UNITED NATIONS: Hollywood actor and environmental campaigner Leonardo DiCaprio urged world leaders signing the Paris climate deal on Friday to deliver on their commitments to cut greenhouse gases, telling them: “The world is now watching.”

“You will either be lauded by future generations or vilified by them,” said DiCaprio at the UN ceremony where 171 nations lined up to sign the landmark accord.

“We can congratulate each other today, but it will mean absolutely nothing if you return to your countries and fail to push beyond the promises of this historic agreement.”

“Now is the time for bold, unprecedented action.”

The actor, who this year won his first Oscar for his portrayal of a frontiersman in “The Revenant,” spoke in his role as UN Secretary-General Ban Ki-moon’s “messenger of peace with a special focus on climate change.”

The 41-year-old celebrity returned to the United Nations after delivering a much-watched address to world leaders during a UN climate summit in September that set the tone for the Paris accord.