Did Leonardo DiCaprio mistake a chinook for climate change?

By Gayathri Vaidyanathan | 03/01/2016 08:08 AM EST

Was Leonardo DiCaprio wrong?

Was Leonardo DiCaprio wrong?

Albertans in Canada and some scientists think so. They took to Twitter yesterday to mock DiCaprio’s suggestion during his Academy Award acceptance speech Sunday that his experience filming "The Revenant" could be linked to climate change.

DiCaprio, who starred in the survival epic about a frontiersman attacked by a bear in the snowy wilderness of the Great Plains, used his high-profile Oscar moment to draw attention to global warming. In doing so, he noted that his film crew was forced to relocate to Argentina from Calgary in southern Alberta for the movie’s final scenes. The reason: absence of snow.


"Our production needed to move to the southern tip of this planet just to be able to find snow," DiCaprio said Sunday night. "Climate change is real, it is happening right now."

Some weren’t buying the link.

"If you are going to advocate for climate action at this level of visibility, you ARE NOT allowed to be this sloppy about the science. Sorry," Chris Turner, an award-winning sustainability writer and Calgary resident, wrote on Twitter.

But other scientists came to DiCaprio’s defense, pointing out that there has been a perceptible decrease in snow cover globally since 1980, and the northern latitudes are, indeed, warming.

So, who is right? It depends entirely on the frame of reference.

Embrace the snow eater

In the winter of 2014-15, DiCaprio, "The Revenant" director Alejandro G. Iñárritu and their crew filmed near Calgary, where wintertime temperatures plunge on average to 5 degrees Fahrenheit. Bad days clock in at minus 40 F. Shooting in these conditions was grueling, DiCaprio told Yahoo.

"Whether it’s going in and out of frozen rivers, or sleeping in animal carcasses, or what I ate on set. [I was] enduring freezing cold and possible hypothermia constantly," he said.

Revenant poster
Leonardo DiCaprio said filming of “The Revenant” was affected by climate change. Some scientists disagree but praised the attention he brought to the issue at the Academy Awards. | Photo courtesy of Wikipedia.

DiCaprio said he was caught off guard when strong, dry winds suddenly blew through southern Alberta in the middle of those conditions.

These winds are called chinook, an aboriginal word meaning "snow eater." They blow down the eastern slopes of the Rocky Mountains and bring much-desired temporary warmth and snowmelt to the southern part of the province. They are beloved by Calgarians, according to a 1997 study by Lawrence Nkemdirim, an emeritus professor of geography at the University of Calgary. Chinooks increase the sense of well-being during drab, cold winters, Nkemdirim wrote.

On Jan. 25, 2015, a chinook boosted temperatures to 63 F and people basked on outdoor patios in shorts drinking Slurpees, the Canadian Broadcasting Corp. reported.

DiCaprio said he was stunned by the sudden shifts in weather that January.

"We would come and there would be 8 feet of snow, and then all of a sudden a warm gust of wind would come," he said during a screening in Beverly Hills on Nov. 22, 2015, according to Variety. The crew was shooting entirely outdoors in natural light and found the weather unpredictable.

The crew had to look elsewhere for similar stark, snow-covered landscape and settled on Argentina.

Calgarians revolt

DiCaprio has a long history of activism on climate change, and the Leonardo DiCaprio Foundation donated $15 million to environmental causes and climate change research in 2015.

"And, of course, I’m not talking about climate change in relation to movies and how difficult it’s going to be to make movies," DiCaprio said at the November screening. "but it was scary. I’ve never experienced something so firsthand that was so dramatic. You see the fragility of nature and how easily things can be completely transformed with just a few degrees difference. It’s terrifying, and it’s what people are talking about all over the world. And it’s simply just going to get worse."

Calgarians, who can be broadly labeled green, socialist-leaning liberals, exploded. The Calgary Sun and CBC reported that DiCaprio’s comments were "roundly mocked." Calgarians left scathing comments on the Variety interview.

The sparse snow cover had nothing to do with climate change, they complained. It was caused by the chinook.

Chinooks typically originate as hurricanes in the Bering Sea. Polar winds from the storms move inland and hit the Coast Mountains in British Columbia and climb. Along the way, the water vapor condenses to rainfall and releases heat to the atmosphere. The air mass then climbs over the Rocky Mountains and descends onto the Albertan prairie. By then, the winds are dry and warm — ideal for evaporating snow.

"Chinooks are just part of our [southern Alberta’s] winters," Chris Hugenholtz, an earth scientist at the University of Calgary, said in an email.

Nkemdirim’s 1997 study is the most comprehensive published on chinook trends. It finds that chinook frequency did not change between 1951 and 1990. No one has updated the results for 1990 onward.

The study concluded that chinooks will "not be a factor" in a warming climate.

Defenders: DiCaprio had a broader point

Hugenholtz did not think DiCaprio’s Oscar night comments were problematic.

"I know he might’ve misstepped on the link between snow/temperature and climate change in comments made previously, where he mistook the effect of a common chinook, but I didn’t hear this exact connection in his speech at the Oscars," Hugenholtz said. "In my view, that’s just a statement about the challenge in finding snow cover to complete the filming."

Michael Mann, a climatologist at Pennsylvania State University, defended DiCaprio on Twitter yesterday morning. No one could attribute any particular weather events, such as a chinook, to climate change, he said. But that was not DiCaprio’s point during the Oscars. The actor dropped the chinook reference, and it was a simple statement on the difficulty of finding snow.

It is undeniable that winters all over western Canada were unusually warm in 2014 and 2015, and snow cover was harder to find, Mann said.

"The larger context here means that the crew was far more likely to encounter the conditions that Leo’s crew encountered [low mountain snow cover] in western Canada than they otherwise would have been," Mann said.

"It is a shame that some folks appear to be blurring this very simple point, sometimes it appears — I’m afraid — as part of an ad hominem attack on DiCaprio and his efforts to raise awareness about the threat of climate change."

Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research, did not watch the Oscars, but he deconstructed the observed snowfall trends in North America.

For every 1 F increase in temperature, the atmosphere can hold an extra 4 percent of moisture, Trenberth said. So, there would be bigger dumps of snow in midwinter when the temperatures hold below freezing, he said. But winters would get shorter, and it would be harder to find snow cover at the end of winters, he said.

"In midcontinental regions in midwinter, we are more likely to get more snow, but the snow season is shorter at both ends," he said.

This translates to a slight increase in snow cover from December to February and huge losses in the spring, he said.