The Obama administration’s efforts to regulate greenhouse gases were vindicated when the U.S. Court of Appeals for the D.C. Circuit upheld EPA’s endangerment findings that carbon dioxide emissions threaten human health. The court rejected arguments that the rules were based on an arbitrary interpretation of the Clean Air Act (CAA) and undermined claims by EPA critics that the agency is overstepping its legal authority by regulating greenhouse gas emissions.

The decision appears to leave little room for a Supreme Court review and it probably means opponents of the EPA rules will have to turn to Congress.

Sen. Inhofe (R-Okla.), the top Republican on the Environment and Public Works Committee and a skeptic of man-made climate change, said the decision serves as a warning about what will happen if Congress doesn’t legislate on greenhouse gases.