UNITED NATIONS: Hollywood actor Leonardo DiCaprio brought star power to the UN summit on climate change Tuesday, urging leaders to stop treating global warming as "fiction."

"As an actor, I pretend for a living. I play fictitious characters often solving fictitious problems," the actor told the summit of 120 leaders.

"I believe mankind has looked at climate change in that same way -- as if it were fiction."

Sporting a ponytail and a suit and tie, DiCaprio took to the podium at the invitation of UN Secretary General Ban Ki-moon to address a one-day summit billed as the largest gathering ever of world leaders on climate change.

The star of "The Wolf of Wall Street" and "Titanic" argued that climate change was a reality, pointing to "undeniable" extreme weather events as evidence of the impact of global warming.

The actor, who has been vocal on issues of climate change through the "Leonardo DiCaprio Foundation", called for setting a price on carbon emissions and eliminating government subsidies for oil, coal and gas.

"This is the most urgent of times and the most urgent of messages. Leaders of the world, I pretend for a living, but you do not," he said.

"Now it is your turn, the time to answer humankind's greatest challenge is now. We beg of you to face it with courage and honesty."

The man on a mission also joined Instagram to kickstart support for his cause and also took Twitter by storm.