Are more Katrinas in our future?

Scientific differences over the effect of global warming on hurricanes in the North Atlantic are being resolved, but the news is not so good. While a warming climate is likely to produce fewer hurricanes, more researchers agree now that the storms that do reach hurricane strength more often will be the kind that wrecked New Orleans in 2005. 

In fact, new modeling work by U.S. government researchers sees a doubling in the frequency of the most intense and destructive Category 4 and Category 5 hurricanes by the end of the century.  Other studies show that the top 24 percent of hurricanes making landfall in the U.S. account for 86 percent of all the
damage.

These images provided courtesy of the geophysical lab compare the most intense hurricanes in the current climate to the number of such storms at the end of the century.  Only the high-intensity category 4-5 storms are shown.

Published in the journal Science, the new study by researchers at NOAA's Geophysical Fluid Dynamics Laboratory in Princeton, NJ appears to bridge the apparently conflicting results between coarse climate models that don't see hurricanes clearly and hurricane forecasting models that don't simulate global warming.

The group took the average ocean and atmospheric conditions from an ensemble of global climate models, transferred them to a more highly resolved regional model of the North Atlantic, which saw hurricanes form, and then to a higher-resolution hurricane forecast model that simulated their intensity.

This kind of "downscaling," as modelers call it, is a clever way to work around a problem of inadequate computing power, but the authors of the study know that it is not really a substitute for a single super-power model that integrates all of the physics of climate and hurricanes.  As co-author Morris Bender suggests in a Science podcast interview, such a model is "perhaps three to five years down the road."