Lee Zeldin, the administrator of the Environmental Protection Agency, said on Tuesday the Trump administration would revoke the scientific determination that underpins the government’s legal authority to combat climate change.
Speaking on a conservative podcast called “Ruthless,” Mr. Zeldin said the E.P.A. planned to rescind the 2009 declaration, known as the “endangerment finding,” which concluded that planet-warming greenhouse gases pose a threat to public health. The Obama and Biden administrations used that determination to set strict limits on greenhouse gas emissions from cars, power plants and other industrial sources of pollution.
“Repealing it will be the largest deregulatory action in the history of America,” Mr. Zeldin said. He said the finding and the regulations that stemmed from it “cost Americans a lot of money.”
The formal announcement will come on Tuesday at a truck dealership in Indianapolis, according to a public schedule issued by the Indiana Governor, Mike Braun, who is expected to participate.
Molly Vaseliou, Mr. Zeldin’s spokeswoman, did not respond to requests for comment.
Without the endangerment finding, the E.P.A. would be left with no authority under the Clean Air Act to regulate the greenhouse gas emissions that are accumulating in the atmosphere from the burning of fossil fuels, leading to rising seas, fiercer storms, more deadly heat waves and other extreme weather events.
The proposal would be President Trump’s most significant step yet to derail federal climate efforts. It marks a notable shift in the administration’s position from one that had downplayed the threat of global warming to one that essentially flatly denies the overwhelming scientific evidence of climate change.
In recent weeks, the Trump administration has also moved to scrap restrictions on pollution from power plants, halt key measurements of greenhouse gases in the atmosphere and delay approvals of wind and solar energy projects on federal lands.
Details of the proposal, reviewed by The New York Times, showed that the E.P.A. would argue that, in 2009, when the endangerment finding was put in place during the Obama administration, the agency overstepped its legal authority by finding that greenhouse gas emissions endanger the public welfare.
The E.P.A. also is expected to assert that greenhouse gases from cars on American roads do not contribute significantly to climate change because they are a small share of global emissions, and that eliminating the emissions would have no meaningful effect on public health and welfare. But, according to the draft details, the agency will argue that regulating climate pollution will cause harm, because it would lead to higher prices and fewer choices for car buyers.
Many environmental activists and lawyers criticized those arguments, noting that transportation is the largest source of greenhouse gases in the United States. If the U.S. motor-vehicle sector were a country, it would be the fourth-largest emitter of greenhouse gases in the world, according to the E.P.A.’s own data.
“If vehicle emissions don’t pass muster as a contribution to climate change, it’s hard to imagine what would,” said Dena Adler, a senior attorney at the Institute for Policy Integrity at New York University School of Law.
Dan Becker, who leads transportation policy for the Center for Biological Diversity, an environmental group, called the E.P.A. proposal a “cynical one-two punch” that will lead to more gasoline-burning vehicles on the road and fewer tools to reduce tailpipe pollution. He said that the auto-emissions rules being rescinded were projected to prevent 7 billion metric tons of emissions from entering the atmosphere while saving the average American driver about $6,000 in fuel and maintenance over the lifetime of vehicles built under the standards.
“The E.P.A. is revoking the biggest single step any nation has taken to save oil, save consumers money at the pump and combat global warming,” Mr. Becker said.
The administration’s plan has its backers. Daren Bakst, who directs the Center for Energy and Environment at the Competitive Enterprise Institute, a free-market research organization, said, “It is unreasonable to claim that pollutants contribute to endangerment if emissions are de minimis.”
Representatives for the Alliance for Automotive Innovation, a lobbying group for most major carmakers, did not immediately respond to a request for comment. John Bozzella, the group’s chief executive, said in March that the Biden administration’s auto emissions rules would be “extremely challenging to achieve” because not enough people were buying electric vehicles.
While the Chamber of Commerce and fossil fuel groups had fought the endangerment finding when it was first written, none have been clamoring in recent years for its reversal. This year Marty Durbin, who leads the chamber’s energy institute, called the finding “settled law” and said his group, which is a major business lobbying organization, was not seeking its repeal.