In Game-Changing Climate Rollback, E.P.A. Aims to Kill a Bedrock Scientific Finding

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 at a truck dealership in Indianapolis, 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.

“The proposal would, if finalized, amount to the largest deregulatory action in the history of the United States,” Mr. Zeldin said. He said the proposal would also erase limits on greenhouse gas emissions from cars and trucks on the nation’s roads.

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.

The proposal is President Trump’s most consequential 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.

It would not only reverse current regulations, but, if the move is upheld in court, it could make it significantly harder for future administrations to rein in climate pollution from the burning of coal, oil and gas.

Without the United States working to reduce emissions, it becomes far tougher for the world to collectively prevent average global temperatures from rising by more than 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, above preindustrial levels. That is the threshold beyond which climate scientists say there is significantly greater risk from increasingly destructive storms, droughts, wildfires and heat waves, as well as from species extinction.

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.

“Today’s E.P.A. announcement ignores the blindingly obvious reality of the climate crisis and sidelines the E.P.A.’s own scientists and lawyers in favor of the interests and profits of the fossil fuel industry,” former Vice President Al Gore said in a statement.

To justify the proposal, the E.P.A. cited a report that the Energy Department commissioned from five scientists known for their rejection of the overwhelming scientific consensus on climate change, namely that it is being driven by the burning of fossil fuels, which releases greenhouse gases into the atmosphere.

The New York Times first reported that the Energy Department had hired these scientists, including Steven E. Koonin, a physicist and author of a best-selling book that calls climate science “unsettled,” and John Christy, an atmospheric scientist who doubts the extent to which human activity has caused global warming.

In their report, the scientists criticized the computer models used to predict climate change, saying they tend to overestimate warming. They also wrote that carbon dioxide, the most prevalent greenhouse gas in the atmosphere, has positive effects by helping plants grow and increasing agricultural productivity. And they asserted that overall, government climate regulations have a limited effect on global temperature rise.

The E.P.A. echoed this last argument in the proposed rule, saying greenhouse gases from cars on American roads do not contribute significantly to climate change because they are a small share of global emissions. Reducing these emissions to zero “would not have a scientifically measurable impact” on global climate trends or on public health and welfare, the agency said. Instead, the agency said, climate regulations are what pose the true threat to public health and welfare, because they increase the price of new vehicles and leave 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.”

Mike Braun, the governor of Indiana, said at the event in Indianapolis that the Biden administration’s vehicle emissions rules had burdened the auto industry in the state. “As a lifelong entrepreneur for 37 years actually in the automotive business, I think I know a thing or two about it, and you can count on Indiana being for common sense and reining in government,” he said.

John Bozzella, chief executive of the Alliance for Automotive Innovation, a lobbying group for most major carmakers, said in a statement that he was still reviewing the E.P.A.’s announcement. “At the same time, there’s no question the vehicle emissions regulations finalized under the previous administration aren’t achievable and should be revised to reflect current market conditions, to keep the auto industry in America competitive,” he said.

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.

“I’m not aware of anyone in industry who has been pushing for it,” said Jeffrey Holmstead, an energy attorney with the law firm Bracewell who served in the E.P.A. during the administration of the first President George Bush and, later, that of President George W. Bush.

The plan to eliminate the endangerment finding showcases the political evolution of Mr. Zeldin, who for years took moderate positions on climate change and other environmental issues.

A former congressman from a coastal community on Long Island that is struggling with rising sea levels linked to global warming, Mr. Zeldin once joined a bipartisan caucus to address climate change. In 2019 he broke with fellow Republicans to vote against an amendment that would have prohibited the E.P.A. from reducing greenhouse gas emissions.

An ally of Mr. Trump who prominently defended him during House impeachment hearings, Mr. Zeldin moved to the right on energy and other issues during his unsuccessful bid for governor of New York in 2022. Just weeks after his nomination to lead the E.P.A., Mr. Zeldin declared that he would be “driving a dagger through the heart of climate-change religion” by repealing regulations on greenhouse gas emissions

“There are people who, in the name of climate change, are willing to bankrupt the country,” Mr. Zeldin said on the conservative podcast “Ruthless” earlier on Tuesday. One of the co-hosts of the program called the endangerment finding “the left’s tent pole to begin the whole climate grift,” to which Mr. Zeldin agreed.

The proposed repeal of the endangerment finding is all but certain to draw legal challenges, and David Doniger, a senior attorney at the Natural Resources Defense Council, an environmental group, said he expected that it would eventually be struck down in court. He noted that climate science has advanced significantly since 2009, when the finding was issued.

After the proposal is published in the Federal Register, the E.P.A. will solicit comments from the public for 45 days, Mr. Zeldin said. The agency will then finalize the rule, most likely in the next year.