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Scott Pruitt, Donald Trump's choice to head the Environmental Protection Agency, questioned the human impact on climate change and called his personal opinion on the issue “immaterial” during his confirmation hearing Wednesday.

“I believe the ability to measure with precision the degree of human activities impact on the climate is subject to more debate on whether the climate is changing or whether human activity is contributing to it,” the Oklahoma attorney general said.

When pressed by Democratic Sen. Bernie Sanders on why he thinks the climate is changing, Pruitt responded: “My personal opinion in immaterial.”

Democrats peppered Pruitt with tough questions about his views on global warming, ties to the oil and gas industry and legal actions taken against the EPA at the hearing. As attorney general, Pruitt aggressively fought against regulations imposed by the agency he was nominated to run and was one of 28 attorneys general to sue the federal government over regulations put in place by the Obama administration to limit carbon emissions.

"For too long, the Environmental Protection Agency has spent taxpayer dollars on an out-of-control anti-energy agenda that has destroyed millions of jobs, while also undermining our incredible farmers and many other businesses and industries at every turn," President-elect Donald Trump said in a statement announcing the pick, adding that Pruitt would "reverse this trend."

The concept of global warming was created by and for the Chinese in order to make U.S. manufacturing non-competitive. — Donald J. Trump (@realDonaldTrump) November 6, 2012

"I do not believe that climate change is a hoax"

Pruitt said point-blank that he disagrees with the president-elect’s belief that climate change is a hoax.

"I do not believe that climate change is a hoax," Pruitt said.

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“That’s important for the president to hear,” Massachusetts Sen. Ed Markey said.

But it was later when Sanders pressed Pruitt on why he thought the climate was changing when the nominee questioned human's impact and called his own thoughts on the subject “immaterial.” The job of the EPA administrator, Pruitt said, is to enforce the laws passed by Congress.

“While you are not certain, the vast majority of scientists are telling us that if we do not get our act together and transform our energy system away from fossil fuel, there is a real question as to the quality of the planet,” Sanders said.

During the hearing, government scientists announced 2016 was the third-straight hottest year on record.

Under fire for ties to oil

Democratic Sen. Sheldon Whitehouse pressed Pruitt on his fundraising from oil companies. “A great deal of your fundraising comes from these organizations who are in the energy sector and devoted to fighting climate change,” Whitehouse said. Pruitt said he attended fundraisers for a number of companies with ties to the oil and gas industry but did not recall directly asking them for political contributions.

Oil company’s influence on EPA letter

Democratic Sen. Jeff Merkley said a letter to the EPA sent from Pruitt's letterhead was copied nearly identically from an oil company and shows he lobbied for the industry as attorney general. “You used your office as a direct extension of an oil company rather than a direct extension of the interests of the public health of the people of Oklahoma,” Merkley said.

The New York Times found Pruitt added his signature to a three-page letter written by Devon Energy lawyers with few words changed. Devon is one of Oklahoma’s largest oil companies.

The letter accused the EPA of overestimating the amount of methane released from drilling natural gas wells.

“That was an effort that was protecting the state’s interest in making sure that we made the voices of all opponents heard on a very important industry in our state,” Pruitt said.

“The state of Oklahoma has an oil and gas industry that is vibrant to our state as you might imagine, just like may of you have industry in your state. There was a concern expressed by that industry, by many folks in that industry, about the over estimating that occurred with that methane rule,” he added.

Potential conflicts with ongoing EPA litigation

Democratic Sen. Ed Markey warned that Americans will view the EPA as “every polluters ally” unless he commits to completely recusing himself from ongoing litigation Oklahoma has taken against the EPA.

Markey said there are eight ongoing cases he has brought against the EPA as attorney general.

“Will you agree to recuse yourself from those lawsuits which you brought as the attorney general of Oklahoma, not just for one year, but the entirety of the time you are the administrator of the EPA?” Markey asked.

“I have every willingness and desire to recuse as directed by the EPA ethics council. And if directed to do so, I will do so,” Pruitt said before being grilled on why he would not commit to recusing himself at the hearing.

“Otherwise, honestly, people are going to think it’s not just the fox guarding the hen house. It’s the fox destroying the hen house,” Markey said.