The biggest human contribution to global warming is from the relentless atmospheric buildup of carbon dioxide, and the prime source of this gas is power plants, which provide twice as much CO2 as all the cars on the road.

President Obama can do for power plants what the administration has done for vehicles: require reductions in CO2. The EPA has proposed a Carbon Pollution Standard for Future Power Plants, which would restrict the emission of greenhouse gases, requiring coal plants, in particular, to be more efficient and cleaner. It's up to the president to move on this proposal and use his executive power to set limits on the amount of carbon pollution new power plants can emit. "There are no indications that the new Congress will be receptive to effective climate legislation," says Daniel Lashof of the Natural Resources Defense Council. "But [Obama] can do these things without waiting for Congress."