Story highlights "We need to continue the debate and continue the review and the analysis," he said

Sen. Brian Schatz called Pruitt a "climate change denier"

(CNN) The head of the Environmental Protection Agency administrator said Thursday he does not believe that carbon dioxide is a primary contributor to global warming -- a stance at odds with leading climate scientists.

Scott Pruitt made the comment to CNBC's Joe Kernen when he was asked if he believes that carbon dioxide "is the primary control knob for climate."

"I think that measuring with precision human activity on the climate is something very challenging to do and there's tremendous disagreement about the degree of impact, so no, I would not agree that it's a primary contributor to the global warming that we see," he said on CNBC's "Squawk Box."

"But we don't know that yet," he added. "We need to continue the debate and continue the review and the analysis."

Pruitt, who frequently sued the EPA while attorney general of Oklahoma, was repeatedly questioned during his confirmation hearings because of his positions on climate change and other environmental issues. At a hearing, Pruitt told senators, "Science tells us the climate is changing and human activity in some matter impacts that change."

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