What was done
The author notes that a number of climate models have at various times predicted increases in tropical cyclone numbers, intensities and geographical ranges.  Hence, he reviews what real-world data have to say about the subject.

What was learned
In describing the results of an earlier review of real-world evidence, Walsh notes that Henderson-Sellers et al. (1998) determined that, to that point in time, "there were no discernible trends in tropical cyclone numbers, intensities or locations from historical analyses."  After reviewing what had been learned over the following seven years, he also had to report "there is as yet no convincing evidence in the observed record of changes in tropical cyclone behaviour that can be ascribed to global warming."

Nevertheless, Walsh still believes (1) "there is likely to be some increase in maximum [our italics] tropical cyclone intensities in a warmer world," (2) "it is probable that this would be accompanied by increases in mean [our italics] tropical cyclone intensities," and (3) "these increases in intensities are likely to be accompanied by increases in peak precipitation rates of about 25%."

What it means
In spite of the total lack of real-world evidence for any warming-induced tropical cyclone changes, particularly during a century of warming that climate alarmists claim was unprecedented over perhaps the past two millennia, many people, including certain scientists, refuse to alter their model-derived views on the subject.  Instead, they say the predicted changes will likely be detected sometime in the future.  In the case of Atlantic hurricanes, Walsh puts this period of possible detection "some time after 2050," which gives the world's climate alarmists close to half a century to continue to claim as fact what real-world data clearly suggest is false.

Reference
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.