US President Donald Trump revoked a 2009 scientific finding that declared greenhouse gases a threat to public health. The rule had formed the legal foundation for federal efforts to limit emissions from cars, power plants, and industry.
The White House called the move the “largest deregulation in American history,” claiming it will lower vehicle costs by $2,400 and ease burdens on automakers. Environmental groups warned it is the most significant climate rollback to date and vowed to challenge it in court.
Trump attacks Obama-era climate policies
Speaking in the Oval Office, Trump called the 2009 finding “a disastrous policy that damaged the American auto industry and raised consumer costs.” He described Democrats’ climate agenda as a “radical scam” based on the regulation.
Former President Barack Obama said repealing the rule leaves Americans less safe and less healthy. He argued the change mainly benefits the fossil fuel industry at public expense.
How the endangerment finding shaped US climate law
The Environmental Protection Agency first assessed greenhouse gases in 2009, declaring six major gases, including carbon dioxide and methane, dangerous to human health. With Congress unable to pass climate legislation, the finding became central to federal efforts to reduce emissions.
Meghan Greenfield, former EPA attorney, explained that the rule governs emissions from vehicles, power plants, oil and gas production, landfills, and aircraft. “All standards across sectors rely on this single determination,” she said.
Trump officials argued the rollback could save over $1 trillion and reduce energy and transport costs. They claimed automakers will save $2,400 per vehicle. Diana Furchtgott-Roth, formerly with the Department of Transportation, said the regulations had pushed manufacturing overseas to dirtier production sites.
Environmental advocates disputed the claims. Peter Zalzal from the Environmental Defense Fund warned Americans could face $1.4 trillion in extra fuel costs, 58,000 additional premature deaths, and 37 million more asthma attacks.
Effects on the auto industry
Automakers face uncertainty because producing less fuel-efficient cars could limit international sales. Climate law expert Michael Gerrard said the rollback enforces relaxed fuel economy standards but may reduce global demand for US vehicles.
Observers noted unintended consequences. The 2009 finding allowed federal authorities to block stricter state laws and climate-related nuisance lawsuits. Greenfield said the rule had prevented many cases and predicted new legal challenges from states and nonprofits.
Scientific debate
The Department of Energy formed a panel last year questioning widely accepted science on greenhouse gas warming. That report guided the proposal to overturn the 2009 finding. Many experts criticized the panel as biased and unrepresentative.
A federal judge ruled the department violated the law in forming the panel. Legal analysts said the administration may seek a Supreme Court review. If successful, the repeal could become permanent, preventing future presidents from reinstating the rule without Congress.
Greenfield said, “The EPA is leaving this space entirely. A Supreme Court ruling would block any future president from reversing this decision.”

