EPA has submitted to the White House a finding that carbon dioxide is a danger to public health and a proposed rule to regulate it under the Clean Air Act. See more here.
If there is going to be policy and regulation of GHG’s, Congress should address it with legislation, not allow the EPA to proceed with this rulemaking, because Congress is able to consider the bigger picture and tradeoffs in a way EPA and the Clean Air Act cannot. Perhaps the most important of those is considering how any US policy fits into the global picture–unilateral cuts by the US ensure a big hit to the economy and little reduction in globabl GHGs. And the international community is still far from a functioning agreement.
That said, Congress action on climate change is in itself is a scary path, since most proposed laws on GHGs coming out of Congress have been problematic. Shikha Dalmia wrote here about how the Senate cap and trade plan offers high costs and few benefits.
The Clean Air Act can be effiective, but is also a very constrained tool, and implementation of it has been problematic and wasteful. It tends to focus all resources on creating rules that will in theory limit harmful emissions, but has no mechanism for evaluating benefit-cost ratios, and even worse, none for analyzing measure already in place to see if they are more or less effective than predicted.
Ben Lieberman at Heritage has a similar critique.