The 112th Congress has just begun, and so have the attacks on the Environmental Protection Agency's ability to regulate greenhouse gases.

Three Republican House members -- Marsha Blackburn (Tenn.), Shelley Moore Capito (W. Va.) and Ted Poe (Tex.) have each introduced separate bills aimed at blocking EPA from regulating carbon dioxide and other greenhouse gases under the Clean Air Act.

The three measures hamstring the agency's authority in different ways: Blackburn's would "amend the Clean Air Act to provide that greenhouse gases are not subject to the Act, even though the Supreme Court ruled in 2007 that they are; Capito's would delay EPA from regulating carbon dioxide and methane for two years; and Poe's would prohibit any agency funding to be used to implement or enforce a cap-and-trade program for greenhouse gases.