Environmental Protection Agency head Scott Pruitt on Thursday said he doesn’t believe carbon dioxide is a main contributor to global warming.

“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.”

Pruitt, who sued the EPA 14 times when he was Oklahoma attorney general, said the record is still unsettled.

“But we don’t know that yet. … We need to continue the debate and continue the review and the analysis.”

The agency he now heads determined in 2009 that carbon dioxide and five other greenhouse gasses are a threat to public health.

Asked if he would roll back that finding, he suggested Congress should take another look at it.

“I think all those things need to be addressed as we go forward but not least of which is the response by the legislative branch with respect to the issue,” he said.

Pruitt, who has close ties to Oklahoma’s oil and gas industries, was confirmed last month 52-46 in the Senate.

Senators and environmental advocacy groups opposing his confirmation called Pruitt a “climate change denier” who would remove clean water and air protections.