The Trump administration on Thursday formally repealed the Obama-era legal finding that declared climate change a threat to public health, while also eliminating federal climate rules for cars and trucks that were built on that determination.
The move marks a sweeping shift in federal environmental policy and represents a significant escalation in the administration’s effort to roll back regulations it argues have burdened the U.S. economy.
By rescinding the 2009 “endangerment finding,” the administration has removed the legal foundation underpinning many federal climate regulations. The finding had determined that greenhouse gases pose a danger to public health and welfare, triggering the Environmental Protection Agency’s authority under the Clean Air Act to regulate emissions from motor vehicles.
The Clean Air Act requires the EPA administrator to regulate emissions of any pollutant from vehicles that “in his judgment cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare.” In 2007, the Supreme Court ruled that greenhouse gases qualify as air pollutants under the law and must be regulated if found to threaten public health.
In 2009, the Obama administration concluded that planet-warming emissions do, in fact, pose such a threat. That determination cited expected increases in ambient ozone levels across broad areas of the country, heightened risks of serious adverse health effects, and the impact of rising temperatures on mortality and morbidity. It also referenced evidence that human-induced climate change could alter extreme weather events.
Thursday’s repeal undoes that finding entirely.
The first Trump administration previously weakened vehicle emissions standards but stopped short of repealing the endangerment finding itself. This latest action goes further, eliminating the federal requirement that automakers reduce climate-related emissions. As a result, car manufacturers will no longer face federal mandates tied to reducing greenhouse gas output.
President Trump campaigned on dismantling Biden-era regulations that were so stringent they were expected to significantly push the auto market toward electric vehicles and hybrids and away from traditional gas-powered cars.
White House press secretary Karoline Leavitt described the repeal as historic.
“This will be the largest deregulatory action in American history,” Leavitt said Tuesday in announcing the change. She added that the move would save drivers money on new vehicles.
“This is just one more way this administration is working to make life more affordable for everyday Americans,” she said.
Under the now-repealed standards, officials had estimated that up to 7.2 billion tons of carbon dioxide emissions could have been prevented through 2055 — roughly four times the emissions of the entire U.S. transportation sector in 2021. Transportation accounted for 28 percent of U.S. emissions in 2022, making it the nation’s largest source of planet-warming emissions.
The Biden-era vehicle rules were also projected to reduce other forms of pollution, including preventing up to 2,500 premature deaths in 2055 and lowering rates of heart attacks.
The repeal of the endangerment finding is part of a broader effort by the Trump administration to undo climate-related regulations. Last year, the administration also proposed eliminating all climate rules for power plants, which represent the nation’s second-largest source of emissions.
There remains a broad scientific consensus that human activity, particularly the burning of fossil fuels, contributes to global warming and extreme weather. Some scientists have warned that certain climate impacts could become irreversible if global temperatures rise enough to cross so-called tipping points, such as large-scale melting of ice sheets.
Nonetheless, the administration has consistently argued that sweeping environmental mandates risk hampering economic growth and driving up costs for American consumers. With Thursday’s action, it has taken one of its most consequential steps yet in reshaping federal climate policy.
