U.S. President Donald Trump has overturned a critical pillar of American climate protection. On Thursday he rescinded the Environmental Protection Agency’s (EPA) authority to regulate climate‑polluting emissions.

In 2009 an EPA study listed six greenhouse gases as hazardous to public health and gave the agency the power to control releases from the oil and gas sector, power plants and motor vehicles. Trump’s action officially cancels those “endangerment findings”.

The move is likely to spark a protracted legal battle. Trump criticized the previous policy as “catastrophic” and also announced the repeal of vehicle‑emission rules that were similarly grounded in the endangerment findings. During the Biden administration the EPA had sought to tighten those standards to push the auto industry toward cleaner cars.