Why some environmentalists believe the president has the power to sidestep the Senate and commit the US to a global pact. In 1997, in the Japanese city of Kyoto, the Clinton administration agreed to a groundbreaking treaty to combat global warming. And that's when the trouble started. The Senate had unanimously refused to approve the Kyoto Protocol, and in the end the Clinton administration didn't even submit it for a vote in the upper chamber. This made the US both the world's biggest polluter and, ultimately, the only industrialized nation to reject the accord. Now, as world leaders attempt to...