The star of the hit films “Titanic” and “The Wolf of Wall Street” has been vocal on the need for action on global warming through his “Leonardo DiCaprio Foundation.”
“I feel a moral obligation to speak out at this key moment in human history — it is a moment for action,” DiCaprio said in a statement.
“How we respond to the climate crisis in the coming years will likely determine the fate of humanity and our planet.”
More than 120 leaders are due to attend the summit on Tuesday that UN Secretary General Ban Ki-moon hopes will energize negotiations on reaching a deal on cutting greenhouse gas emissions.
The summit will set the stage for a crucial conference in Paris in December 2015 aimed at finalizing an agreement.
“Mr. DiCaprio is a credible voice in the environmental movement, and has a considerable platform to amplify his message,” Ban said.