As it has said for months it would do, the Environmental Protection Agency Tuesday began the process of overturning its key tool for fighting climate change. 

Known by its shorthand — the endangerment finding — it refers to a 2007 U.S. Supreme Court ruling under which the EPA began regulating greenhouse gas emissions in addition to the standard pollutants it had been regulating under the Clean Air Act since 1970. The finding said that the EPA had to regulate any air pollutant found to endanger “public health or welfare.”

The announcement, made by EPA Administrator Lee Zeldin at an event in Indiana, disputes how the EPA administered some of the original court decision.

Repealing the endangerment finding “will be the largest deregulatory action in the history of America,” Zeldin said on the Ruthless podcast ahead of the official announcement.

“There are people who, in the name of climate change, are willing to bankrupt the country,” Zeldin said. “They created this endangerment finding and then they are able to put all these regulations on vehicles, on airplanes, on stationary sources, to basically regulate out of existence, in many cases, a lot of segments of our economy. And it cost Americans a lot of money.”

The EPA proposal must go though a lengthy review process, including public comment, before it is finalized, likely next year. Environmental groups are likely to challenge the rule change in court.

Zeldin called for a rewrite of the endangerment finding in March as part of a series of environmental rollbacks announced at the same time in what he said was “the greatest day of deregulation in American history.” A total of 31 key environmental rules on topics from clean air to clean water and climate change would be rolled back or repealed under Zeldin’s plan.

He singled out the endangerment finding as “the Holy Grail of the climate change religion” and said he was thrilled to end it “as the EPA does its part to usher in the Golden Age of American success.”

While the EPA’s decision does not alter Connecticut’s own efforts to slash greenhouse gas emissions, it is likely to make it harder for the state to meet its goals.

Exhaust from cars and trucks makes up by far the largest source of greenhouse gas emissions in Connecticut, according to the state Department of Energy and Environmental Protection, followed by emissions from residential and commercial buildings.

“Rolling back these protections puts our communities — especially our children, seniors, and vulnerable populations — at greater risk from the harmful effects of greenhouse gas pollution,” said Gov. Ned Lamont. “Connecticut has a proud, bipartisan history of standing up for environmental safeguards, and we won’t sit by while decades of progress are dismantled.”

Connecticut Attorney General William Tong, who has filed for Connecticut to join a number of lawsuits against other Trump measures and cutbacks, similarly argued state officials would not let “Trump and Zeldin do this without a fight.”

Tailpipe emission limits also targeted

The EPA also seeks to rescind limits on tailpipe greenhouse gas emissions that were designed to encourage automakers to build and sell more electric vehicles. The transportation sector is the largest source of greenhouse gas emissions in the United States.

Environmental groups said Zeldin’s action denies reality as weather disasters exacerbated by climate change continue in the U.S. and around the world.

“As Americans reel from deadly floods and heat waves, the Trump administration is trying to argue that the emissions turbocharging these disasters are not a threat,” said Christy Goldfuss, executive director of the Natural Resources Defense Council. “It boggles the mind and endangers the nation’s safety and welfare.”

Under Zeldin and Trump, “the EPA wants to shirk its responsibility to protect us from climate pollution, but science and the law say otherwise,” she added. “If EPA finalizes this illegal and cynical approach, we will see them in court.”

Gina McCarthy, who led Connecticut’s environment department and then served as the air bureau chief and EPA administrator for President Barack Obama as well as a national climate advisor to President Joe Biden, said in a statement: “Trump’s EPA is trying every trick in the book to deny and avoid their mission to protect people and the environment from the ravages of unchecked climate pollution. Instead of doing their job, this EPA is putting the safety of our loved ones at risk while ratcheting up grid instability, energy bills, and disaster costs.” 

McCarthy is now managing co-chair of the climate activist group America Is All In.

The New England based Conservation Law Foundation, which specializes in legal action on behalf of environmental issues, also issued a statement.

“President Trump is once again siding with Big Oil and Gas over our health,” said Kate Sinding Daly, the group’s senior vice president for law and policy. “It’s a scientific fact: fossil fuel pollution is deadly. But President Trump is trying to erase that truth. His administration is attacking the EPA’s legal backbone that that gives the agency power to regulate climate-warming emissions and the danger they pose. Gutting it would strip away vital protections, lead to dirtier air, and cost lives.” 

Motor vehicle pollution is known to worsen asthma and many other health, lung and heart problems. It tends to disproportionately impact at-risk communities already suffering from higher pollution and the effects of the more intense storms caused by climate change.

“Let’s be clear: this isn’t just wrong — it’s an attack on public health, basic science, and families who just want clean air and a livable future. And all to let polluters keep profiting while the rest of us choke on the consequences,” Sinding Daly said.  

Three former EPA leaders have also criticized Zeldin, saying his March announcement targeting the endangerment finding and other rules imperiled the lives of millions of Americans and abandoned the agency’s dual mission to protect the environment and human health.

“If there’s an endangerment finding to be found anywhere, it should be found on this administration because what they’re doing is so contrary to what the Environmental Protection Agency is about,” Christine Todd Whitman, who led EPA under Republican President George W. Bush, said after Zeldin’s plan was made public.

The EPA proposal follows an executive order from Trump that directed the agency to submit a report “on the legality and continuing applicability” of the endangerment finding, which came directly from Project 2025, released during the 2024 presidential campaign.

Conservatives and some congressional Republicans hailed the initial plan, calling it a way to undo economically damaging rules to regulate greenhouse gases.

But environmental groups, legal experts and Democrats said any attempt to repeal or roll back the endangerment finding would be an uphill task with slim chance of success. The finding came two years after a 2007 Supreme Court ruling holding that the EPA has authority to regulate greenhouse gases as air pollutants under the Clean Air Act.

Dan Esty, who is the Hillhouse professor at Yale serving in both Yale Law School and the School of the Environment, said through the regulation provided by the endangerment finding, the U.S was moving towards a clean energy future and greenhouse gas emissions were going down.

“This disrupts that process, and it puts the United States at odds with virtually every other country in the world,” said Esty, who was Connecticut’s first commissioner of the Department of Energy and Environmental Protection, serving from 2011 to 2014.

He also noted that the EPA action is in sharp contrast to the International Court of Justice opinion last week, which declared that any number of elements of this regulatory package could be seen as in violation of international law and subject the United States and potentially entities operating within it to legal consequences around the world.

Esty’s legal assessment is that the administration will face significant difficulty proving that the evidence does not suggest that there’s a problem that needs to be addressed on the Clean Air Act. He said the tactic seems to be to shift from focusing on the science to focusing on the cost. But he called the trillion dollar price tag floated by Zeldin “a fictional number picked out of the air and has no bearing to the reality on the ground.”

“They face substantial challenges in meeting the basic test under the Administrative Procedure Act, which is where the litigation will go. And that is, are they acting in a manner that is arbitrary and capricious?” he said. “They have to demonstrate with substantial evidence that the direction they want to go is justified. And I do not think they will be able to meet that legal test.”

Charles Rothenberger is an attorney and director of Connecticut government relations at Save the Sound. He said the endangerment finding is a scientific finding, not a policy determination. “You can’t just willy nilly reverse yourself as an agency and say, ‘well, what we believed yesterday, we don’t believe today.’ There has to be substantial evidence to support that, and a clear and compelling reason to do that. So what the administration is bringing to the table, really is a policy preference,” he said.

Passing court muster could be an issue

David Doniger, a climate expert at the NRDC, accused Trump’s Republican administration of using potential repeal of the endangerment finding as a “kill shot” that would allow him to make all climate regulations invalid. If finalized, repeal of the endangerment finding would erase current limits on greenhouse gas pollution from cars, factories, power plants and other sources and could prevent future administrations from proposing rules to tackle climate change.

“The Endangerment Finding is the legal foundation that underpins vital protections for millions of people from the severe threats of climate change, and the Clean Car and Truck Standards are among the most important and effective protections to address the largest U.S. source of climate-causing pollution,” said Peter Zalzal, associate vice president of the Environmental Defense Fund.

“Attacking these safeguards is manifestly inconsistent with EPA’s responsibility to protect Americans’ health and well-being,” he said. “It is callous, dangerous and a breach of our government’s responsibility to protect the American people from this devastating pollution.”

Conrad Schneider, a senior director at the Clean Air Task Force, said the Trump administration “is using pollution regulations as a scapegoat in its flawed approach to energy affordability” and reliability.

He and other advocates “are dismayed that an administration that claims it cares about cleaner, healthier and safer air is seeking to dismantle the very protections that are required for those conditions,” Schneider said.

“This decision is both legally indefensible and morally bankrupt,” said Joseph Goffman, former assistant administrator of EPA’s Office of Air and Radiation. “The Supreme Court made clear that EPA cannot ignore science or evade its responsibilities under the Clean Air Act. By walking away from the endangerment finding, EPA has not only broken with precedent; it has broken with reality.”

CT Mirror reporter John Moritz contributed to this story.