January 27, 2010

Upward Trend in Hurricane Damage in China?

Filed under: Climate Extremes, Hurricanes

A recent article has appeared in the Bulletin of the American Meteorological Society regarding trends in tropical cyclone damages in China. The article was generated by three Chinese scientists from the China Meteorological Administration’s National Climate Center and Nanjing University’s Laboratory of Meteorological Disaster. The authors note that “This research was supported by Ministry of Science and Technology of the People’s Republic of China through the National Science and Technology Support Project and the National Natural Scientific Foundation of China.”

Let’s start with a key figure (Figure 1) in which Zhang et al. reveal an upward trend in damage from tropical cyclones (a.k.a., hurricanes, typhoons) over the 1983 to 2006. They note that “In addition to the heavy economic losses in individual years, the time series shown” “contains an upward trend over the past 24 yr, which is statistically significant at the 95% level. On average, the losses caused by landfalling tropical cyclones in China mainland increased by 1.19 billion yuans each year.” We could see this result spun several different ways. On one hand, we could write about how poor China is being ravaged by hurricanes fueled-up thanks to global warming. On the other hand, we could say, see, China is now the world leader in greenhouse gas emissions, and they are suffering the consequences. As we are about to see, there is a lot more to this story about increasing damages in China.


Figure 1. Estimated direct economic losses caused by landfalling tropical cyclones in billion yuans (thin, inflation adjusted to 2006) and the corresponding 5-yr running mean (thick) (from Zhang et al., 2009).

Zhang et al. begin their article noting that “Recently, the relationship between global warming and trends in tropical cyclone activity is a topic of active research and debate.” Once again, we point out that the “debate” is alive and well in so many dimensions of the climate change issue. Next they state “a power dissipation index (PDI), which is a collective effect of tropical cyclone intensity and lifetime and annual frequency” “has increased markedly in the western North Pacific (WNP) and North Atlantic (NA) basins since the mid-1970s” according to some researchers. Others “examined tropical cyclone numbers, durations, and intensities over the past 35 yr and argued that the number and proportion of intense tropical cyclones (maximum wind speeds larger than 58.6 m s-1) have increased in all tropical cyclone basins.” Zhang et al. must be World Climate Report fans as they note “However, using various tropical cyclone datasets, studies show that there are no statistically significant trends in PDI and intense hurricanes in the WNP basin”.

With respect to damages from hurricanes, the authors note that studies in the United States show “no significant trend in economic losses caused by landfall tropical cyclones” “After adjusting for inflation, wealth, and population”. With respect to China, Zhang et al. state “Because of the lack of the damage data, little is known about the societal influences of landfalling tropical cyclones in China, although it is one of the countries that is most frequently affected by landfalling tropical cyclones.” They observe “Being accompanied by strong winds, torrential rains, and high surges, tropical cyclones are the most devastating natural disasters in Chinese coastal provinces, inflicting huge losses in property and human life.”

Now for some facts that will not go over well with the global warming alarmists. Figure 2 shows the frequency of landfalling tropical cyclones, and there is clearly no upward trend whatsoever. Zhang et al. state “Over the past 24 yr, the landfalling tropical cyclones clearly show variability on interannual and interdecadal time scales, but there is no significant trend in the landfall frequency. Moreover, the years with extremely heavy economic losses did not always correspond with active landfall tropical cyclone seasons. In 1996 and 2005, which are the 2 yr with the heaviest losses, only seven and eight landfall tropical cyclones occurred, respectively. This indicates that the frequency of the landfalling tropical cyclones is not an important factor for the heavy economic losses.”


Figure 2. The frequency of landfalling tropical cyclones from 1983 to 2006 (thin) and the corresponding 5-yr running mean (from Zhang et al., 2009).

Zhang et al. also presented a plot of deaths related to tropical cyclones over the span of their study (Figure 3). The plot shows variability, but no trend upward at all. Zhang et al. comment “There is no significant trend in tropical cyclone casualties over the past 24 yr.”


Figure 3. Tropical cyclone casualties in China from 1983 to 2006 (thin) and the corresponding 5-yr running mean (from Zhang et al., 2009).

Now for the bottom line of this study. Zhang et al. remind us “As we know, the Chinese economy has been booming since the early 1980s, which coincided with the upward trend in the tropical cyclone damage. Chinese society has become more vulnerable to the effects of tropical cyclones. Although the economic losses have been adjusted by considering inflation, Chinese people today have more to lose.” The authors scaled the economic losses with the annual total gross domestic product (GDP) and with the annual GDP per capita. The found “In an average year, the landfalling tropical cyclones account for 0.38% of the annual total GDP of China.” When adjusting for GDP, they conclude “there was no overall trend in the normalized economic losses over the past 24 yr”.

At the end of the analyses, Zhang et al. sum it all up stating “The direct economic losses trended upward significantly over the past 24 yr. However, the trend disappears if considering the rapid increase of the annual total GDP of China, suggesting that the upward trend in direct economic losses is a result of Chinese economic development.”

A landfalling tropical cyclone can be a bull in the China shop – as this study shows over time, there are no more bulls and the bulls haven’t gotten any bigger, but there is now a lot more value of what’s in the China shop!

Which, of course, fits nicely into the general consensus that extreme weather damages aren’t increasing from rising temperatures, but, instead, from rising population and wealth. But don’t try to make this case to the IPCC!

Reference:

Zhang, Q., L. Wu, and Q. Liu. 2009. Tropical cyclone damages in China 1983-2006. Bulletin of the American Meteorological Society, 90, 489-495.




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