CNN.com, May 24, 2007
(Reuters) -- Hurricanes over the past 5,000 years appear to have been controlled more by El Nino and an African monsoon than warm sea surface temperatures, such as those caused by global warming, researchers said Wednesday.
The study, published in the journal Nature, adds to the debate on whether seas warmed by greenhouse gas emissions lead to more hurricanes, such as those that bashed the
Some researchers say warmer seas appear to have contributed to more intense hurricanes, while others disagree. The U.N. International Panel on Climate Change said this year it was more likely than not that humans contribute to a trend of increasingly intense hurricanes.
Frequent strong hurricanes thrived in the Western Atlantic during times of weak El Ninos, or warming of surface waters of the
"Tropical sea surface temperatures as warm as at present are apparently not a requisite condition for increased intense hurricane activity," Jeffrey Donnelly, the lead author and researcher at the Woods Hole Oceanographic Institution, said in the study.
Intense hurricanes made landfall during the latter half of the Little Ice Age, a period of cooling that occurred approximately from the 14th to mid-19th centuries, he said.
Donnelly took core sediment samples from coastal lagoons in Puerto Rico to determine the frequency and strength of hurricanes that hit the
He compared the deposits with historic paleoclimatology records to determine that the storms hit during periods when El Ninos were weak and when Western African monsoons were strong.
Intense hurricanes hit when local sea surface temperatures were warm or cool. In fact, "the
Changes in intense hurricane activity should be better predicted with more study of the Eastern Pacific and West African climate patterns, it said.
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