HURRICANE wars have resumed, with claims that global warming is behind the increased number of high-intensity hurricanes across the world.
Last September, days after Katrina devastated New Orleans, Peter Webster and Judith Curry of the Georgia Institute of Technology in Atlanta claimed that the number of intense hurricanes had almost doubled over the past 35 years. The increase was worldwide, they said, and it was caused by rising sea temperatures.
The study was criticised for ignoring other variables known to influence hurricane intensity, including high humidity, atmospheric circulation (the large-scale movement of air), and the strength of horizontal shear winds. William Gray of Colorado State University, who compiles annual hurricane forecasts for the North Atlantic, said the findings were 鈥渘ot physically plausible鈥�.
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To address such criticisms, the team asked statisticians at Georgia Tech to look at their original findings, comparing the role of sea temperatures with the competing factors. Led by Carlos Hoyos, they conclude that all four factors have been working to increase the strength of hurricanes (Science, DOI: 10.1126/science.1123560).
The three additional factors, they say, can explain why hurricanes form on particular days in particular places. But, confirming the original conclusion, they say that the contribution from sea surface temperature dominates in every ocean. Gray has yet to comment.
