Climate Change and Hurricane Intensity

Among the more serious consequences of climate change are possible changes in the frequency, intensity and location of severe weather events. Among these, tropical cyclones rank as the most destructive, with single events in recent decades taking hundreds of thousands of lives and costing tens of billions of U.S dollars. It is therefore of considerable importance to understand how climate change, whether from natural or anthropogenic causes, might affect hurricane activity.

Unfortunately, accurate measurements of tropical cyclone intensity have not made long enough to make it feasible to detect long term trends in global hurricane intensity. On the other hand, recent work on the record of storms over the last few decades has revealed that the cumulative frequency distribution of hurricane intensity, normalized by potential intensity, appears to be a universal function, independent of basin and season. This universal function is such that the probability of any single event reaching any given intensity is uniform up to the potential intensity, and zero above that intensity. The universality of this distribution function means that the statistics of hurricane activity may be described in terms of only two parameters: the overall frequency of events, and the potential intensity. While we cannot yet address the issue of overall frequency, I will present analyses that appear to show that global potential intensity has been increasing in the last few decades, implying that the average and peak intensity of storms should be increasing.