In psychology, the increase in Autism diagnoses has three possible explanations; Autism is over-diagnosed because it is a fad, like ADD in the 1990s, more diagnoses are now made because it is better understood and therefore more accurate, or external things are creating more Autism.

So it goes with hurricanes and tropical storms.  There seem to be more of them.   At least with the third possibility, external events creating more of them, a new report in Journal of Geophysical Research-Atmospheres says there is no evidence climate change is responsible.  Instead, better detection means shorter storms, those lasting two days or less, are being counted now and were not in the past.   
By using statistical methods combined with the current understanding of the physical processes, we are unable to find support for the hypothesis that the century-scale record of short-lived tropical cyclones in the Atlantic contains a detectable real climate signal. Therefore, we interpret the long-term secular increase in short-duration North Atlantic tropical storms as likely to be substantially inflated by observing system changes over time.

Citation: Villarini, G., G. A. Vecchi, T. R. Knutson, and J. A. Smith (2011), Is the recorded increase in short-duration North Atlantic tropical storms spurious?, J. Geophys. Res., 116, D10114, doi:10.1029/2010JD015493.