The 31 actions are part of what Environmental Protection Agency Administrator Lee Zeldin called "the greatest and most consequential day of deregulation in US history," as he promised to "unleash American energy" and "revitalize the American auto industry."
Among the most significant of them is revisiting a 2024 rule that requires coal-fired plants to eliminate nearly all their carbon emissions or commit to shutting down altogether, a cornerstone of former Democratic president Joe Biden's climate agenda.
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Hailed by environmental groups as a "gamechanger," the regulations were set to take effect from 2032 and would have also required new, high capacity gas-fired plants to slash their carbon dioxide output by the same amount -- 90 percent -- achievable only through carbon capture technology.
The Biden administration estimated the rule would prevent 1.4 billion metric tons of carbon entering the atmosphere through the year 2047, equivalent to nearly one year of total greenhouse gas emissions from the power sector in 2022.
- 'Polluters are celebrating' -
"Corporate polluters are celebrating today because Trump's EPA just handed them a free pass to spew unlimited climate pollution, consequences be damned," said Charles Harper, of the nonprofit Evergreen Action.
President Trump has long dismissed climate change as a "scam" and his second administration has begun enacting sweeping staff cuts at the National Oceanic and Atmospheric Administration (NOAA), vital to the nation's climate research efforts.
The new deregulation package also targets stricter vehicle emissions standards set to come into force by 2027, which Trump has derided as an "electric vehicle mandate."
Another major move involves redefining what constitutes "waters of the United States" under the Clean Water Act.
Zeldin's EPA argues that the Biden administration had failed to align with a 2023 Supreme Court ruling, which held that only "relatively permanent, standing or continuously flowing bodies of water," such as streams, rivers, lakes, and oceans -- should be covered.
- Mass layoffs expected -
Environmental group Earthjustice warned that it excluded tens of millions of acres of wetlands, vital ecosystems that filter water and provide flood protection, as well as millions of miles of small streams that provide drinking water and help generate tourism.
The EPA is also set to eliminate the nation's environmental justice offices that address pollution in low-income and minority communities across the United States, including Louisiana's infamous "Cancer Alley," which accounts for around a quarter of US petrochemical production.
"President Trump wants us to help usher in a golden age in America that is for all Americans, regardless of race, gender, background," Zeldin told reporters.
But Matthew Tejada of the nonprofit Natural Resources Defense Council said "Trump's EPA is taking us back to a time of unfettered pollution across the nation, leaving every American exposed to toxic chemicals, dirty air and contaminated water."
Grants that EPA has moved to cancel were "helping rural Virginia coal communities prepare for extreme flooding, installing sewage systems on rural Alabama homes, and turning an abandoned, polluted site in Tampa, Florida into a campus for healthcare, job training, and a small business development," added Tejada, who led EPA's environmental justice office under Biden.
Zeldin's EPA budget is expected to be reduced by 65 percent and the agency is preparing for mass layoffs.
