Landsea is a reliable source on hurricane frequency. Chris has a short guest post at Prometheus on the new paper “Increased tropical Atlantic wind shear in model projections of global warming”. Chris writes:
My reading of the paper by Vecchi and Soden is that this is a very important contribution to the understanding of how global warming is affecting hurricane activity. The study thoroughly examines how the wind shear and other parameters that can alter the number and intensity of hurricanes because of manmade global warming. What they found - surprisingly - is that in the Atlantic that the wind shear should increase significantly over a large portion of where hurricanes occur - making it more difficult for hurricanes to form and grow. This was identified in all of the 18 global climate models they examined. (Perhaps it’s not that surprising given that Knutson/Tuleya 2004 showed some of the same signal for the more reliable models back then. Now the signal is in ALL of the CGCMs.) Even the MPI changes in the Atlantic appear mixed, due to the smaller SST increases there (with more uniform upper trop temp changes) compared with the rest of the global tropics/subtropics.
One implication to me is that this further provides evidence that the busy period we’ve seen in the Atlantic hurricanes since 1995 is due to natural cycles, rather than manmade causes. We’ve seen a big reduction in wind shear in the last thirteen hurricane seasons, which is OPPOSITE to the signal that Vecchi and Soden have linked to manmade global warming changes. Another implication is that this paper reconfirms earlier work that suggests that global warming will cause very small changes to Atlantic hurricanes, even several decades from now.
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