What the EPA’s “endangerment finding” is and why it’s being challenged
Getting rid of the justification for greenhouse gas regulations won’t be easy.
Credit: Mario Tama/Getty Images
A document that was first issued in 2009 would seem an unlikely candidate for making news in 2025. Yet the past few weeks have seen a steady stream of articles about an analysis first issued by the Environmental Protection Agency (EPA) in the early years of Obama’s first term: the endangerment finding on greenhouse gases.
The basics of the document are almost mundane: Greenhouse gases are warming the climate, and this will have negative consequences for US citizens. But it took a Supreme Court decision to get written in the first place, and it has played a role in every attempt by the EPA to regulate greenhouse gas emissions across multiple administrations. And, while the first Trump administration left it in place, the press reports we’re seeing suggest that an attempt will be made to eliminate it in the near future.
The only problem: The science in which the endangerment finding is based on is so solid that any ensuing court case will likely leave its opponents worse off in the long run, which is likely why the earlier Trump administration didn’t challenge it.
Get comfortable, because the story dates all the way back to the first Bush administration.
A bit of history
One of the goals of the US’s Clean Air Act, first passed in 1963, is to “address the public health and welfare risks posed by certain widespread air pollutants.” By the end of the last century, it was becoming increasingly clear that greenhouse gases fit that definition. While they weren’t necessarily directly harmful to the people inhaling them—our lungs are constantly being filled with carbon dioxide, after all—the downstream effects of the warming they caused could certainly impact human health and welfare. But, with the federal government taking no actions during George W. Bush’s time in office, a group of states and cities sued to force the EPA’s hand.
That suit eventually reached the Supreme Court in the form of Massachusetts v. EPA, which led to a ruling in 2007 determining that the Clean Air Act required the EPA to perform an analysis of the dangers posed by greenhouse gases. That analysis was done by late 2007, but the Bush administration simply ignored it for the remaining year it had in office. (It was eventually released after Bush left office.)
That left the Obama-era EPA to reach essentially the same conclusions that the Bush administration had: greenhouse gases are warming the planet. And that will have various impacts—sea-level rise, dangerous heat, damage to agriculture and forestry, and more.
That conclusion compelled the EPA to formulate regulations to limit the emission of greenhouse gases from power plants. Obama’s EPA did just that, but came late enough to still be tied up in courts by the time his term ended. The regulations were also formulated before the plunge in the cost of renewable power sources, which have since led to a drop in carbon emissions that have far outpaced what the EPA’s rules intended to accomplish.
The first Trump administration formulated alternative rules that also ended up in court for being an insufficient response to the conclusions of the endangerment finding, which ultimately led the Biden administration to start formulating a new set of rules. And at that point, the Supreme Court decided to step in and rule on the Obama rules, even though everyone knew they would never go into effect.
The court indicated that the EPA needed to regulate each power plant individually, rather than regulating the wider grid, which sent the Biden administration back to the drawing board. Its attempts at crafting regulations were also in court when Trump returned to office.
There were a couple of notable aspects to that last case, West Virginia v. EPA, which hinged on the fact that Congress had never explicitly indicated that it wanted to see greenhouse gases regulated. Congress responded by ensuring that the Inflation Reduction Act’s energy-focused components specifically mentioned that these were intended to limit carbon emissions, eliminating one potential roadblock. The other thing is that, in this and other court cases, the Supreme Court could have simply overturned Massachusetts v. EPA, the case that put greenhouse gases within the regulatory framework of the Clean Air Act. Yet a court that has shown a great enthusiasm for overturning precedent didn’t do so.
Nothing dangerous?
So, in the 15 years since the EPA initially released its endangerment findings, they’ve resulted in no regulations whatsoever. But, as long as they existed, the EPA is required to at least attempt to regulate them. So, getting rid of the endangerment findings would seem like the obvious thing for an administration led by a president who repeatedly calls climate change a hoax. And there were figures within the first Trump administration who argued in favor of that.
So why didn’t it happen?
That was never clear, but I’d suggest at least some members of the first Trump administration were realistic about the likely results. The effort to contest the endangerment finding was pushed by people who largely reject the vast body of scientific evidence that indicates that greenhouse gases are warming the climate. And, if anything, the evidence had gotten more decisive in the years between the initial endangerment finding and Trump’s inauguration. I expect that their effort was blocked by people who knew that it would fail in the courts and likely leave behind precedents that made future regulatory efforts easier.
This interpretation is supported by the fact that the Trump-era EPA received a number of formal petitions to revisit the endangerment finding. Having read a few (something you should not do), they are uniformly awful. References to supposed peer-reviewed “papers” turn out to be little more than PDFs hosted on a WordPress site. Other arguments are based on information contained in the proceedings of a conference organized by an anti-science think tank. The Trump administration rejected them all with minimal comment the day before Biden’s inauguration.
Biden’s EPA went back and made detailed criticisms of each of them if you want to see just how laughable the arguments against mainstream science were at the time. And, since then, we’ve experienced a few years of temperatures that are so high they’ve surprised many climate scientists.
Unrealistic
But the new head of the EPA is apparently anything but a realist, and multiple reports have indicated he’s asking to be given the opportunity to go ahead and redo the endangerment finding. A more recent report suggests two possibilities. One is to recruit scientists from the fringes to produce a misleading report and roll the dice on getting a sympathetic judge who will overlook the obvious flaws. The other would be to argue that any climate change that happens will have net benefits to the US.
That latter approach would run into the problem that we’ve gotten increasingly sophisticated at doing analyses that attribute the impact of climate change on the individual weather disasters that do harm the welfare of citizens of the US. While it might have been possible to make a case for uncertainty here a decade ago, that window has been largely closed by the scientific community.
Even if all of these efforts fail, it will be entirely possible for the EPA to construct greenhouse gas regulations that accomplish nothing and get tied up in court for the remainder of Trump’s term. But a court case could show just how laughably bad the positions staked out by climate contrarians are (and, by extension, the position of the president himself). There’s a small chance that the resulting court cases will result in a legal record that will make it that much harder to accept the sorts of minimalist regulations that Trump proposed in his first term.
Which is probably why this approach was rejected the first time around.
John is Ars Technica’s science editor. He has a Bachelor of Arts in Biochemistry from Columbia University, and a Ph.D. in Molecular and Cell Biology from the University of California, Berkeley. When physically separated from his keyboard, he tends to seek out a bicycle, or a scenic location for communing with his hiking boots.
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