Scientists see evidence that hurricanes and typhoons have intensified. Are new responses needed?
For years, hurricanes and typhoons have served as poster children for the hazards of global warming.
When simulated tropical storms churn inside the silicon universe of researchers' computers, such cyclones grow in power, and sometimes in number as well, as tropical temperatures increase. But when researchers have looked for global warming's fingerprints on real tropical cyclones, the evidence often has been inconclusive.
Now, one of the top researchers in the field reports that worldwide, these storms are nearly twice as powerful today as they were 30 years ago. Global warming has intensified the trend, exerting an influence stronger than he would have believed even a few months ago, he says.
"I'd been thinking of a very modest response" of tropical cyclones to climate change, "and what we're seeing is not so modest," says Kerry Emanuel, a professor of atmospheric science at the Massachusetts Institute of Technology in Cambridge, Mass.
The upshot: The 21st century could be a rough one for people who settle in hurricane or typhoon-prone areas.
As a result, more communities should be drawing on the experience of states such as Florida in devising building and zoning codes that can reduce damage and fatalities, analysts say. For people who insist on building on vulnerable barrier islands or along fragile coasts, insurance companies should be given a freer hand in deciding who they will cover and what they will charge for hurricane insurance, researchers and policy analysts say.
Dr. Emanuel's results are appearing at a time when residents along the US Gulf Coast and throughout the Caribbean are still recovering from what forecasters are calling the most active start to the hurricane season on record. Since June 1, six storms grew strong enough to merit names - from Arlene to Cindy to Franklin. Three became hurricanes. Two reached a potent category four out of five. According to forecasters at the National Hurricane Center in Miami, hurricane Dennis, which reached category four on July 7, ranks as the earliest Caribbean storm on record to reach that strength.