If approved, the EPA’s proposal would rescind the 2009 decision that set forth a legal basis to regulate greenhouse gases as pollutants. Known as the "endangerment finding," it allowed the EPA to limit emissions from vehicles, power plants, and oil and gas companies under the Clean Air Act.

If successful, the repeal could strip away the federal government’s most powerful way to control the country’s planet-warming pollution and fight climate change.

The endangerment finding underpins the EPA's ability to regulate greenhouse gases. The Trump administration is trying to reverse it.