Here's a story of two presidents, Barack Obama of the United States and Mohamed Nasheed of the Maldives.

Both are young and charismatic. Both were elected last fall to replace discredited incumbents (Nasheed's predecessor ruled the island nation for three decades and kept him in a political prison for years). Both have troublesome legislatures (the opposition party controls the chamber in the Maldives).

But on the biggest question the planet faces -- if we'll take action in time to slow down global warming -- they couldn't be more different. One, Nasheed, is leading the fight. The other, as we saw last weekend when he announced that there would be no new treaty anytime soon, is only half in the battle. They both may go to the U.N.-sponsored climate conference in...