What global warming may do to future storms.

If the White House wants to move the debate about Hurricane Katrina beyond the "blame game," here's a constructive step that President Bush could take to protect people in the future: Tackle global warming. True, we don't know whether Katrina was linked to global warming. But there are indications that global warming will produce more Category 5 hurricanes. Hurricanes derive their power in part from warm water, and so forecasting models show future hurricanes becoming more severe as sea surface temperatures rise. Global warming also makes hurricanes more destructive by raising the sea level, which leads to more serious coastal flooding. (According to the EPA, a two-foot rise would swallow a chunk of the U.S. bigger than Massachusetts.) Now that we've seen what a Katrina can do--and Katrina was only Category 4 when it hit Louisiana it would be crazy for Bush to continue refusing to develop a national policy on greenhouse gases.--Nicholas D. Kristof [9/11/05]