Jubilant Republicans may imagine that the most significant harbinger for America’s future was the banging of a gavel on January 6, opening the 108th Congress. Finally, GOP partisans may conclude, they call the shots. But it may be that the Earth itself is in charge. In 2002, the second hottest year on record, scientists saw Arctic Ocean ice coverage shrink by more than at any time since satellite measurements were first made a quarter century ago. And, they say, continued melting could leave the Arctic nearly ice-free by summer 2050. Americans need to pay attention to the winds of change...