Background
The authors note that "changes in occurrences of natural disasters, which are possibly associated with global warming, have been receiving ever-increasing attention world wide," and that the "dust storm is one of the severe disastrous weather [phenomena] in China." In this regard, however, and in contrast to the general tenor of most climate-alarmist discussions of the issue, they say "a number of studies have shown that the spring dust storm frequency (DSF) bears a negative correlation with the local surface air temperature, and exhibits a downward trend over the past 50 years [our italics]," citing the studies of Qian et al. (2002), Zhou and Zhang (2003), Zhai and Li (2003), Zhao et al. (2004), Fan et al. (2006) and Gong et al. (2006, 2007) in support of this statement. The question they thus address is: Why is this so?

What was done
Zhu et al. explored "the long-term variation of Chinese DSF in spring (March to May), and its possible linkage with the global warming and its related circulation changes in the Northern Hemisphere," using data from 258 stations within the region surrounding Lake Baikal (70-130°E, 45-65°N) over the period 1954 to 2007.

What was learned
The authors found a "prominent warming" in recent decades, as well as "an anomalous dipole circulation pattern" in the troposphere that "consists of a warm anti-cyclone centered at 55°N and a cold cyclone centered around 30°N," that leads to "a weakening of the westerly jet stream and the atmospheric baroclinicity in northern China and Mongolian regions, which suppress the frequency of occurrence and the intensity of the Mongolian cyclones and result in the decreasing DSF in North China."

What it means
Once again, we have another case of a type of "severe disastrous weather" -- as Zhu et al. describe Chinese duststorms -- being dramatically reduced in response to the historical warming of the globe. For a whole host of other examples of this phenomenon, see Weather Extremes in our Subject Index.

References
Fan, Y.-D., Shi, P.-J., Zhu, A.-J., Gong, M.-X. and Guan, Y. 2006. Analysis of connection between dust storm and climate factors in northern China. Journal of Natural Disasters 15: 12-18.

Gong, D.-Y., Mao, R. and Fan, Y.-D. 2006. East Asian dust storm and weather disturbance: Possible links to the Arctic Oscillation. International Journal of Climatology 26: 1379-1396.

Gong, D.-Y., Mao, R., Shi, P.-J. and Fan, Y.-D. 2007. Correlation between east Asian dust storm frequency and PNA. Geophysical Research Letters 34: 10.1029/2007GL029944.

Qian, W.-H., Quan, L.-S. and Shi, S.-Y. 2002. Variations of the dust storm in China and its climatic control. Journal of Climate 15: 1216-1229.

Zhai, P.M. and Li, X.Y. 2003. On climate background of dust storms over northern China. Chinese Journal of Geophysics 58: 125-131.

Zhao, C., Dabu, X. and Li, Y. 2004. Relationship between climatic factors and dust storm frequency in Inner Mongolia of China. Geophysical Research Letters 31: 10.1029/2003GL018351.

Zhou, Z.-J. and Zhang, G.-C. 2003. Typical severe dust storms in northern China: 1954-2002. Chinese Science Bulletin 48: 1224-1228.