Mar 5 2011
Models suggest that there may be fewer, but more powerful, hurricanes as the world warms
There’s tremendous variation in hurricane activity over time and from place to place. Various studies published since 2005 indicate that the number and/or strength of hurricanes have increased in various regions, especially since the 1970s. However, it’s likely that some hurricanes at sea went unnoticed in the days before satellites and hurricane-hunter aircraft, and that complicates the assessment. There’s no doubt, though, that hurricane activity has stepped up since the mid-1990s in the North Atlantic, where ocean temperatures have risen through long-term warming and an apparent multidecadal cycle in Atlantic currents. The tropics are part of a global trend toward ocean warming that goes hand in hand with atmospheric warming, and warm oceans provide the energy to drive hurricanes. As for the future, computer models tend to point towards fewer hurricanes overall (for reasons that aren’t yet firmed up) but a general strengthening of winds and rainfall in the hurricanes that do form.
Trends aside, a catastrophic storm can strike in any year, and it’s impossible to tie any single hurricane or other weather event directly to global warming. Take Hurricane Katrina, which ravaged New Orleans in 2005. Several hurricanes of comparable strength have been observed across the Atlantic over the past century. And the horrific damage caused to the city was the result not only of Katrina’s strength but also the storm’s track, the weakness of levees and many other factors. That said, the waters of the Gulf of Mexico that fuelled Katrina were at near-record warmth at the time.
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