Five years is a lifetime when it comes to the politics of climate change. Five years after the House voted on the cap-and-trade bill offered by Rep. Henry Waxman (D-Calif.) and then-Rep. Ed Markey (D-Mass.), the economy is in much better shape. Public support for action appears stronger. A boom in domestic production has already accelerated the switch from coal to natural gas. But the idea of putting the federal government in charge of slashing emissions across a big, complex economy is still contentious.