The Environmental Protection Agency’s effort to reverse a landmark finding that greenhouse gas emissions threaten public health could have profound implications for current and future climate regulations.

EPA Administrator Lee Zeldin on Sunday defended the Trump administration’s move to repeal the so-called endangerment finding and cast doubt that greenhouse gas emissions endangers human health.

A proposed EPA rule would rescind the 2009 Endangerment Finding that carbon dioxide and other greenhouse gases endanger public health and welfare, which is the underpinning of many climate regulations under the Clean Air Act for motor vehicles and power plants.