President Obama and actor Leonardo DiCaprio make their way off stage after taking part in a discussion on climate change during the South by South Lawn (SXSL) festival at the White House on Oct. 3. (Mandel Ngan/AFP/Getty Images)

Actor Leonardo DiCaprio kicked off his onstage discussion at the White House with President Obama on Monday night before the screening of his new documentary “Before the Flood” with a nod to the presidential campaign.

During the White House’s “South by South Lawn” session, DiCaprio declared the issue of climate change a matter of settled science and knocked GOP candidate Donald Trump — who has suggested that the phenomenon is a “hoax” — without naming him. “If you don’t believe in climate change, you don’t believe in facts, and science, and empirical truths,” DiCaprio said, to applause from the audience. (To be fair, this was a crowd that went nuts at the mere mention of a carbon tax). “And, in my humble opinion, [you] should not be allowed to hold public office.”

Obama, for his part, was mostly serious during the hour-long talk about environmental issues. But he drew laughs when discussing ways to draw in people from all over the political spectrum. Sportsmen and hunters, the president said, might not agree with traditional environmentalists on gun rights. But they could find common ground wanting to preserve the environment because of their love for the outdoors, he suggested. “I mean, they might not want to get mauled by a grizzly bear,” he said, referring to a famously graphic scene in a recent DiCaprio film, “The Revenant.” “That looked, ah, a little severe.”