WASHINGTON (AP) — The Trump administration on Thursday revoked a scientific finding crucial for U.S. climate regulation, marking one of its most aggressive moves against existing environmental policies. The decision rescinds the 2009 endangerment finding, which outlined how greenhouse gases such as carbon dioxide pose threats to public health and welfare.

The endangerment finding has been vital for nearly all climate regulations under the Clean Air Act, affecting emissions standards for automobiles and power plants. Experts predict that this action will lead to significant legal challenges and could dismantle regulations designed to reduce pollution and combat climate change.

E.P.A. Administrator Lee Zeldin described the repeal as a historic deregulatory action. Environmental advocacy groups have condemned the move, labeling it the largest assault on federal climate policy in U.S. history.

"Withdrawing this finding is a radical and irresponsible step that compromises our ability to tackle climate change effectively and protect public health," said Gina McCarthy, a former EPA administrator.

The Supreme Court has previously recognized greenhouse gases as air pollutants, solidifying the endangerment finding as a legal basis for various climate protections. Critics of the current administration's actions worry that reversing this finding could invalidate ongoing and future efforts to limit greenhouse gas emissions from a wide range of sources, ultimately exacerbating climate change effects.

In coordination with this repeal, Zeldin announced a proposal to postpone restrictions on greenhouse gas emissions from vehicles, which the Trump administration argues will allow for greater consumer choice and lower prices. However, environmental groups fear this will prolong the use of high-polluting gasoline vehicles, threatening public health and the environment.

As the nation grapples with increasingly severe climate-related disasters, the implications of the administration's actions will be closely monitored by stakeholders advocating for sustainability and environmental stewardship.