September 11, 2005
The Storm Next Time

By NICHOLAS D. KRISTOF
New York Times (excerpts; emphasis added)

If the White House wants to move the debate about Hurricane Katrina beyond what it calls the "blame game" for bodies decomposing in the streets of New Orleans, then 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. Now that we've all seen what a Katrina can do - and Katrina was only Category 4 when it hit Louisiana - it would be crazy for President Bush to continue to refuse to develop a national policy on greenhouse gases.

Hurricanes derive their power in part from warm water, and so forecasting models show future hurricanes becoming more severe as sea surface temperatures rise. One summary of 1,200 simulations published in the Journal of Climate last year showed that rising levels of greenhouse gases could triple the number of Category 5 hurricanes.

Moreover, there's empirical evidence that hurricanes have already become more intense (but not more frequent). Nature magazine this summer reported a new study by Kerry Emanuel, a hurricane guru at M.I.T., indicating that by one measure hurricanes have almost doubled in intensity over the last 30 years.

That reflects natural cycles as well. But Professor Emanuel writes: "The large upswing in the last decade is unprecedented, and probably reflects the effect of global warming."

He adds: "My results suggest that future warming may lead to ... a substantial increase in hurricane-related losses in the 21st century."