[Illustrations, footnotes and references available in PDF version]
Climate models have long suggested that the intensity and frequency of hurricanes or tropical cyclones (TCs) may be significantly increased in response to global warming, as noted by Free et al. (2004), who have written that “increases in hurricane intensity are expected to result from increases in sea surface temperature and decreases in tropopause-level temperature accompanying greenhouse warming,” citing in support of this statement the studies of Emanuel (1987), Henderson-Sellers et al. (1998) and Knutson et al. (1998). Before accepting this climate-model-based projection, however, it is important to see what the world of nature has to say about the issue.