Apparently a hellish experience on a tropical beach and a run-in with a grizzly hasn't dulled Leonard DiCaprio's love for the natural world, because he's just completed work on a documentary about the dangers of climate change called Before the Flood, Hollywood Reporter reports.For the doc, DiCaprio teamed up with actor and director Fisher Stevens, a.k.a. that guy who donned brown face in Short Circuit, and aimed to show how people around the world are working to combat environmental disaster. This week, National Geographic released the first trailer for the movie, which features a slew of familiar faces, from Obama to Elon Musk to Pope Francis."Climate change is the most critical and urgent problem facing our world today, and it must be a top issue for voters this election day," DiCaprio said to the Hollywood Reporter. "Fisher and I set out to make a film that not only educates people about the challenges we face if we fail to act, but one which also shows the solutions we can implement if we can find the political will to do so."The minute DiCaprio's voiceover comes in, it's kind of tricky to watch the trailer and not imagine him just playing a character who is concerned about climate change, but it's nice to know the guy is following up on the stuff he took a stand for at the Oscars earlier this year.The documentary will air at Obama's South by South Lawn festival on October 3 and open in select theaters on October 21.Read: July 2016 Was the Hottest Month Ever Recorded, Guys