NASA Administrator Jim Bridenstine James (Jim) Frederick BridenstineNASA publishes Artemis plan to land first woman, next man on moon NASA is in the market for moon rocks Overnight Defense: Trump hosts Israel, UAE, Bahrain for historic signing l Air Force reveals it secretly built and flew new fighter jet l Coronavirus creates delay in Pentagon research for alternative to 'forever chemicals' MORE says he changed his mind on the existence of man-made climate change because he “read a lot.”

“I heard a lot of experts, and I read a lot,” Bridenstine told The Washington Post on Tuesday. “I came to the conclusion myself that carbon dioxide is a greenhouse gas that we've put a lot of it into the atmosphere and therefore we have contributed to the global warming that we've seen. And we've done it in really significant ways.”

The former congressman from Oklahoma had long denied the scientific consensus on climate change and said in a 2013 speech on the House floor that "global temperatures stopped rising 10 years ago."

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In May, Bridenstine first announced publicly that he now believes human activity is the main cause of climate change.

“The National Climate Assessment that includes NASA, and it includes the Department of Energy and it includes NOAA, has clearly stated it is extremely likely — is the language they use — that human activity is the dominant cause of global warming,” he said at a Senate Appropriations Committee subpanel's hearing last month.

President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE and Environmental Protection Agency Administrator Scott Pruitt Edward (Scott) Scott PruittJuan Williams: Swamp creature at the White House Science protections must be enforceable Conspicuous by their absence from the Republican Convention MORE have not made similar pronouncements, however.

Trump has long denied climate change is real, once saying without evidence that it was “created by and for the Chinese in order to make U.S. manufacturing noncompetitive.”

Last December, the president tweeted during a period of cold weather that “perhaps we could use a little bit of that good old Global Warming."

In March, Pruitt told CNBC that he didn't think humans were a primary contributor to climate change, saying there's "tremendous disagreement about the degree of impact."