driving record levels of engagement,” he says.

Ayers adds that with the methods used in the study, it could be possible at some time in the future to actually time further advocacy and engagement campaigns to maximize the impact of a moment such as the DiCaprio speech.

“Imagine if you will that hundreds of leaders came out the next day and piggybacked on this message,” he says. “That’s hypothetical, but with these data, that’s hypothetically possible in the future. We rely entirely on free, publicly available, and real time data.”

More generally, the lesson is that when it comes to waking people up about changes to the planet, it can’t just be climate scientists talking all the time.

“The scientific community must adapt to the 21st century dynamic communication landscape and ready itself for the next opportunity to harness the agents of change,” the study concludes.