This greenhouse effect forms a shield that allows the sun’s radiant heat energy into our atmosphere and moves excess heat concentrations out of our atmosphere.  When gas concentrations in this shield are increased, excess gases become trapped inside our atmosphere causing increased global temperatures.

Common greenhouse gases found in the Earth’s atmosphere include water vapor, carbon dioxide, methane, nitrous oxide, ozone and chlorofluorocarbons.

Congressional sources told The Associated Press that the EPA will announce its proposed finding Friday April 17th and begin a comment period before issuing a final ruling.  This is the first step toward regulating pollution linked to climate change.

The action was prompted by a Supreme Court ruling two years ago that said greenhouse gases are pollutants under the Clean Air Act and must be regulated if found to be a human health danger.