In a 24-hour period on December 2, Racing Extinction may just become the most-watched documentary in history. The film from director Louie Psihoyos and producer Fisher Stevens, who made the Oscar-winner The Cove, debuts Wednesday on the The Discovery Channel and with its partners worldwide. John Hoffman, Discovery’s executive vice president for documentaries and specials, estimates a potential audience of 2.4 billion—and at least 500 million expected to watch.

“I’m trying to blow this up and get it to the widest possible audience, ever,” says Psihoyos, which looks at global warming as a potential extinction-level event, and particularly at its impact on ocean life. Just as The Cove took the form of a heist movie, Racing Extinction has its own share of spycraft, with women bringing hidden cameras into sushi restaurants that are serving contraband meat and activists infiltrating a Hong Kong factory that sells illegal shark fins. Appropriately for a movie about the ocean, Racing Extinction also goes beneath the waves, as you can see in this moving clip about a diver’s rescue of a Manta ray in trouble.

“Discovery can get more eyes on your movie than anybody else I can think of,” says Stevens, describing how the reaction at Sundance to Racing Extinction was so much bigger than for The Cove. “Even though The Cove won all these awards and was a really great movie, not many people saw it. Louie and I both decided before Sundance if we could find anyone to buy it, we wanted to find someone who could bring it to the biggest audience.”

The historic launch on December 2 is poised to do just that—and with the climate talks in Paris ongoing, amplify a conversation that is only becoming more important. Says Hoffman, “This is a movie that defines an issue that the entire world must pay attention to.”