What year did the EPA declare greenhouse gases a threat to public health?

The U.S. Environmental Protection Agency (EPA) on Friday, April 17, 2009 formally declared carbon dioxide and other heat-trapping gases to be pollutants that threaten public health and welfare. This action by the EPA set in motion a process that would lead to the regulation of the gases for the first time in the United States.The EPA said the science supporting the proposed endangerment finding was “compelling and overwhelming.”

Although the finding had been expected, supporters and critics said its issuance was a significant moment in the debate on global warming. Some Republicans in the U.S. House of Representatives and industry spokesmen warned that regulation of carbon dioxide emissions would raise energy costs and kill jobs. Most Democrats and environmental advocates said the decision was long overdue and would bring long-term social and economic benefits.

Prior to this action, the U.S. had come under fierce international criticism for trailing other industrialized nations in regulating emissions of carbon dioxide and other pollutants tied to global warming. With this move and additional steps by Congress, the American government could point to progress on efforts to curb heat-trapping gases as nations started to write new international treaties on handling climate change.