NASA Administrator Jim Bridenstine says he always knew humans caused climate change

NASA Administrator Jim Bridenstine introduces Vice President Mike Pence before his speech to NASA's Johnson Space Center employees discussing the future of human space exploration at Teague Auditorium Thursday Aug. 23, 2018 in Houston. less NASA Administrator Jim Bridenstine introduces Vice President Mike Pence before his speech to NASA's Johnson Space Center employees discussing the future of human space exploration at Teague Auditorium Thursday ... more Photo: Michael Ciaglo, Staff Photographer Photo: Michael Ciaglo, Staff Photographer Image 1 of / 5 Caption Close NASA Administrator Jim Bridenstine says he always knew humans caused climate change 1 / 5 Back to Gallery

NASA Administrator Jim Bridenstine appears to be changing the story of how he came to believe that humans are the cause of climate change.

During a Wednesday airing of The Weather Channel's "Weather Geeks" podcast, Bridenstine said he has always believed in climate change and that his 2013 speech denouncing federally funded climate change research was misconstrued. Climate change research was a hot button issue during his confirmation process, with many saying a climate denier shouldn't lead the space agency.

"I know that I know that carbon dioxide is a greenhouse gas and that we've put more in the atmosphere than at any other point in human history and because of that, the temperatures are warmer today than they would be otherwise and we are responsible for" that, Bridenstine said Wednesday.

"I understood it then, as a matter of fact, and I understand it now," he said.

These comments are a departure from statements he made in May during a meeting of the Senate Appropriations subcommittee on commerce, justice, science and related agencies, where he was asked about climate change by U.S. Sen. Brian Schatz, D-Hawaii.

"The National Climate Assessment, that includes NASA, and it includes the Department of Energy, and it includes NOAA, has clearly stated it is extremely likely, [that] is the language they use, that human activity is the dominant cause of global warming, and I have no reason to doubt the science that comes from that," Bridenstine said, according to the Washington Post.

"Is it fair to call this an evolution of your views?" Schatz responded.

"Yes," Bridenstine said.

SWORN IN: Former Oklahoma congressman takes helm of NASA

Bridenstine first was nominated by President Donald Trump in fall 2017 to lead the space agency. But his confirmation process was fraught with delays and concerns over his ability to lead the agency, in large part because of his beliefs on climate change. Bridenstine was finally confirmed in April.

His detractors cite his 2013 speech in calling him a climate change denier, Bridenstine said Wednesday, but he "totally forgot I gave that speech until I was nominated."

The 2013 speech was a means of advocating for additional federal dollars for weather prediction modeling, after a massive tornado plowed through his home state of Oklahoma and claimed the lives of almost two dozen people, Bridenstine explained.

Global temperatures hadn't risen in a decade, he said in 2013, and "even climate change alarmists admit that the number of hurricanes hitting the U.S. and the number of tornado touchdowns have been on a slow decline for over a hundred years."

The "Weather Geeks" podcast, which airs every Wednesday, can be downloaded on iTunes, Stitcher, Overcast, and We Love Weather.

Alex Stuckey covers NASA and the environment for the Houston Chronicle. You can reach her at alex.stuckey@chron.com or Twitter.com/alexdstuckey.