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President Barack Obama's stirring words in Monday's inaugural address offered his most soaring pledge in years to make a major assault on climate change — but that leaves the crucial question: “How?”

Prospects seem bleak for getting a major climate bill through Congress: If anything, the atmosphere on Capitol Hill has grown even more toxic since Obama's proposal for a cap-and-trade system to throttle carbon emissions died without a whimper before the 2010 midterm elections. And unless the U.S. reins in its own carbon and persuades nations like China to go along, it's going to be difficult to bring pollution levels down as...