So, EPA is ruling that carbon dioxide and other GHC’s are a problem.  As noted here by the AP

Under a Supreme Court ruling, the so-called endangerment finding is needed before the EPA can regulate carbon dioxide and five other greenhouse gases released from automobiles, power plants, and factories under the federal Clean Air Act.

This of course does not tell the whole story.  That ruling by the Supreme Court was hard fought, and, as reported here by the NY Times, it was

a strong rebuke to the Bush administration, which has maintained that it does not have the right to regulate carbon dioxide and other greenhouse gases under the Clean Air Act, and that even if it did, it would not use the authority.