Before the Flood: Watch an exclusive clip from Leonardo DiCaprio's climate change documentary 

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Making its international premiere this week at the Toronto Film Festival, the documentary

is global travelogue of a world in crisis, following Leonardo DiCaprio as he travels around the globe to chronicle the dangers of climate change. 

In September 2014, DiCaprio was named a United Nations Ambassador of Peace. He then teamed with director Fisher Stevens to highlight the areas in world most affected right now by climate disturbances and rising sea levels. Stevens is an actor in his own right (you might’ve just seen him as the pharmacist on

) though better known in recent years for his documentary work, including the Oscar-winning 2009 dolphin-slaughter exposé 

 They met with numerous climate scientists and experts, plus world leaders, including President Obama. (Longtime DiCaprio colleague Martin Scorsese serves as an executive producer; Brett Ratner is also credited as a producer.)

The film journeys to Miami, Beijing, Indonesia, and Canada, among other locales. In the exclusive clip above, DiCaprio is shown watching — and listening — to narwhals (a species of whale with long unicorn horns) along with Dr. Enric Sala while on an ice shelf near the North Pole.

“This clip is from 2015, when Leo and I spent the Fourth of July on Baffin Island in the Canadian Arctic,” Stevens tells EW. “We visited National Geographic explorer Enric Sala who was doing a study on how much sea ice has melted in the Arctic — and we were shocked to hear that by 2040 there will be no sea ice left in the summer.”

Stevens continues, “For two and a half years we went on a journey to learn about the effects of climate change. How far it has gone, why there are still people denying it, and whether it is too late to do anything about it. We’re extremely proud that National Geographic is helping us bring this odyssey to the world.” 

EW also can exclusively reveal that after its world premiere in Toronto,

will be in theaters in New York and Los Angeles starting Oct. 21, and air globally (in 171 countries and 45 languages) on the National Geographic Channel starting Oct. 30.

Check out the exclusive clip above, and the film’s poster below.

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