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Tropical Cyclones Off the Northwestern Coast of Australia
Harper, B.A., Stroud, S.A., McCormack, M. and West, S. 2008. A review of historical tropical cyclone intensity in northwestern Australia and implications for climate change trend analysis. Australian Meteorological Magazine 57: 121-141.

What was done
Noting there is "increasing concern that anthropogenic climate change may be increasing TC [tropical cyclone] intensity," largely driven by the analyses of Emanuel (2005) and Webster et al. (2005) who "hypothesized and hinted at a likely very strong enhanced-Greenhouse related historical intensity trend," Harper et al. analyzed several "potential influences on the accuracy of estimating TC intensity over time due to increasing technology, methodology, knowledge and skill" for TCs that occurred off the coast of northwestern Australia, primarily in a band between 5 and 25S, over the period 1968/69 to 2000/01.

What was learned
The four Australian researchers show, in their words, that "a bias towards lower intensities likely exists in earlier (mainly pre-1980) TC central pressure deficit estimates of the order of at least 20 percent in 1970, reducing to around ten percent by 1980 and to five percent in 1985," reporting that "inferred temporal trends in the estimated intensity from the original data-sets are therefore significantly reduced in the objectively reviewed data-set." In fact, when all is said and done, they conclude "there is no prima facie evidence of a potential climate-change induced trend in TC intensity in northwestern Australia over the past 30 years."

What it means
As more and more data sets are carefully scrutinized for problems of the type described and evaluated by Harper et al., ever more researchers are arriving at the same general conclusion, i.e., that there has been no long-term increase in TC intensities around the world as the planet has warmed over the Little Ice Age-to-Current Warm Period transition, as may be explored in more depth by visiting our Subject Index and perusing the materials we have archived there under the general heading of Tropical Cyclones.

Emanuel, K. 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.

Reviewed 28 January 2009