By Alexandra Rosenmann

American astrophysicist, celebrated author and director of the Hayden Planetarium at New York's Natural History Museum, Neil deGrasse Tyson, joined Stephen Colbert on Tuesday night. DeGrasse Tyson weighed in on claims made by Trump's new U.S. Environmental Protection Agency head.

Scott Pruitt "said he does not believe CO2 is the control knob for climate change," Colbert reminded his guest. "What is the present consensus of CO2 and climate change?"

"It's a greenhouse gas," deGrasse Tyson answered.

"People just talk," he continued. "I can't chase what people say because it flutters with the breeze."

DeGrasse Tyson warned that if Pruitt "puts down some legislation that requires that everyone [must go along with his beliefs], oh! Oh, my God! Hold me back!" he exclaimed.

"I'll hold you back," Colbert offered. "He's going to blow," he told the audience. "He's a crystal geyser!"

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Reposted with permission from our media associate AlterNet.