Donald Trump’s campaign manager said Tuesday that her candidate does not believe in man-made climate change following a heated—and ambiguous—exchange on the issue at the first presidential debate.

“He believes that global warming is naturally occurring,” Kellyanne Conway said on CNN. “There are shifts naturally occurring.”

Conway’s remark clarifies a remark from Trump during Monday’s debate. Hillary Clinton accused Trump of saying climate change was a “hoax perpetrated by the Chinese.” Trump responded saying, “I do not say that,” but he did not clarify exactly what part of Clinton’s comment he found objectionable.

Trump has repeatedly questioned the science of climate change and as recently as 2012 called it a myth created by China. Throughout the campaign he has promised to gut U.S. efforts to address the issue.

Nearly all climate scientists agree that humans are contributing to climate change and urgent measures are needed to address it. Both candidates offered their views on how to address climate change—and other key science issues under presidential purview—in a survey of science policy earlier this month. In those answers, Trump dismissed global warming saying “there is still much that needs to be investigated” while Clinton outlined her plan.

A group of 375 leading scientists, including 30 Nobel laureates, penned a letter criticizing Trump’s stance on climate change earlier this month.

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Write to Justin Worland at justin.worland@time.com.