President Donald Trump’s administration on Tuesday proposed revoking a scientific finding that has long been the central basis for U.S. action to regulate greenhouse gas emissions and fight climate change.

The proposed Environmental Protection Agency rule would rescind a 2009 declaration that carbon dioxide and other greenhouse gases endanger public health and welfare. This “endangerment finding” is the legal underpinning of many climate regulations under the Clean Air Act for motor vehicles, power plants and other pollution sources that are heating the planet.