Are the stars finally aligned for a global climate change treaty? After years of frustration, momentum seemed to change in an instant last Monday. President Obama’s second inaugural address made it clear he was going to lead the world on the issue, his words a “clarion call to action” as one observer put it. Obama’s first term was marked by one failure after another on the climate issue. For instance, his efforts to craft an agreement at Copenhagen in December 2009 were frustrated by developing nations, and subsequent conferences, such as the one last November and December in Doha, have...