[Here and at the end of this post, a template comment letter is linked for local governments to adapt for their own comments in the Endangerment Finding rule making process.]
On August 1, 2025, the U.S. Environmental Protection Agency (EPA) published its proposed repeal of the “Endangerment Finding,” the scientific and legal predicate for federal rules to limit greenhouse gas (GHG) emissions from vehicles and other sources. The proposed action was billed as “the largest deregulatory action in the history of the United States,” an unverifiable but nonetheless directionally accurate statement. If EPA is successful in fully repealing the Endangerment Finding – something we will not know until the proposal is finalized and likely years of litigation play out – future administrations will face considerable barriers to regulating GHG emissions, if they can regulate at all. The EPA also proposes to repeal all GHG emissions standards for new motor vehicles—an action that would, on its own, have devasting climate consequences given that the transportation sector is the leading source of GHG emissions in the U.S. today.
EPA’s proposals to repeal the Endangerment Finding and the vehicle GHG standards it supports are currently in the administrative rulemaking phase. The rulemaking remains open for public comment through September 22, 2025, and anyone – cities, local elected officials, community groups and individual residents – may submit comment letters.
Participating in the public comment process has three potential benefits. First, public comments can inform EPA’s thinking as it finalizes its rulemaking, influencing revisions to its proposal. In this rulemaking, EPA seems determined to repeal the Endangerment Finding, and local leaders may not be the right stakeholders to convince the agency otherwise. But commenting can still have an impact. Indeed, the second benefit is that public comment letters help build the administrative record, which can then be drawn from by attorneys in the litigation that is sure to follow conclusion of the rulemaking. This is where the local perspective can be particularly useful: when cities, local officials, and community groups share the public health impacts, costs to adapt and respond to extreme weather, and their reliance on federal regulation to bolster their own climate and clean energy goals, groups challenging any eventual repeal of the Endangerment Finding or of the motor vehicles regulations can draw on those submissions to build their cases. And third, submitting a comment letter can be a communications opportunity, a chance for cities to express public support for robust GHG regulations.
This blog post is designed to help local leaders navigate the proposed repeal of the Endangerment Finding and the related GHG standards for motor vehicles. It explains what the Endangerment Finding is, what EPA has proposed, and what’s at stake for local governments and communities if EPA moves forward.
The Endangerment Finding, Explained
In 2009, the EPA made a formal determination that six greenhouse gases – carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) – in combination “may reasonably be anticipated to endanger the public health and welfare of current and future generations.” Referred to as the “Endangerment Finding,” the determination was based on extensive scientific evidence, and followed a 2009 Supreme Court decision in Massachusetts v. EPA, which held that GHGs fall within the definition of air pollution under the Clean Air Act, and thus could be regulated if an Endangerment Finding was made.
EPA’s Endangerment Finding had immediate legal consequence. Under Section 202 of the Clean Air Act, the EPA Administrator is required to promulgate and periodically update regulations “applicable to the emission of any air pollutant from any class or classes of new motor vehicles or new motor vehicle engines, which in his judgment cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare.” The EPA began regulating vehicles for model years starting in 2012.
The Endangerment Finding was later used as the scientific basis for greenhouse gas regulations for power plants and oil and gas wells, both under Section 111 of the Clean Air Act. While the legal mechanics differ for these two regulations, without the Endangerment Finding, EPA would lack the scientific underpinning for them. (It is worth noting that each of these regulations are the subject to their own ongoing repeal processes or efforts to delay compliance).
The Endangerment Finding is the basis for all federal limits on GHG emissions from any source. Without it, EPA cannot regulate GHG emissions from motor vehicles or from power plants, which together account for over 47 percent of all GHG emissions in the United States, and for much higher percentages in GHG emissions in many cities. GHG limits on these facilities have prevented and stand to prevent billions of tons of emissions.
The Endangerment Finding is more fundamental than the regulations it supports; GHG regulations have gone through successive rulemakings during each of the Obama, first Trump, and Biden administrations seeking to augment or weaken them based on administration priorities. A repeal of the Endangerment Finding, by contrast, would hinder EPA’s ability to regulate GHGs for years to come.
EPA’s Proposed Arguments
EPA’s rollback proposal can be thought of in three broad strokes. First, EPA proposes that its regulatory authority extends only to pollutants “for which the air pollution itself, through local or regional exposure to humans and the environment, endangers public health or welfare,” not to emissions like GHGs that operate on a global scale. Therefore, per EPA’s reasoning, the Endangerment Finding should never have been made. Both the text of the Clean Air Act and rulings from the Supreme Court contradict EPA’s assertions.
Second, EPA proposes that, even if it is authorized to regulate GHG emissions, scientific and judicial developments since 2009 “cast significant doubt on the reliability of” the Endangerment Finding. Of course, the science supporting a determination that GHG-induced climate change is dangerous to human health and welfare has only become more certain since then.
Third and finally, even if the Endangerment Finding stands, the agency argues that regulating GHG emissions from new U.S. motor vehicles would be “futile” as compared to the global problem of climate change. This is difficult to justify given that the United States is the largest historical emitter of GHGs, and that motor vehicles account for over 22 percent of all annual U.S. emissions. Essentially, EPA seems to argue, if it can’t fix the entire problem of climate change, it shouldn’t have to try.
The Local Perspective Matters Now
Local governments and elected officials are well-positioned to challenge EPA’s erroneous arguments by providing firsthand accounts and evidence of the impacts of GHG-induced climate change. Local leaders may not be climate scientists, but they are experts in how GHGs have contributed to dangerous extreme weather events, negative health outcomes, and destruction of critical infrastructure in their communities. They also can attest to the adaptation and disaster response costs their cities incur. The sky-high costs and other catastrophic consequences cities are already experiencing belie EPA’s assertions that GHGs from motor vehicles are not worth regulating. They also demonstrate that impacts from GHG-caused climate change are very much felt at the local level, even if GHG pollution is global in scale.
Local testimony is crucial for building the administrative record in this rulemaking. Under the Administrative Procedure Act (APA), courts reviewing agency actions are largely limited to the record the agency compiles in its rulemaking. The APA requires EPA to consider all comments submitted (whether orally or in writing) in the Endangerment Finding rulemaking alongside other materials to reach a reasoned conclusion. If it fails to do so, plaintiffs can sue to challenge the final decision by pointing to relevant evidence, comments, or data that EPA ignored or only selectively considered.
To put it another way, if a local government or elected official doesn’t submit a comment to say what’s at stake in the Endangerment Finding rulemaking, challengers in court likely can’t use that information. Local governments have a wealth of data to share with EPA and with eventual challengers to EPA’s final rule: infrastructure damage that has been caused by storms or other extreme weather; incidences of health disparities or mortality due to air pollution or climate events; jobs and productivity losses due to extreme weather, and detail on the costs that have been or will be incurred to adapt and respond to the effects of GHG pollution.
Drafting a Comment Letter
Stakeholders – including local governments, elected officials, businesses, community groups, and residents – may upload written comment letters to the docket for the Endangerment Finding rulemaking on or before September 22, 2025. Comment letters should clearly state the rulemaking’s docket number, which is EPA-HQ-OAR-2025-0194-0093. While online submittal is recommended by the agency, mail-in options are also provided on the docket page. A template for local government comments developed by the Sabin Center is available here.
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The proposed repeal of the Endangerment Finding and associated vehicle GHG standards represents a profound threat to federal climate protections and to the ability of local governments to safeguard public health and welfare. Cities and communities already bear the brunt of climate-related harms – from extreme weather and infrastructure damage to health risks and economic costs – and they rely on robust federal regulation to prevent further harm.
Local leaders have an opportunity to participate in the public comment process. By submitting firsthand accounts, they can ensure that EPA understands the real-world impacts of GHG pollution in their communities, build a strong administrative record for future legal challenges, and publicly affirm their commitment to the protection of public health and welfare.
The stakes are high: the Endangerment Finding underpins every federal regulation limiting GHG emissions. Its repeal would not only roll back existing protections but would make it far more difficult for future administrations to act. For cities, residents, and local governments, participating in this rulemaking is essential to defending the climate, public health, and the well-being of communities nationwide.
Amy Turner is the Director of the Cities Climate Law Initiative at the Sabin Center for Climate Change Law at Columbia Law School.
Great Job Amy Turner & the Team @ Climate Law Blog Source link for sharing this story.
