A few months have passed since our last hurricane update, and sure enough, two more interesting articles have appeared recently in leading scientific journals. Despite a relative calm over the past few years on the hurricane front, the global warming crowd continues to insist on thousands of websites that hurricanes are becoming more frequent and intense due to the ongoing buildup of greenhouse gases. Their claims are looking more silly every day, but they fully understand that some other Katrina-like disaster is always in our future, so they seem to be patiently waiting for the next major photo opportunity.

The first of the recent articles was published in the Journal of Climate by William Briggs who unlike virtually everyone else we feature does not seem affiliated with any recognizable research institution (he is William Briggs, New York, New York). If he is working by himself without the baggage that comes along with any research group, we applaud the effort. Furthermore, the Journal of Climate is published by the American Meteorological Society, and authors are held to very high standards of scientific scrutiny – we congratulate him for the effort.

Briggs reviews the recent literature on the subject of changing hurricane activity in recent decades focusing on the highly celebrated results of Emanuel suggesting that hurricanes in the North Atlantic have become more destructive in the past 30 years. Briggs notes that others “criticized the data analysis method used to demonstrate that the index was increasing by pointing out that the smoothing method used on the raw time series data was slightly flawed, that errors in the observations should lead to a less certain statement about increases, and that the wind speed adjustments used by Emanuel were too aggressive.”

Briggs collected popular and widely-used hurricane data for the North Atlantic and applied advanced (Bayesian) statistical methods to the analyses of trends in the data. Briggs reports “The conclusion to be drawn here is that there is good evidence that the number of tropical cyclones has increased, but only if one chooses the right date at which to start one’s analysis. Using start dates before around 1975 but after 1966 shows that there has been a definite linear increase. But using any start date from 1966 to about 1974 shows no increase. The rate at which hurricanes evolved from storms does not appear as sensitive to the start date in the data, and there is some evidence that this rate has decreased since at least 1966.” Briggs presents the box plots (Figure 1) for the log of storm number, track length, and power dissipation index, and concludes “There is no apparent trend.”  Read rest...

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