For seven long years, President Bush has refused to confront the challenge of climate change and provide the leadership that this country and the world needs to reduce greenhouse gases and avoid the destructive consequences of global warming. The Senate, and all three presidential candidates, have a chance to provide that leadership. Next week, the Senate is scheduled to take up a bill sponsored by John Warner, the Virginia Republican, and Joseph Lieberman, the Connecticut independent, that seeks aggressively to reduce emissions from all sectors of the economy. Bush, predictably, opposes the bill. Add that to the slim Democratic majority and the complexity of the bill itself, and the chances of getting 60 filibuster-proof votes are modest at best.

The scientific case for action, strong five years ago, is even more persuasive now. Authoritative assessments from the Intergovernmental Panel on Climate Change, among other studies, have left little doubtthat the world is heating up, that man-made emissions are largely responsible and that swift action is necessary to avoid widespread environmental damage. Bush can no longer plausibly deny the science. What he resists is the need for a full-throated response. The Senate can usher in a new era of American leadership when it convenes next week.