EPA Puts "Holy Grail" of Climate Change in Crosshairs by Reconsidering Endangerment Finding and Other Regulations

On March 12, 2025, the EPA announced numerous actions aimed at reconsidering regulations, with a special focus on climate change regulations. While EPA targeted some climate change rules individually, the announced reconsideration of the Endangerment Finding and the SCC may compromise the legal underpinnings of all GHG regulation.

EPA's Administrator Lee Zeldin took particular aim at the 2009 Endangerment Finding, saying, "I've been told the Endangerment Finding is considered the Holy Grail of the climate change religion." The Endangerment Finding stems from the Supreme Court's holding in Massachusetts v. EPA. The Court concluded that GHGs fall under the Clean Air Act's definition of "air pollutant," and that EPA "offered no reasoned explanation for its refusal to decide whether [GHGs] cause or contribute to climate change." The Court noted that the Clean Air Act requires regulation of air pollutants that in EPA's "judgment cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare." In 2009, EPA found that GHG emissions do endanger public health and welfare. This finding, called the Endangerment Finding, allows EPA to regulate GHGs.

Along with the 2009 Endangerment Finding, EPA is targeting the calculation of the SCC. The SCC is how EPA calculates the cost each emitted ton of carbon dioxide equivalent (CO2e) would have on society. The current SCC calculation was released as a technical report in November 2023 for the Oil and Gas Methane Rule. This SCC calculation included a cost prediction extending to the year 2300, instead of the previous 2100 prediction. The calculation received criticism for being too speculative because of its attempt to predict 300 years of economic growth, innovation, and population. 

Both of these reconsiderations could threaten all GHG regulation. If EPA reconsiders the 2009 Endangerment Finding and finds that GHGs do not present the requisite endangerment, then EPA would lose the power to regulate GHGs under the Clean Air Act. Likewise, EPA uses the SCC to justify expenses of regulation. Under E.O. 12866, agencies, like EPA, must assess both the costs and benefits of each regulation and only propose or adopt regulation "upon a reasoned determination that the benefits of the intended regulation justify its costs." EPA used the revised SCC to account for the cost of emitting GHGs under its 2024 Clean Power Plan 2.0 rule. If EPA concludes that the revised SCC is too uncertain, the Clean Power Plan 2.0 rule and other rules that used the revised SCC may be susceptible to challenges on cost effectiveness grounds. (And EPA has already separately stated that it will reconsider the 2024 Clean Power Plan 2.0 rule regardless of the SCC.)

A reconsidered SCC may also have ramifications for project authorization reviews under the National Environmental Policy Act ("NEPA"). The SCC is used frequently to assess the environmental effects of new projects in Environmental Impact Statements ("EISs") and Environmental Assessments ("EAs"). A lower SCC could facilitate more development of energy projects that trigger NEPA.

EPA may face some hurdles in revising the Endangerment Finding and the SCC. First, it would have to create a scientific record that supports removing the 2009 Endangerment Finding and lowering or eliminating the SCC, which could take time. Next, the changes would need to withstand judicial review, where EPA's interpretation may be subject to less deference under Loper Bright, but even that is unclear given it would relate to scientific and technical findings that may still be entitled to some deference. Although EPA claimed in its press release that it is not "pre-judging" its ultimate conclusion on the endangerment finding, EPA strongly foreshadowed the outcome of the reconsideration by announcing in a related press release that EPA was "driving a dagger through the heart of climate-change religion and ushering in America's golden age." 

The timing and specific outcomes of EPA's review of these rules is uncertain at this point and, as mentioned, EPA may face challenges to the repeal or revision of the existing regulations. In addition, state and local regulation of greenhouse gases will likely not be impacted by reconsideration of federal regulations and therefore will remain applicable. Affected industries should monitor developments to identify applicable requirements moving forward.