Some researchers argue that in practical terms, the allure to live near the sea will do far more to boost society's risk from such storms over the next several decades than any effect global warming could have on the storms themselves.
Until he concluded this study, Emanuel says he was among that group. Now, he says, global warming's impact on the storms may play a bigger a role than previously believed in putting societies at risk, particularly in less-developed countries. Dr. Emanuel's research, published Sunday on the journal Nature's website, adds a fresh perspective to the discussion about the effects of global warming on tropical cyclones, says Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research in Boulder, Colo.
Early on, concerns about the future of these storms arose based on computer forecasts and basic theory. "Given the information we had at the time, the results were overhyped a bit," Dr. Trenberth acknowledges. He notes that the study doesn't have much comment on the effects of storm surges and torrential rainfall that accompany land-falling hurricanes - factors far more destructive than winds.
Still, Emanuel's approach "adds a new element," says Trenberth. It shows a strong real-world correlation between the oceans' current warming trend - which scientists have linked to the heating- trapping effect of industrial carbon dioxide and other "greenhouse gases" - and the increasing power of tropical cyclones.
Other researchers have noted that this is more likely a natural period of intense activity for Atlantic hurricanes. For example, William Gray, a specialist in tropical meteorology at Colorado State University who pioneered seasonal hurricane forecasts, notes that the region goes through swings in activity that can span decades. He and his colleagues have noted that the US and its southern neighbors have faced above-average hurricane seasons for the past decade and is likely to do so for some time to come.