Background
Defining rapid intensification (RI) of a tropical cyclone (TC) as occurring when the maximum wind speed of a TC "reaches at least (a) 5 knots in the first 6 hours, (b) 10 knots in the first 12 hours, and (c) 30 knots in 24 hours," the authors note that "all category 4 and 5 hurricanes in the Atlantic basin and 90% of the equivalent-strength typhoons in the western North Pacific experience at least one RI process in their life cycles."

What was done
Using best-track TC data obtained from the Joint Typhoon Warning Center for the 40-year period 1965-2004, Wang and Zhou determined the climatic conditions that are most critical for the development of RI in TCs of the Western North Pacific on annual, intra-seasonal, and inter-annual time scales.

What was learned
The two researchers report that "over the past 40 years, the annual total of RI in the western North Pacific shows pronounced interdecadal variation but no significant trend," noting that this fact "implies that the super typhoons had likely no upward trend in the last 40 years." In addition, they found that "when the mean latitude, where the tropical storms form, shifted southward (either seasonally or from year to year), the proportion of super typhoon or major hurricane will increase," noting that "this finding contrasts the current notion that higher sea surface temperature leads to more frequent occurrence of category 4 or 5 hurricanes (Emanuel, 2005; Webster et al., 2005)."

What it means
Once again, we have another study based on real-world data that fails to find any support for the contention of many climate alarmists that global warming -- which is typically touted by them to have been "unprecedented" over the last decades of the 20th century -- leads to the occurrence of more and/or stronger hurricanes and typhoons.

References
Emanuel, K.A. 2005. Increasing destructiveness of tropical cyclones over the past 30 years. Nature 436: 686-688.

Webster, P.J., Holland, G.J., Curry, J.A. and Chang, H.R. 2005. Changes in tropical cyclone number, duration, and intensity in a warming environment. Science 309: 1844-1846.