The media typically hyperventilate when a tropical cyclone, or hurricane, passes through a populated region. If there is damage to be found, they find it; and almost unfailingly, there are warnings that tropical and coastal regions are doomed to suffer even worse buffetings in the future, as professionally-trained voices solemnly proclaim that hurricane-related destruction may well be increasing as a result of CO2-induced global warming.
Such reporting gives the public the distinct impression that CO2-induced global warming is an established fact, when this is definitely not the case (see our Editorial There Has Been No Global Warming for the Past 70 Years). It also suggests that hurricane frequency and intensity truly are increasing as a result of increasing air temperatures. The materials reviewed in this section of our website, however, tell a very different story.
In a major analysis of Atlantic basin hurricane characteristics, Landsea et al. (1999) reported on variations in tropical cyclone activity in this region over the period 1944-1996. They found decreasing trends for (1) the total number of hurricanes (click here for data), (2) the number of intense hurricanes (click here for data), (3) the annual number of hurricane days (click here for data), (4) the maximum attained wind speed of all hurricanes averaged over the course of a year, and (5) the highest wind speed associated with the strongest hurricane recorded in each year. 
In addition, they reported that the total number of Atlantic hurricanes making landfall in the United States decreased over the extended 1899-1996 time period (which fact has been subsequently reaffirmed by Easterling et al., 2000), and that normalized trends in hurricane damage in the United States between 1925 and 1996 reveal this parameter to have decreased at a rate of 728 million dollars per decade.
Moving further back in time in the Atlantic basin, Elsner et al. (2000) present data on major hurricane occurrences in Bermuda, Jamaica and Puerto Rico since 1700. Their data reveal that hurricanes at these locations occurred at far lower frequencies in the last half of the 20th century than they did in the preceding 250-year period. Between 1701 and 1850, for example, major hurricane frequency was 2.77 times greater than it was from 1951 to 1998, while from 1851 to 1950 it was 2.15 times greater. As for hurricane trends outside the Atlantic basin, one recent review of the subject reported "no discernible global trends in tropical cyclone number, intensity, or location" (Henderson-Sellers et al., 1998).
There can, however, be significant year-to-year fluctuations in the number of observed hurricanes, possibly as a result of factors related to the El Niņo-Southern Oscillation (ENSO) cycle (Walsh and Pittock, 1998). Wilson (1999), for example, examined Atlantic basin hurricane frequency over the period 1950 to 1998, finding that the probability of having three or more intense hurricanes during a warmer El Niņo year was approximately 14%, while during a cooler non-El Niņo year this figure jumped to 53%. In a separate study of Atlantic basin hurricanes over the period 1925 to 1997, Pielke and Landsea (1999) reported that average hurricane wind speeds during warmer El Niņo years were about 6 meters per second lower than during cooler La Niņa years. In addition, they reported that hurricane damage during cooler La Niņa years was twice as great as during warmer El Niņo years (1.6 billion dollars per year for La Niņa conditions as opposed to 800 million dollars per year for El Niņo conditions). These year-to-year variations thus indicate that, if anything, hurricane frequency and intensity tend to decrease under warmer conditions, which is just the opposite of the impression that is typically conveyed to the public.
In light of the results contained within these studies, it is clear that talk of more and stronger hurricanes in a warmer world is little more than "hot air." It has no basis in real-world observations, or even climate model predictions. To claim otherwise is to be either ignorant or disingenuous.
References
Bates, N.R., Knap, A.H. and Michaels, A.F. 1998. Contribution of hurricanes to local and global estimates of air-sea exchange of CO2. Nature 395: 58-61.
Cerveny, R.S. and Balling, R.C., Jr. 1998. Weekly cycles of air pollutants, precipitation and tropical cyclones in the coastal NW Atlantic region. Nature 394: 561-563.
Easterling, D.R., Evans, J.L., Groisman, P. Ya., Karl, T.R., Kunkel, K.E., and Ambenje, P. 2000. Observed variability and trends in extreme climate events: A brief review. Bulletin of the American Meteorological Society 81: 417-425.
Elsner, J.B., Liu, K.-B. and Kocher, B. 2000. Spatial variations in major U.S. hurricane activity: Statistics and a physical mechanism. Journal of Climate 13: 2293-2305.
Henderson-Sellers, A., Zhang, H., Berz, G., Emanuel, K., Gray, W., Landsea, C., Holland, G., Lighthill, J., Shieh, S.-L., Webster, P. and McGuffie, K. 1998. Tropical cyclones and global climate change: A post-IPCC assessment. Bulletin of the American Meteorological Society 79: 19-38.
Landsea, C.N., Pielke, R.A., Jr., Mestas-Nuņez, A.M. and Knaff, J.A. 1999. Atlantic basin hurricanes: Indices of climatic changes. Climatic Change 42: 89-129.
Pielke, R.A., JR. and Landsea, C.N. 1999. La Niņa, El Niņo, and Atlantic hurricane damages in the United States. Bulletin of the American Meteorological Society 80: 2027-2033.
Walsh, K. and Pittock, A.B. 1998. Potential changes in tropical storms, hurricanes, and extreme rainfall events as a result of climate change. Climatic Change 39: 199-213.
Wilson, R.M. 1999. Statistical aspects of major (intense) hurricanes in the Atlantic basin during the past 49 hurricane seasons (1950-1998): Implications for the current season. Geophysical Research Letters 26: 2957-2960.