Warmer Atlantic Explains Worse Hurricanes

Jan. 30, 2008 -- When the water in the hurricane breeding grounds of the Atlantic warms one degree in the dead of summer, overall hurricane activity jumps by half, according to a new study.

Scientists have long known that hurricanes get their enormous energy from warm waters, so the warmer the water, the more fuel a storm has to either start up or get stronger. The study calculates how much storm frequency and strength is due to warmer sea water, said author Mark Saunders, professor of climate prediction at the University College London.

Saunders found a distinct numerical connection between the ups and downs of water temperatures and how nasty hurricane season gets. That helps explain why hurricanes have been so much worse in the past dozen years, and even why 2007 -- with waters slightly cooler than normal -- was an exception and not that bad a hurricane year, Saunders said.

"It's very surprisingly sensitive to small changes in sea surface temperature," he said.

His study, published Thursday in the journal Nature, found that changes in wind patterns caused a bigger shift in hurricane activity, but he concentrated his analysis on what sea temperature did to storms. Saunders didn't look at what caused the temperature fluctuations, although he believes that climate change is a contributing factor.

Scientists have clashed in recent years about whether man-made global warming has already increased hurricane activity in the Atlantic by warming the sea and shifting wind patterns, and what global warming may mean in the future.

Saunders focused on the water temperature in a band of tropical sea that stretches from around Puerto Rico and the northern coast of South America east to near the coast of Africa since 1950. He looked at hurricane activity since 1965.