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 announced on Tuesday a proposal to withdraw the 2009 Endangerment Finding, which concluded that six greenhouse gases, including carbon dioxide and methane, pose a threat to public health and welfare. The finding was supported by a 2007 Supreme Court ruling in Massachusetts v. EPA, affirming that greenhouse gases are pollutants under the Clean Air Act.