Leonardo DiCaprio Delivers Rousing Speech at U.N. Climate Summit (VIDEO)

Leonardo DiCaprio is an outspoken proponent for environmental responsibility, using his celebrity to spread awareness of the realities of climate change. The star appeared at the United Nations Climate Summit held in New York on Tuesday to deliver a rousing speech detailing the dangers of "accelerated climate change", telling the leaders in attendance that they can either "make history" or "be vilified by it."

As a newly-appointed U.N. Messenger of Peace, DiCaprio pleaded with the leaders at the U.N. General Assembly to take action before it's too late, referencing his march for Climate Change in NYC on Sunday alongside Mark Ruffalo.

"I stand before you not as an expert, but as a concerned citizen — one of the 400,000 people who marched in the streets of New York on Sunday and the billions of others around the world who want to solve our climate crisis," he said. "As an actor, I pretend for a living. I play fictitious characters, often solving fictitious problems," DiCaprio continued. "I believe that mankind has looked at climate change in that same way — as if it were a fiction, as if pretending that climate change wasn't real would somehow make it go away."

It's a stirring speech that no only has a tone of immediacy and urgency to it, but also humility. DiCaprio acknowledges that this isn't something any of us can do alone, and that we all must work together in order to offset the dangers of climate change. The future of our entire environment is at stake, and DiCaprio is making use of his celebrity to educate the public and its leaders. It's an absolutely wonderful goal, and it's propelled by a terrific speech, which you can watch in full below: