What you need to know
For nearly two decades, the Environmental Protection Agency (EPA) has regulated greenhouse gas emissions by treating carbon dioxide (CO2) as a pollutant. The current administration is working to change this policy. Our brief considers:
- How did the EPA get the authority to regulate CO2?
- How easy is it to reverse the EPA’s finding?
- What potential implications would there be if CO2 were not subject to regulation?
This brief extends Everything Policy’s coverage of issues relating to energy production and climate change. The government’s ability or inability to regulate CO2 has a significant impact on all of these issues. You can find the related briefs here.
How did CO2 become a pollutant?
The Clean Air Act, passed in 1970, authorizes the EPA to regulate air pollutants that endanger public health or welfare. Initially, this authority targeted issues such as smog and lead. However, in 2007, the Supreme Court ruled in Massachusetts v. EPA that greenhouse gases, including carbon dioxide (CO2), should be considered air pollutants.
That ruling compelled the EPA to issue an “endangerment finding” in 2009, which is a legally binding determination that CO2 contributes to climate change and thus harms public health and welfare. The finding became the basis for EPA regulations on emissions from coal- and gas-fired power plants, car and truck exhaust, methane from the oil and gas industry, and other sources. Since these regulations were implemented, total CO2 emissions in the U.S. have decreased; however, this change is due to many factors, some unrelated to the regulations.
In 2022, Congress reinforced the EPA finding by including language in the Inflation Reduction Act that labels greenhouse gases as pollutants under the Clean Air Act, making reversal even more difficult.
What change is the current administration proposing?
In August 2025, Environmental Protection Administration Administrator Zeldin released a proposal to rescind the finding on CO2. The EPA argued that past agency personnel had overstepped their authority by issuing a broad determination that greenhouse gases endanger public welfare. Rather than revisiting the science, the proposal framed the endangerment finding as an unlawful expansion of EPA’s power under the Clean Air Act.
If finalized, the proposal would eliminate federal greenhouse gas standards for light, medium, and heavy-duty vehicles, repeal rules to limit power plant emissions, and withdraw carbon capture requirements.
Can the EPA reverse its CO2 endangerment finding?
In the past, courts have been clear that the EPA cannot unilaterally eliminate regulations once it has determined that a pollutant poses a threat to public health. The agency would need to conduct a new scientific review, publish a proposed rule in the Federal Register, undergo notice-and-comment, and issue a final rule. Declaring CO2 “not a pollutant” without such further scientific review and analysis would likely not withstand judicial scrutiny, although there has been no ruling on the current proposal.
The Takeaway
If the CO2 endangerment finding were rescinded, vehicle emissions standards tied to CO2 would be repealed, leaving only state-level restrictions in place. Power plant rules on carbon pollution would be eliminated, and Clean Air Act permitting requirements would be rendered invalid.
Other climate-related policies would remain, such as tax credits for renewable energy and Department of Energy efficiency standards; however, the federal regulatory backbone for reducing greenhouse gas emissions would be significantly reduced.
Policies regarding CO2 and other factors that affect climate are complex, are likely to have a longer-term impact on society, and intersect with other policy areas such as the cost of living, our national debt, sourcing of natural resources, and supply chain considerations, among others.
Enjoying this content? Support our mission through financial support.
Further reading
U.S. Environmental Protection Agency. (2009). Endangerment and cause or contribute findings for greenhouse gases under the Clean Air Act: Technical support document. https://tinyurl.com/y3bszmph (Accessed 8/20/2025)
White House. (2025). Unleashing American Energy - Executive Order. https://tinyurl.com/3n2a99ht (Accessed 8/20/2025)
Sources
Supreme Court of the United States. (2007). Massachusetts v. Environmental Protection Agency, 549 U.S. 497. https://tinyurl.com/5n7eey88 (Accessed 8/20/2025)
U.S. Environmental Protection Agency. (2025). What they are saying: Leaders praise EPA for launching the largest deregulatory action in U.S. history. https://tinyurl.com/rut8bhk7 (Accessed 8/20/2025)
U.S. Environmental Protection Agency. (2024). Greenhouse gas reporting program: Power plants. https://tinyurl.com/ykm23zcx (Accessed 8/20/2025)
U.S. Environmental Protection Agency. (2024). Fast facts on transportation greenhouse gas emissions. https://tinyurl.com/48rwn87w (Accessed 8/20/2025)
U.S. Congress. (2022). Inflation Reduction Act of 2022, H.R. 5376, 117th Congress. https://tinyurl.com/yu4md5um (Accessed 8/20/2025)
Congressional Research Service. (2022). The endangerment finding and the Clean Air Act: Legal background (CRS Report No. R48168). Library of Congress. https://tinyurl.com/56yse3bk (Accessed 8/20/2025)
Politico News. (2025). House releases Interior-EPA spending bill with deep cuts. https://tinyurl.com/2ddjvsw8 (Accessed 8/20/2025)
Politico Pro. (2025). Trump dismisses scientists writing the National Climate Assessment. https://tinyurl.com/32nxvew9 (Accessed 8/20/2025)
Natural Resources Defense Council. (2017). The EPA endangerment finding: Setting the foundation for climate action. https://tinyurl.com/335wtvfd (Accessed 8/20/2025)
Contributors
Lindsey Cormack (Content Lead) is an Associate Professor of Political Science at Stevens Institute of Technology and the Director of the Diplomacy Lab. She received her PhD from New York University. Her research explores congressional communication, civic education, and electoral systems. Lindsey is the creator of DCInbox, a comprehensive digital archive of Congress-to-constituent e-newsletters, and the author of How to Raise a Citizen (And Why It’s Up to You to Do It) and Congress and U.S. Veterans: From the GI Bill to the VA Crisis. Her work has been featured in The New York Times, The Washington Post, Bloomberg Businessweek, Big Think, and more. With a drive for connecting academic insights to real-world challenges, she collaborates with schools, communities, and parent groups to enhance civic participation and understanding.
William Bianco (Research Director) is Professor of Political Science at Indiana University and Founding Director of the Indiana Political Analytics Workshop. He received his PhD from the University of Rochester. His teaching focuses on first-year students and the Introduction to American Government class, emphasizing quantitative literacy. He is the co-author of American Politics Today, an introductory textbook published by W. W. Norton, now in its 8th edition, and authored a second textbook, American Politics: Strategy and Choice. His research program is on American politics, including Trust: Representatives and Constituents, and numerous articles. He was also the PI or Co-PI for seven National Science Foundation grants and a current grant from the Russell Sage Foundation on the sources of inequalities in federal COVID assistance programs. His op-eds have been published in The Washington Post, Indianapolis Star, Newsday, and other venues.
