Tropical cyclone activity has long been understood to respond to changing properties of the large-scale atmospheric and oceanic environment. In this essay, evidence for changing tropical cyclone activity is reviewed, and the controversy surrounding the quality of the data itself and the attribution of these environmental changes to various natural and anthropogenic causes, is discussed. At the same time, there is growing evidence that global tropical cyclone activity may itself affect climate in such a way as to mitigate tropical climate change but amplify climate change at higher latitudes. This evidence is reviewed, and possible routes forward in exploring these effects are suggested.

© 2008 American Meteorological Society