International Herald Tribune: As world leaders gather in Washington, they would do well to remember that we face two crises. The global financial crisis is most immediate; the more existential is climate change. The urgency of the first is no excuse for neglecting the second. To the contrary, it is an opportunity to kill two birds with one stone. Put aside the familiar arguments: that the science on climate change is clear, that every day we do not act the problem grows worse, that fighting global warming is a …