Climate Variations and Hurricane Activity: Some Theoretical Issues

Abstract

This chapter reviews the present state of knowledge concerning the dependence of hurricane activity on climate. This state of knowledge relies on theory, observations, and numerical models. Theory suggest that an upper bound on the intensity of hurricanes, as measured by their maximum wind speeds, would increase with global warming, with the amount of increase strongly dependent on the degree of warming of tropical oceans, of which estimates by climate models must be treated with skepticism at present. While the upper bound on intensity would increase, little is known about how the average intensity of storms might change. Storm frequency is another matter and is very sensitive to many features of the general circulation of the tropical atmosphere. Climate model simulations produce very different responses of hurricane frequency to climate change and should not be considered reliable at present, though in principle it should be possible to use such models to predict general levels of storm activity. There is no evidence whatsoever that the regions susceptible to hurricanes would undergo any net expansion or contraction. The progress in understanding the relationship between hurricane activity and climate is impeded by the lack of resources and talent directed toward this problem.