Climate scientists have long known that hurricanes form much more easily when the water is warm.
In the past, they’ve told me the threshold temperature for promoting more tropical cyclone growth is about 28 degrees Centigrade, which is about 82 degrees Fahrenheit.
(Image: The average tropical sea surface temperature (black) and an estimate of the sea surface temperature threshold for convection (blue) have risen in tandem over the past 30 years. Credit: IPRC/SOEST/UHM.)
But does that threshold temperature change with a warming climate? New research suggests it does, which seems like good news for Hawai’i.
Researchers Nat Johnson and Shang-Ping Xie at the University of Hawai`i at Manoa’s International Pacific Research Center write in the journal Nature Geoscience that the threshold seems to rise along with climate warming.
They compared tropical ocean thunderstorm frequency with tropical sea temperatures over a 30-year period. Their finding was that the two measures track each other closely, with the threshold rising along with sea surface temperature at about a tenth of a degree Centigrade per year.
“The correspondence between the two time series is rather remarkable… The convective threshold and average see surface temperatures are so closely linked because of their relation with temperatures in the atmosphere extending several miles above the surface,” Johnson said.
The scientists say their research seems to indicate that this trend will continue.
What that means for the Islands is that warming climate does not necessarily mean more hurricane-type storms for Hawai’i—at least not purely because the water is warmer. One of the fears about climate and hurricanes has been that if the threshold didn’t rise, it could mean the water would be above the threshold longer each hurricane season, and we would be at greater risk.
N.C. Johnson and S.-P. Xie, 2010: Changes in the sea surface temperature threshold for tropical convection. Nature Geoscience, doi:10.1038/ngeo1004.
©Jan TenBruggencate 2010
The scientists have been saying that one of the reasons they expect more intense rainfall in some areas from global warming is because warmer air holds more moisture. I wonder if that holds true for hurricanes.
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