Carbon Dioxide and Earth's Future Pursuing the ... - Magazooms

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To help resolve the discrepancies exhibited by the JTWC typhoon database, Song et al. analyzed
differences of track, intensity, frequency and the associated long-term trends of those TCs that
were simultaneously recorded and included within the best track data sets of the JTWC, the
RSMC and the STI from 1945 to 2007. This work revealed, according to them, that “though the
differences in TC tracks among these data sets are negligibly small, the JTWC data set tends to
classify TCs of category 2-3 as category 4-5, leading to an upward trend in the annual frequency
of category 4-5 TCs and the annual accumulated power dissipation index reported by Webster
et al. (2005) and Emanuel (2005).” And they add that “this trend and potential destructiveness
over the period 1977-2007 are found only with the JTWC data set,” while noting that actual
downward trends “are apparent in the RSMC and STI data sets.” In light of their findings,
therefore, plus those of the other scientists they cite, there would appear to be little doubt that
the studies of Emanuel (2005) and Webster et al. (2005) provide no evidence for what climate
alarmists long hailed as proof positive of their claim that global warming leads to more intense
tropical cyclones or hurricanes.
With respect to hurricanes occurring over the Indian Ocean, there are but two studies to
report. In the first, Harper et al. (2008) 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 25°S, over the period 1968/69 to 2000/01. This work revealed, 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 per cent in 1970, reducing to around ten per cent by
1980 and to five per cent in 1985,” and they say 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 was said and done, they concluded “there is no prima
facie evidence of a potential climate-change induced trend in TC intensity in northwestern
Australia over the past 30 years.”
Also working out of Australia, but only partly in the Indian Ocean, Hassim and Walsh (2008)
analyzed tropical cyclone best track data pertaining to severe storms of the Australian region
(5-30°S) forming off Western Australia and the Northern Territory (the western sector: 90-
135°E, Indian Ocean) and off Queensland and the Gulf of Carpentaria (the eastern sector: 135-
160°E, Pacific Ocean) for the presence of systematic intensity and duration trends over the
cyclone season periods running from 1969/1970 through 2004/2005; and in doing so, in the
words of the two Australian researchers, “substantial differences in trends [were] found
between the two sub-regions, with the number, average maximum intensity, and duration at
the severe category intensities of tropical cyclones increasing since 1980 in the west but
decreasing (in number) or exhibiting no trend (in intensity, severe category duration) in the
east.”
As Hassim and Walsh concluded, however, more study of Australian-region TCs will be required
“to unravel the causes of the clear differences between cyclone trends in the eastern and
western portions of the Australian basin.” Until then, it will remain unclear what the overall
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