US president Donald Trump has accused climate change scientists of having “a very big political agenda.”
However, he has talked down his claim that climate change is a hoax but said he does not know if it is manmade.
In an interview with CBS' 60 Minutes, Mr Trump said he does not want to put the US at a disadvantage in responding to climate change.
"I think something's happening. Something's changing and it'll change back again," he said.
"I don't think it's a hoax. I think there's probably a difference. But I don't know that it's manmade. I will say this: I don't want to give trillions and trillions of dollars. I don't want to lose millions and millions of jobs."
Mr Trump called climate change a hoax in November 2012 when he sent a tweet stating, "The concept of global warming was created by and for the Chinese in order to make US manufacturing non-competitive."
He later said he was joking about the Chinese connection, but in years since has continued to call global warming a hoax.
"I'm not denying climate change," he said in the interview. "But it could very well go back. You know, we're talking about over a ... millions of years."
Temperature records kept by Nasa and the National Oceanic and Atmospheric Administration show that the world has not had a cooler-than-average year since 1976 or a cooler-than-normal month since the end of 1985.
Mr Trump, who is scheduled on Monday to visit areas of Georgia and Florida damaged by Hurricane Michael, also expressed doubt over scientists' findings linking the changing climate to more powerful hurricanes.
"They say that we had hurricanes that were far worse than what we just had with Michael," said Mr Trump, who identified "they" as "people" after being pressed by 60 Minutes correspondent Leslie Stahl.
She asked, "What about the scientists who say it's worse than ever?"
The president replied, "You'd have to show me the scientists because they have a very big political agenda."
Mr Trump's comments came just days after a Nobel Prize-winning Intergovernmental Panel on Climate Change issued a warning that global warming would increase climate-related risks to health, livelihoods, food security, water supply, human security and economic growth.
The report detailed how Earth's weather, health and ecosystems would be in better shape if the world's leaders could somehow limit future human-caused warming.