Background
The authors write that "the impact of the rising sea surface temperature (SST) on tropical cyclone (TC) activity is one of the great societal and scientific concerns," and that "with the observed warming of the tropics of around 0.5°C over the past four to five decades, detecting the observed change in the TC activity may shed light on the impact of the global warming on TC activity."

What was done
In pursuit of their ultimate objective, Wang et al. examined cross-basin spatial-temporal variations of TC storm days for the Western North Pacific (WNP), the Eastern North Pacific (ENP), the North Atlantic (NAT), the North Indian Ocean (NIO), and the Southern Hemisphere Ocean (SHO) over the period 1965-2008, for which time interval pertinent satellite data were obtained from the U.S. Navy's Joint Typhoon Warning Center for the WNP, NIO and SHO, and from the U.S. NASA's National Hurricane Center for the NAT and ENP.

What was learned
The five researchers report that "over the period of 1965-2008, the global TC activity, as measured by storm days, shows a large amplitude fluctuation regulated by the El Niņo-Southern Oscillation and the Pacific Decadal Oscillation, but has no trend, suggesting that the rising temperature so far has not yet [had] an impact on the global total number of storm days," implying that "the spatial variation of SST, rather than the global mean temperature, may be more relevant to understanding the change of the global storm days."

What it means
Contrary to the climate-alarmist claim that global warming increases tropical storm activity on a global basis, the results of this study reveal that long-held contention to still be without merit, even with more than four decades of pertinent data in hand.