Climate science skeptics emboldened by a second Trump administration are eager to strike down a scientific finding that bolsters U.S. climate action.
But repealing the landmark decree that greenhouse gases threaten public health and welfare may prove a tough lift — even with a Supreme Court that has shown a predilection for paring back environmental regulations.
The 2009 determination by the Obama-era EPA that six greenhouse gases — including carbon dioxide and methane — threaten human health and by law must be regulated has long been a conservative target.
A reversal of the decision headlines a wish list for climate rollbacks that’s been delivered to Trump’s transition team, alongside again pulling the United States out of the Paris climate accord.
“It is absolutely on the chopping block, the whole climate agenda is on the chopping block,” said Steve Milloy, a lawyer who served on Trump’s EPA transition team in 2016 and considers the endangerment finding the “source of the evil” when it comes to U.S. climate policy. “There are plans to do everything we’ve ever dreamed of.”
Still, conservatives were disappointed the first time around when the Trump administration’s own EPA lawyers rejected a petition to reconsider the endangerment finding — on Trump’s last day in office in 2021.
Milloy says things will be different this time under Trump’s nominee to lead the agency, former Republican Rep. Lee Zeldin of New York.
“It was sort of botched in Trump 1, they didn’t get the memo and dropped the ball,” Milloy said. “I think that with Trump 2.0, we’ve all learned a lot more.”
Conservatives this time around also have a pair of Supreme Court decisions that some legal analysts say could broadly imperil climate law.
In West Virginia v. EPA, the court in 2022 struck down an Obama-era rule for power plants and highlighted the “major questions” doctrine, which says Congress must clearly give agencies the authority to tackle economically and politically significant issues.
And earlier this year, the court in Loper Bright v. Raimondo overturned the 40-year-old Chevron doctrine, which had instructed judges to give federal agencies leeway to interpret ambiguous laws.
“I think conservatives want to use these new doctrines to put a lot of old interpretations back into play,” said Sam Sankar, head of litigation at Earthjustice.
He added that some groups may hope in particular to revisit Massachusetts v. EPA, the 2007 Supreme Court case that established the agency’s authority to regulate greenhouse gases and teed up the endangerment finding.
Other environmental attorneys, however, noted Loper Bright in particular is not relevant to the endangerment finding because Chevron had directed courts on how to defer to an agency’s reading of a statute.
“The demise of Chevron has no legal relationship to the endangerment finding,” said Lisa Heinzerling, a Georgetown Law professor. “The endangerment finding isn’t an interpretation of the Clean Air Act or any other statute; it’s a factual finding based on scientific evidence.”
Milloy said the Supreme Court rulings could be helpful. But he argued the administration may not even need to revisit Massachusetts v EPA. Instead, the administration could persuade the agency to scrap the finding under the Administrative Procedures Act.
“Who knows what the legal perambulations will be,” he said. “But I am looking forward to Administrator Zeldin starting the process.”
Environmental attorneys, however, contend the science has become only more robust since 2009.
“It’s one thing for Trump to say climate change is a hoax. It’s another thing for an agency to try to prove that in the Federal Register, in an official decision that’s supposed to survive inspection,” said David Doniger, who specializes in the Clean Air Act as senior attorney at the Natural Resources Defense Council.
“This stuff is tangible now and more climate fueled disasters will happen on his watch,” Doniger said. “They have no chance in getting the courts to uphold them if they were to reverse a fundamental science finding.”
Doniger said he has no doubt that critics will try. But he noted the finding has withstood multiple challenges, including by the U.S. Court of Appeals for the District of Columbia Circuit in 2012.
The D.C. circuit panel at the time included one of the staunchest conservatives on the court, Judge David Sentelle, who was nominated by President Ronald Reagan to the seat that was left open when Judge Antonin Scalia was appointed to the Supreme Court.
Doniger noted the Supreme Court has shown little interest in getting involved.
The high court as recently as December 2023 turned down a request to review the finding. Two conservative groups, the Concerned Household Electricity Consumers Council and the FAIR Energy Foundation had argued that EPA’s finding created a “regulatory tsunami” and remains the “most economically significant regulation on the federal books today.”
The groups invoked West Virginia v. EPA, but lost in the D.C. Circuit — which concluded that the groups had failed to demonstrate how they had been harmed by the finding.
The Trump transition team did not respond to a request for comment, nor did several conservative groups that have unsuccessfully challenged the finding.
The Competitive Enterprise Institute, which has challenged the endangerment finding in the past, wouldn’t say whether it expects the administration to embrace the effort.
Daren Bakst, a senior fellow and director of the institute’s Center for Energy & Environment, said he expects the administration “to establish a strong legal foundation for whatever they seek to do when it comes to EPA regulations.”
“Beyond repealing many rules, I expect the Trump EPA to pursue many reforms that will improve scientific transparency and integrity, as well as regulatory analysis,” Bakst said in written comments. “The EPA too often acts as if it is the regulator of how we should live our lives, often due to its focus on greenhouse gas regulation, as opposed to ensuring we have a clean environment. That needs to change.”
‘Fool’s errand’
Jeff Holmstead, who helmed EPA’s Office of Air and Radiation in the George W. Bush administration, said he would be surprised if the Trump administration moves ahead, noting that even some conservative judges have noted in opinions that they believe climate change is a serious issue.
“I’m pretty conservative on various regulatory issues, but I think they would waste a ton of time on something that would probably not stand up in court,” Holmstead said.
He noted that Trump’s first EPA administrators — Scott Pruitt and Andrew Wheeler — “were not exactly shrinking violets, and I think that they understood that it would be a fool’s errand.”
That’s despite the fact that a court today may be more likely under West Virginia v EPA to find that regulating carbon emissions under the Clean Air Act is a major question, Holmstead said.
But he added, the Supreme Court has a history of not overruling decisions that deal with statutory interpretations.
Holmstead noted that critics already have identified a number of what he called “crazily expensive” Biden climate initiatives. The incoming administration “is not going to be able to overturn those things if they’re spending all of their time and political capital on trying to overturn the endangerment finding,” he said.
A push also could run afoul of an energy industry that prefers regulatory certainty and is transitioning to cleaner energy, said Sean Donahue, a lawyer representing environmental groups that backed EPA in the most recent challenge to the finding.
“It would associate our government with the most rank denialism and would be an embarrassment,” said Donahue, an attorney at the law firm Donahue & Goldberg. “Companies that operate in parts of the world that are aware of, and taking the science somewhat seriously, would be put in an odd position.”
He noted that a reversal could pose unintended consequences, including giving states such as California greater authority to regulate greenhouse gases.
“You could be sure that the states that actually believe in climate science would do everything in their power to fill the gap,” Donahue said. “The first weeks of Trump’s transition have brought all kinds of surprises, but this would be a real impossible mountain to climb because both the law and the science are particularly imposing.”
