The U.S. Environmental Protection Agency on Thursday revoked its 2009 “endangerment finding,” setting off a fresh fight over the scientific and legal basis for regulating planet-warming greenhouse-gas emissions. The finding concluded that carbon dioxide and other greenhouse gases—released by burning fossil fuels such as coal, oil and gas—endanger public health and welfare.
EPA’s action matters because the 2009 endangerment finding has been treated as a central trigger for downstream rules since it took effect in 2010, including during President Barack Obama’s first term. For more than a decade, it has supported new regulations targeting greenhouse-gas emissions from vehicles, oil and gas facilities, and large industrial sources, including power plants, and it also set the stage for future rules related to emissions from some aircraft.
The legal pathway for the 2009 finding traces back to a 2007 U.S. Supreme Court decision that greenhouse gases are air pollutants subject to regulation under the Clean Air Act. According to the EPA’s own finding, the scientific conclusion was not limited to a narrow policy assessment; it was framed as an air-pollution determination tied to public health and welfare, which became the foundation for regulatory steps that followed.
In contrast, the Trump administration has argued that the 2009 endangerment finding harms industry and the broader economy and that it represents an improper scientific conclusion drawn by earlier administrations. The agency’s revocation is also tied, in part, to the administration’s broader stance that climate-modeling efforts have overreached and that long-term disaster trends may not show much change, as well as that climate has little impact on the economy.
Environmental advocates and climate scientists said revocation would do more than alter specific rules for cars and trucks. They argued that climate change worsens extreme weather—such as floods, heat waves and drought—and that rising global temperatures translate into more frequent and severe hazards that endanger people and increase damage. They also warned that reversing the finding would weaken trust in U.S. institutions tasked with protecting the environment.
Experts said EPA’s revocation repeals greenhouse-gas emissions standards for cars and trucks, but could also open the door to a wider rollback affecting stationary sources such as power plants and oil and gas facilities. David Doniger, a climate expert at the Natural Resources Defense Council, said the action could also complicate future efforts because a later administration would likely have to restart the scientific and legal process to establish a new endangerment finding—a step that could take years and face legal challenges.
As the policy fight moves into the courts, environmental groups said they are prepared to challenge EPA’s revocation. They pointed to a history in which federal courts have repeatedly rejected legal challenges to the finding, including a 2023 decision by the U.S. Court of Appeals for the District of Columbia Circuit.