Expert Point of View: EPA Repeals 2009 GHG Endangerment Finding

EPA’s repeal of the 2009 Greenhouse Gas (GHG) Endangerment Finding is not unexpected, but it adds further complexity to an already unsettled federal regulatory landscape.

It is important to remember what the Endangerment Finding did, and did not, do. The 2009 determination concluded that six greenhouse gases “endanger public health and welfare” under Section 202(a) of the Clean Air Act. It did not impose emission limits itself. Rather, it provided the legal predicate for regulating GHG emissions from motor vehicles and, subsequently, stationary sources. The U.S. Supreme Court’s decision in Massachusetts v. EPA (2007) required EPA to determine whether GHGs qualify as air pollutants under the Clean Air Act, leading directly to the 2009 finding.

As a result, repeal of the Endangerment Finding does not automatically eliminate existing federal regulations. Current rules remain in effect unless and until they are separately revised or vacated through formal rulemaking and judicial review. However, repeal would invite legal challenges to the validity of existing GHG standards and likely trigger additional proposed rollbacks across multiple sectors.

At the same time, any repeal is virtually certain to face immediate litigation. Courts have repeatedly upheld EPA’s authority to regulate greenhouse gases under the Clean Air Act, including in American Electric Power v. Connecticut (2011) and Utility Air Regulatory Group v. EPA (2014). Given the extensive scientific record underpinning the original finding — including reliance on assessments from the Intergovernmental Panel on Climate Change (IPCC), the U.S. Global Change Research Program, and the National Academies — the legal and evidentiary bar for reversing the determination is substantial. This issue will take time to work its way through the courts, creating continued regulatory uncertainty.

Operators should not adjust compliance programs in response to proposed or anticipated changes. The broader regulatory and market landscape continues to move toward increased emissions transparency and accountability:

• State-level programs, including many regulating greenhouse gas emissions management and reporting as well as climate risk disclosure laws, are expanding.
• International regulatory frameworks such as the EU Methane Regulation (EUMR) and EU’s Carbon Border Adjustment Mechanism (CBAM) and global methane pledges are influencing supply chains.
• Investor and lender expectations remain anchored in emissions risk management and climate disclosure.

Meanwhile, the scientific basis for GHG regulation remains clear. The most recent IPCC assessment concluded that human influence on the climate system is “unequivocal,” and that limiting warming requires deep, rapid, and sustained reductions in greenhouse gas emissions. That underlying scientific consensus has not changed.

At the end of the day, organizations that remain committed to rigorous emissions monitoring, measurement, and mitigation will be best positioned — not only to navigate regulatory shifts, but to meet investor expectations, maintain operational resilience, and preserve their social license to operate. Regulatory cycles may shift, but market, stakeholder, and scientific drivers for sound emissions management continue to strengthen.

Reach out to Elizabeth McGurk at elmcgurk@montrose-env.com with direct questions about this repeal.