Hurricanes to Be Sapped, Not Strengthened, by Warming?

Sara Goudarzi
for National Geographic News
April 18, 2007

Climate change could lead to stronger wind shear, a weather pattern that weakens hurricanes, a new study says. Some previous, widely publicized studies have linked global warming to stronger hurricanes.

(See "Warming Oceans Are Fueling Stronger Hurricanes, Study Finds" [March 16, 2006] and "Global Warming Link to Hurricane Intensity Questioned" [July 28, 2006].)

Previous simulations had found that as global atmospheric temperatures rise, sea surface temperatures rise as well.

And because warm ocean waters fuel hurricanes, that temperature rise was predicted to increase hurricanes (interactive: how hurricanes form).

The models, however, also project that the difference in wind speed and direction—an effect known as wind shear—will also increase due to rising temperatures.

An increase in wind shear could counteract the effect of rising sea surface temperatures and actually inhibit hurricane formation.

A Hundred Years of Hurricanes

In the tropical Atlantic, near-surface winds generally blow from east to west while winds in the upper atmosphere blow from west to east.

If the difference in the wind speed and direction between the two layers ramps up, the resulting mechanism could put the brakes on storms by tearing them apart.

"The models project that that difference should get larger in a warming world," said Gabriel Vecchi, an oceanographer at the U.S. Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey.

Vecchi is the lead author of a paper detailing the new hurricane model published today in the journal Geophysical Research Letters.

"We're not arguing at all that hurricanes are going to disappear under global warming," Vecchi said.

Continued on Next Page >>


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