Warming to Reduce, Not Increase Hurricanes

Jan. 23, 2008 -- Global warming could reduce how many hurricanes hit the United States, according to a new federal study that clashes with other research.

The new study is the latest in a contentious scientific debate over how man-made global warming may affect the intensity and number of hurricanes.

In it, researchers link warming waters, especially in the Indian and Pacific oceans, to increased vertical wind shear in the Atlantic Ocean near the United States. Wind shear -- a change in wind speed or direction -- makes it hard for hurricanes to form, strengthen and stay alive.

So that means "global warming may decrease the likelihood of hurricanes making landfall in the United States," according to researchers at the National Oceanic and Atmospheric Administration's Miami Lab and the University of Miami.

With every degree Celsius that the oceans warm, the wind shear increases by up to 10 mph, weakening storm formation, said study author Chunzai Wang, a research oceanographer at NOAA. Winds forming over the Pacific and Indian oceans have global effects, much like El Nino does, he said.

Wang said he based his study on observations instead of computer models and records of landfall hurricanes through more than 100 years.

His study is to be published Wednesday in Geophysical Research Letters.