Barack Obama may believe a lot of things, but he probably doesn't believe the Sierra Club is key to his re-election. His decision to nix the Keystone XL pipeline will cost him votes but he did it anyway.

We'll admit that Mr. Obama's global warming talk has often seemed to us perfunctory. Perhaps we mistook his lack of heat for a lack of conviction. He just released his first 2012 campaign ad and it's a paean to green energy. Maybe he's no less a believer than Al Gore, for all the problems this might seem to pose for what...