On Tuesday, as 170 million people from Dallas to Boston suffered under heat alerts, the Environmental Protection Agency released its long-promised proposal to revoke , once and for all, a scientific finding it has used to fight climate change. More specifically, the plan is to rescind the 2009 “endangerment finding” that undergirds that agency’s ability to regulate planet-heating greenhouse gas emissions, and eliminate all remaining limits on tailpipe emissions from motor vehicles and engines.