About a decade ago, when Leonardo DiCaprio was on the cusp of megastardom and Al Gore was the U.S. vice president, the two talked together about global warming.

Now an all-out environmental activist, DiCaprio has followed Gore’s lead by bringing a climate change documentary to the Cannes Film Festival. DiCaprio co-produced and co-wrote “The 11th Hour,” which explains how humans have changed the climate and how to fix the damage.

“It’s such an amazingly large issue, and you suddenly you feel like, what can I do? What can I do? It’s too big for me to deal with,” the 32-year-old actor told reporters Saturday in a beach cabana overlooking the Mediterranean.

DiCaprio said the environmental movement owed a great debt to Gore, whose “An Inconvenient Truth,” was shown at Cannes and won an Academy Award for best documentary feature.

“I think that movie, through the cinematic format, was able to convey science to the public and to the media in a way that it had never done before,” DiCaprio said.

He said at their meeting about 10 years ago, Gore “took his time to talk to me about the issue of global warming, which I didn’t really understand very much about, and from then on I’ve kind of been more active.”

While “An Inconvenient Truth” laid out the science behind global warming and its impact, DiCaprio’s film doesn’t try to prove that global warming exists - it accepts that it does and goes from there. It asks and responds to philosophical questions such as, how did mankind let nature deteriorate to this point?

DiCaprio also narrates the movie, which was directed by Leila Conners Petersen and Nadia Conners and includes commentary by visionaries from physicist Stephen Hawking to former Soviet President Mikhail Gorbachev.

For a new project, DiCaprio is looking for a script with an environmental theme.

“It can’t be just a film about the environment for the sake of doing it,” he said. “It’s got to be powerful and moving. … It’s got to be good.”