In a move widely anticipated in some respects since the first Trump presidency, the administration Thursday took its most consequential action to end the federal fight against climate change.
The Environmental Protection Agency, EPA, issued its final rule to revoke its own determination that required it to regulate greenhouse gas emissions. Those emissions are known to cause the global warming that has led to the profound climate changes occurring all over the world.
The repeal of what is known as the “endangerment finding” effectively leaves the U.S. standing nearly alone as a nation arguably denying climate change as its national policy, taking minimal action to stop it, and scrubbing it from nearly all aspects of government despite clear science that shows climate change is occurring and has extreme impacts.
The announcement was made Thursday afternoon by President Donald Trump, who has repeatedly referred to climate change as a hoax, and EPA Administrator Lee Zeldin.
“Today, the Trump EPA has finalized the single largest act of deregulation in the history of the United States of America, referred to by some as the holy grail of federal regulatory overreach, the 2009 Obama EPA endangerment finding is now eliminated,” Zeldin said.
And as he has done in the past, Trump called the finding a scam and “a disastrous Obama-era policy that severely damaged the American auto industry and massively drove up prices for American consumers.”
The endangerment finding references a 2007 U.S. Supreme Court ruling — Massachusetts v. EPA — that paved the way for EPA to regulate greenhouse gas emissions in motor vehicles in addition to the standard pollutants it had been regulating under the Clean Air Act since it came into its modern existence in 1970.
The Supreme Court affirmed the Act’s language, which says that the EPA is required to regulate any air pollutants if the administrator finds they “cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare.”
Two years later, the administrator made the finding based on scientific investigation, and six greenhouse gases, the best known of which are carbon dioxide and methane, have been regulated as pollutants since. It has also been used a guidepost for other emitting industries.
Thursday’s announcement was couched in terms of cost. The administration is claiming elimination of endangerment will save $1.3 trillion and about $2,400 on new vehicles.
Pushback was instantaneous
“The next step is now the legal fight in court,” said Connecticut Attorney General William Tong, who is now also the president of the National Association of Attorneys General.
“Over and over again, we see Donald Trump siding with Big Oil. He wants to sell out future generations of Americans for short-term profits for fossil fuel companies and the world’s biggest polluters. But we are going to stop him,” Tong said. “We will be in this fight for as long as it takes.”
The Natural Resources Defense Council is headed there too.
“This cynical and devastating action by the Trump EPA will not go forward without a fight. We will see them in court — and we will win,” said Manish Bapna, president and CEO of NRDC.
“The Trump administration has made it clear they do not care about the impacts greenhouse gas emissions have on the health of our communities, especially our children, seniors, and vulnerable populations,” said Gov. Ned Lamont. “We will fight this decision, just like we have done every time this administration has threatened the health and prosperity of the people of Connecticut.”
The endangerment finding was specifically targeted for reconsideration in the conservative government playbook Project 2025. In March, Zeldin announced it was under review, and in July, EPA announced it wanted endangerment gone, calling it the “largest deregulatory action in the history of America.”
Much of the justification for repeal was derived from a climate report by the Department of Energy, conducted in secret by five known climate skeptics, if not outright deniers, handpicked by Energy Secretary Chris Wright. Last month, a U.S. District Court in Massachusetts determined the report process was illegal.
Many have pointed out that the evidence of climate change has only grown stronger over time with annual heat records being set and broken year after year and weather extremes from hurricanes to flooding to wildfires exacerbated by climate change.
Connecticut’s air
For Connecticut, one of the biggest concerns is air quality, with greenhouses gases and other pollutants from motor vehicles as the worst offenders.
“The evidence is even clearer now than it was in 2009 — greenhouse gases pollute the air and contribute significantly to poor air quality,” said Katie Dykes, Connecticut commissioner of the Department of Energy and Environmental Protection. “Connecticut suffers from some of the worst air quality in the United States, and greenhouse gas emissions, including from vehicles, contribute to air pollution that exacerbates respiratory illness, resulting in tens of millions of dollars spent on related health care costs in our state every year. Walking away from protecting the environment and public health will cost us. This reckless action puts us at greater risk for climate-related impacts, such as the dangerous and costly extreme weather events we’ve experienced in recent years, making Connecticut less safe.”
In advance of the endangerment action, Trump last June rescinded the motor vehicle waivers California is allowed to request for stricter emission standards than the federal government requires. California’s most recent ones had been aimed at a zero vehicle emissions standard in the next 10 years. At the same time, Trump loosened federal emission standards, and the federal government is no longer collecting fines when emission standards are exceeded.
Even before that, Connecticut struggled to meet its long-term targets for cutting greenhouse gas emissions.
In 2020, the state was able to meet its initial 20% reduction target as the pandemic kept many drivers off the road. Since then, overall emissions have ticked upward even though they remain below pre-pandemic levels.
Without additional actions from the state and federal government — including a reversal of some of Trump-era cuts to clean energy programs — Connecticut is on pace to cut emissions by just 44% by 2050, according to a draft report released last month by DEEP. Such a reduction would fall far short of the net-zero target signed into law by Gov. Ned Lamont last year.
“Emissions are expected to decline across major sectors, but clean technologies are not being adopted fast enough to meet these targets,” the report found.
The report also noted that while Connecticut has implemented its own programs to reduce emissions, those efforts cannot make up for the sweeping loss of federal grants, tax credits and regulatory rollbacks such as the repeal of the endangerment finding.
“Unfortunately, in 2025, the federal government has taken steps to reverse emissions reduction progress, putting the health and safety of Connecticut residents at risk, and undermining the reliability and affordability of the region’s electricity supply,” the report stated.
The legal options
Battles have raged since 2007 over whether the Supreme Court decided the original case properly.
Three of the four justices who voted against it originally are still on the court: Chief Justice John Roberts, Clarence Thomas and Samuel Alito. None of the five justices who voted for it remain, and three more conservative justices are now in place.
There is little doubt that the EPA’s repeal is headed back to the high court. Aside from the super-majority of conservatives, the legal and environmental landscapes have changed dramatically in the last 20 years.
The court has issued a number of rulings that have effectively closed off avenues for challenges. The Chevron decision in June of 2024 and in 2022 the court’s use of the so-called major questions doctrine both generally now restrict what agencies like the EPA and the Energy Department can do without specific direction from Congress.
“It’s changed everything,” said Tong, not long after Trump was elected in 2024. “It’s hard to overstate how profound this change is. It essentially overturns the whole apple cart of regulatory infrastructure in this country.”
And indeed, Thursday’s announcement seemed to lean into the earlier court rulings. “For years, unelected bureaucrats twisted the Clean Air Act into something it was never meant to be,” Zeldin said. “We looked at the Clean Air Act; we looked at what the highest court in the land had said, and we used a very simple metric: if Congress didn’t authorize it, EPA shouldn’t be doing it. Congress never voted for these climate mandates.
“If Congress wants EPA to regulate the heck out of greenhouse gases emitted from motor vehicles, then Congress can clearly make that the law, which they haven’t done.”
But Dan Esty, Connecticut’s first DEEP commissioner and now the Hillhouse professor at Yale serving in both Yale Law School and the School of the Environment, points out that the original Clean Air Act left room for additional gases to be considered if needed and that the 2007 Supreme Court indeed ruled that EPA was properly taking up greenhouse gases.
He also said the fact the repeal justification did not cite a scientific basis could be a legal vulnerability for the Trump administration.
“There was an extensive scientific review undertaken prior to the 2009 endangerment finding being issued,” he said. “[The Trump administration is] not free to ignore the science and say ‘we have a different view.’ They actually have to grapple with the science, and should they not do so in a serious way, then there would be a charge, and there will be a case brought in this regard that the decision is arbitrary and capricious.”
Esty also said there could be an unintended and ironic consequence to getting rid of the endangerment finding. The Supreme Court has ruled that state level Clean Air Act tort cases are not allowed because of the existing federal climate change law. But if that goes away, it could open every state to such lawsuits. “I think the argument that there now may be state level tort claims that can be brought could turn out to be a much more powerful tool for addressing climate change than the struggle that it’s been to do things in a serious way under the Clean Air Act through the federal regulatory process,” he said.
Gina McCarthy, EPA administrator in the Obama administration, White House national climate advisor and a former environmental chief in Connecticut, who now serves as chair of the climate group America Is All In, said in a statement: “For more than 15 years, EPA has had a clear scientific and legal obligation to regulate greenhouse gases, and the evidence has only grown stronger as their health and environmental hazards have become impossible to ignore. State, city, community, university, and business leaders across the country will not let this Administration’s dangerous decisions stop them from following the science, driving down pollution, and protecting public health.”
It’s only the latest move
The legal landscape is not the only change faced by those seeking to keep endangerment intact. In the year since Trump took office again, the administration has instituted a torrent of environmental rollbacks.
They have scrubbed climate change from almost any mention in public documentation and ended climate-related units in most departments. Funding and other support for renewables, especially solar and wind, are gone or destined to disappear in the next year. Trump has all but killed offshore wind, even trying to halt nearly complete construction projects, including Connecticut’s. Judges have restarted all of them, a move the administration said Wednesday it plans to appeal.
Fossil fuel use is being ramped up, including forcing old and unprofitable coal units to operate beyond their planned closures. Just this week, Trump ordered the Pentagon to buy more coal-fired power. Oil and gas drilling is now allowed on land and sea areas previously off-limits. Air quality regulations and programs are loosening their restrictions.
And any kind of environmental justice program, including those geared to climate change concerns, have been cancelled.
The compounding effect, with the potential loss of the endangerment finding on top, has arguably made the whole greater than the sum of its parts.
“It’s important to see (the endangerment repeal) in the context of the almost relentless assault on the capacity of the government to confront the climate challenge,” said Gerald Torres, the Dolores Huerta and Wilma Mankiller professor of environmental justice at the Yale School of the Environment. He said the cuts to FEMA, for instance, have made Americans less capable of responding to the climate challenges and that “the already vulnerable groups are going to bear a greater share of the burden.”
“The elimination of the endangerment finding — it’s the keystone for the other regulations on greenhouse gases. I don’t want to minimize the importance of it, but it all has to be taken in the context of a broader attempt to turn away from the challenges which we know are facing us.”
While both Trump and Zeldin repeatedly noted the endangerment repeal in cost-saving terms — as they stood beside big signs that did the same — neither spoke of the well-documented avoided costs of environmental and climate actions including lower health care costs, less missed work due to the health impacts from climate change such as extreme heat, and fewer climate-exacerbated extreme weather events and their costs.
Gary Yohe, an environmental economist, retired from Wesleyan University, said the Trump administration, while citing cost, has continued to assume the cost of climate, known as the social cost of carbon, is zero.
“It’s not being done comprehensively. It is not taking into account the human value. It’s not taking into account the employment opportunities that the infrastructure and the manufacturing provided within the United States economy,” said Yohe, who worked on four of the climate reports produced by the Intergovernmental Panel on Climate Change and was the vice chair of the third National Climate Assessment during the Obama administration. “They cherry-picked on the climate research, irresponsibly and deceitfully, and they cherry-picked on their cost analysis as well.”
“While this isn’t a surprise, it is still a betrayal of every family across the country,” said Kate Sinding Daly, senior vice president for law and policy at the New England based Conservation Law Foundation. “The Trump administration is trying to negate basic science. Fossil fuels cost households hundreds of dollars a year in energy bills and billions more in extreme weather repairs. And they cost us our lives and our planet. Now that the EPA has set this process in motion, we are prepared to stand together, challenge this reckless, profits-over-people decision, and hold the administration accountable by every means necessary.”
John Moritz and Jan Ellen Spiegel are reporters for the Connecticut Mirror. Copyright 2026 @ CT Mirror (ctmirror.org).