The CEO of the Leonardo DiCaprio Foundation has backed out of a debate with author Alex Epstein on the need for fossil fuels, claiming he has “urgent business” to attend to.

Epstein wrote on Facebook Thursday he learned Terry Tamminen, the Leonardo DiCaprio Foundation’s CEO, withdrew from a debate planned to take place at the Collision Conference in New Orleans in May.

Tamminen gave “no explanation to the organizers and certainly did not give me the courtesy of an apology — even though my team has been preparing for this event for weeks,” Epstein wrote on his Facebook page Wednesday.

“All I can say is that this event has been scheduled for two months,” Epstein, the president and founder of the Center for Industrial Progress and author of the book “The Moral Case for Fossil Fuels,” told The Daily Caller News Foundation.

The Collision Conference scheduled the debate between Epstein and Tamminen earlier this year. The two were to face off over the central question of whether or not humanity can abandon the use of fossil fuels.

“He is certainly outspoken and has been involved with this issue for many years,” Epstein said. “It’s unfathomable to me without explanation” that he would pull out.

“On its face, it’s another prominent person who runs their mouth of fossil fuels in the media, but won’t face someone who will challenge them,” Epstein said.

Epstein would argue the position laid out in his book that fossil fuels have allowed society to flourish in unprecedented ways, far outweighing any risks. Tamminen would argue the counterpoint that humanity needs to eschew fossil fuels to save the planet.

Epstein will now debate former Colorado Gov. Bill Ritter, a Democrat.

Tamminen is an environmental activist who served as the head of the California Environmental Protection Agency under Gov. Arnold Schwarzenegger, a Republican. Tamminen works for Leonardo DiCaprio, who’s an outspoken environmental activist.

DiCaprio started his foundation in 1998 and has since given $61.1 million in grants to dozens of environmental groups across the world.

DiCaprio has gone before the United Nations to warn about the dangers of global warming, which he blames on burning fossil fuels. The Oscar winning actor also produced a documentary series “Before The Flood” detailing the alleged dangers of global warming.

Epstein’s made a name for himself challenging the common anti-fossil fuels pushed by environmentalists, even standing in the middle of the “People’s Climate March” in 2015 holding a sign that read “I Love Fossil Fuels.”

In 2012, Epstein debated environmentalist Bill McKibben at Duke University. He’s since challenged other prominent global warming activists to debates, but with little success.

Epstein offered $100,000 to former Vice President Al Gore for a debate in 2016, and he’s challenged Bill Nye “the Science Guy” and DiCaprio himself. Epstein offered to buy first class plane tickets (or $2,000 towards a private jet for DiCaprio) for any prominent activist who wants to debate him.

But he doesn’t expect responses from them anytime soon.

“I don’t think they’re interested in debate,” Epstein told TheDCNF. “They don’t care about finding the truth.”

The Leonardo Dicaprio Foundation did not respond to TheDCNF’s request for comment.

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