Study shows hurricane impact of warmer Atlantic

Reuters Wednesday January 30 2008

By Michael Kahn

LONDON, Jan 30 (Reuters) - British researchers say they have shown that a half-degree Celsius temperature rise in the Atlantic ocean can fuel a 40 percent increase in hurricanes.

The finding by the team from University College London is a contentious one in the debate over how climate change affects weather and, especially, storms.

"A 0.5 degree C increase in sea surface temperature is associated with a 40 percent increase in hurricane frequency and activity," the British researchers wrote in their report, published in the journal Nature on Wednesday.

The team showed ocean warming is directly linked to the frequency, strength and duration of hurricanes, said Adam Lea, the research scientist who co-led the study.

The study, which did not look at whether greenhouse gases linked to global warming played a role in increasing water temperature, will help scientists better predict how warmer oceans might affect hurricanes, he added in a telephone interview.

"It is important that future climate models are able to reproduce the relationship between sea surface temperature and hurricane activity," Lea said. "If you are trying to predict some of the impacts of global warming you need to have that kind of sensitivity."

Hurricanes feed on warm water, leading to conventional wisdom supported by some recent research that global warming could be revving up more powerful storms.

U.S researchers, however, last week challenged this view, saying global warming could reduce the number of hurricanes hitting the United States with warmer waters resulting in atmospheric instabilities that prevent storms from forming.

HURRICANE SEASONS

Atlantic storms play a pivotal role in the global energy, insurance and commodities markets, particularly since the devastating 2004 and 2005 hurricane seasons, which hammered U.S. oil and gas production in the Gulf of Mexico.

The British team looked at storms that formed in the tropical North Atlantic, Caribbean Sea and Gulf of Mexico -- a region that produced nearly 90 percent of the hurricanes that struck the United States between 1950 and 2005.

Lea and his colleague Mark Sanders at University College London built a statistical model based on local sea surface temperature and wind to replicate hurricane activity over the past 40 years.

This allowed them to remove the effects of wind to determine the sole impact of sea surface warming.
"We are just linking how much activity you get for a specific temperature rise," he said.

"The results ... indicate that local sea surface warming was responsible for 40 percent of the increase in hurricane activity relative to the 1950-2000 average between 1996 and 2005," the researchers' report said. (Reporting by Michael Kahn, Editing by Maggie Fox and Charles Dick)