Actor and environmental activist Leonardo DiCaprio went after President Donald Trump and other world leaders for their positions on climate change, accusing them of “denying the very science of this climate catastrophe.”

Addressing the Global Citizen Festival in New York on Saturday, the Once Upon a Time in Hollywood star focused on the Trump administration’s decision to withdraw from the Paris climate accord two years ago.

“It’s become clear that our political leaders have failed to live up to promises that we celebrated that day,” DiCaprio said. “Our future is being gambled away, and our leaders, those whom we entrust to protect us and set the example, are either failing to stop these dangerous trends or, in some cases, denying the very science of this climate catastrophe.”

“Unless you live in an alternate reality, there’s no more time for denial,” he continued. “A carbon-neutral future is the only way we will inherit a planet capable of sustaining life on Earth as we know it.”

However, the Oscar-winning actor appeared to place his faith in the younger generations and took aim at Donald Trump for his tweets about 16-year-old Swedish activist Greta Thunberg.

“While our leaders continue to deny the science, I can tell you one thing for certain. The youth is not,” he declared. “Last people young people led the world in a strike. Millions of brave individuals did more than simply walk out of their schools and places of employment… These people have said clearly, definitively and without fear, the time for inaction is now over.”

She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see! https://t.co/1tQG6QcVKO — Donald J. Trump (@realDonaldTrump) September 24, 2019

“Yet surprisingly, some reacted to this movement with insulting tweets and negative talking points,” he said in reference to Trump’s comments. “Individuals that seem to care more about profit and their own self-interest than about your future.”

Di Caprio remains Hollywood’s most prominent environmental activist, having set up his own environmental organization, Earth Alliance, which recently announced a $5 million fund to protect parts of the Amazon rainforest affected by forest fires.

The 44-year-old star has also faced accusations of hypocrisy, particularly with regard to his use of a gas-guzzling private jet, which he has admitted means his “carbon footprint is bigger than most peoples.”

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