Environmental Protection Agency chief Scott Pruitt on Thursday doubled down on climate change denial, saying he doesn’t believe carbon dioxide is to blame for 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 told CNBC. “We need to continue the debate and continue the review and the analysis.”

The majority of the scientific community agrees with the finding that humans are the primary cause of global warming. And as NASA puts it, carbon dioxide emissions are “the most important long-lived ‘forcing’ of climate change.” Scientists at the United Nations have warned that the planet will be in dire straits if nations don’t dramatically decrease their carbon emissions. So it’s problematic that the man in charge of U.S. environmental regulations doesn’t think his agency should focus on working toward that goal.

This isn’t the first time that Pruitt, who sued the EPA over a dozen times before becoming its administrator, has broken with the scientific community. He’s also said he doesn’t believe humans are the primary cause of climate change and once expressed doubt that mercury pollution is dangerous.