A confirmation hearing Wednesday for Rep. Jim Bridenstine to be the head of NASA doubled as a referendum on climate change, to the chagrin of some Republicans.

“You can't have a hearing anymore without anyone bringing up global warming,” said Sen. Jim Inhofe, R-Okla., a climate change skeptic.

Inhofe expressed exasperation after Democrats on the Senate Commerce, Science and Transportation Committee harshly criticized Bridenstine for his climate change views.

Sen. Bill Nelson of Florida, the committee’s top Democrat, said Bridenstine, a conservative lawmaker from Oklahoma, is not qualified to lead a scientific agency because of his views on climate change and partisan record in Congress.

He is the first politician to be nominated as NASA administrator.

“Your recent public service career does not instill confidence about your leadership or ability to bring people together,” Nelson said. “Unity is so important in NASA. Your record is as divisive and extreme as any we have seen in Washington. This senator is wondering how does that fit with the leader of a technical agency where unity is often right on the line to what is going to happen with success or failure of a mission.”

NASA sends astronauts into space, but it’s also one of the top agencies for studying the climate.

Bridenstine, a 42-year-old former Navy pilot, has been dismissive of climate change.

“During the Medieval Warm Period from 800 to 1300 AD, long before cars, power plants or the Industrial Revolution, temperatures were warmer than today,” Bridenstine once said.

Nelson called Bridenstine’s views on climate change “troubling.”

Sen. Brian Schatz, D-Hawaii, later asked Bridenstine whether he believes humans are the primary contributor to climate change.

Bridenstine stopped short of saying that.

“I believe carbon dioxide is a greenhouse gas,” Bridenstine said. “I believe humans have contributed to carbon dioxide in the atmosphere.”

“To what extent?” Schatz shot back.

Bridenstine said NASA can help study the question.

“That is a question I do not have an answer to,” Bridenstine replied. “I do know humans have absolutely contributed to global warming ... Right now we are just scratching the surface to the entire system of the earth. With your help and support, we want to make sure we are getting the absolute best science. NASA is the only agency in the world that can do this kind of science, and we need to make sure we are understanding it better everyday.”

Schatz said the science is already clear.

“NASA is a scientific agency. I get that you don’t have a scientific background and I don’t begrudge you for that. Because I don’t have a scientific background. But you know what I do? I defer to scientific consensus,” he said. “And the scientific consensus is not that it’s very difficult to tell how much of climate change is attributable to human activity. The scientific consensus is climate change is primarily attributed to human activity.”

Bridenstine’s fellow Republicans defended his climate change views.

Sen. Mike Lee, R-Utah, said that NASA hasn’t acknowledged human-induced greenhouse gas emissions as the primary cause of climate change.

A statement on NASA’s website reads: “Multiple studies published in peer-reviewed scientific journals show that 97 percent or more of actively publishing climate scientists agree. Climate-warming trends over the past century are extremely likely due to human activities. In addition, most of the leading scientific organizations worldwide have issued public statements endorsing this position.”

Sen. Roger Wicker, R-Miss., meanwhile, suggested scientific consensus is an overrated concept and propagated by Democrats to advance their policy views.

“Let me say this about scientific consensus: it hasn't always been right,” Wicker said. “Here is where there is not scientific consensus. If we do everything the Left has advocated with regard to combating climate change... if we outlaw coal and make people cold in their homes and raise their power bills 300 percent, what will the effect be? Will sea level be any different at the end of 100 years? There is scientific debate about whether that will actually occur.”

Bridenstine, other Republicans, and Democrats could at least agree on one thing about climate change.

The “fear is rampant amongst our government scientists that they are going to be punished” for discussing their views on climate change, said Sen. Ed Markey, D-Mass.

Would Bridenstine pledge not to do that, Markey asked.

“Without question,” Bridenstine said. “I will not punish them.”