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Have Hurricane Intensities Increased as the World has Warmed?
Kossin, J.P., Knapp, K.R., Vimont, D.J., Murnane, R.J. and Harper, B.A. 2007. A globally consistent reanalysis of hurricane variability and trends. Geophysical Research Letters 34: 10.1029/2006GL028836.

So-called "best track" records of historical hurricane positions and intensities have been used to look for evidence of climate-alarmist claims of an increase in hurricane intensity as the world has warmed over the last few decades. However, Kossin et al. note that "the variability of the available data combined with long time-scale changes in the availability and quality of observing systems, reporting policies, and the methods utilized to analyze the data make the best track records inhomogeneous," and that this "known lack of homogeneity in both the data and techniques applied in the post-analyses has resulted in skepticism regarding the consistency of the best track intensity estimates."

What was done
As an important first step in confronting and resolving this problem, Kossin et al. "constructed a more homogeneous data record of hurricane intensity by first creating a new consistently analyzed global satellite data archive from 1983 to 2005 and then applying a new objective algorithm to the satellite data to form hurricane intensity estimates," after which they analyzed the resultant homogenized data for temporal trends over the period 1984-2004 for all major ocean basins and the global ocean as a whole.

What was learned
In the words of the five scientists who conducted the work, "using a homogeneous record, we were not able to corroborate the presence of upward trends in hurricane intensity over the past two decades in any basin other than the Atlantic," and they say that "since the Atlantic basin accounts for less than 15% of global hurricane activity, this result poses a challenge to hypotheses that directly relate globally increasing tropical sea surface temperatures to increases in long-term mean global hurricane intensity."

What it means
In light of the researchers' findings, which did not confirm the climate-alarmist prediction of an increase in global hurricane intensity in response to global warming, Kossin et al. conclude that "the question of whether hurricane intensity is globally trending upwards in a warming climate will likely remain a point of debate in the foreseeable future."

Reviewed 23 May 2007