Fewer Atlantic hurricanes in a warmer climate?
A new regional modeling framework has been used to downscale GCM projections for an analysis on potential connections between global warming and hurricane formation in the North Atlantic. Downscaling techniques, such as this, are necessary since the resolution of GCMs is too coarse to realistically model small-scale features such as tropical cyclones. The authors were able to reproduce the observed rise in Atlantic hurricanes over the past 25 years, although the simulated hurricanes are not as intense as those observed. In a warmer future, the model generates substantially fewer tropical storms (-27%) and hurricanes (-18%). This is apparently due to higher levels of wind shear and other changes in cyclone development processes. These model results suggest that the observed rise in Atlantic hurricanes may not be due to absolute increases in sea surface temperature in the Atlantic, but rather due to the warming of the tropical Atlantic relative to other tropical basins. They also showed a very small increase in the intensity of storms, and increased rainfall associated with storms.
Source: Knutson, T.R., J.J. Sirutis, S.T. Garner, G.A. Vecchi & I.M. Held. 2008. Simulated reduction in Atlantic hurricane frequency under twenty-first century warming conditions. Nature Geoscience 18 May 2008; doi:10.1038/ngeo202.