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Extreme Precipitation Events in China's Zhujiang River Basin
Gemmer, M., Fischer, T., Jiang, T., Su, B. and Liu, L.L. 2011. Trends in precipitation extremes in the Zhujiang River Basin, South China. Journal of Climate 24: 750-761.

The Fourth Intergovernmental Panel on Climate Change (IPCC) Assessment Report (Trenberth et al., 2007), in the words of the authors, "indicates that the frequency of heavy precipitation events will very likely increase in China."

What was done
Seeking to learn how this "indication" may or may not have developed throughout South China over the period 1961-2007, Gemmer et al. focused their attention on one of China's largest river basins: the Zhujiang (Pearl River) basin, which is located within the provinces of Guangdong, Guangxi, Guizhou and Yunnan, and which drains an area of 579,000 km2 that includes the Leizhou Peninsula. This they accomplished by applying nonparametric trend tests to daily precipitation data from 192 weather stations that passed a rigorous homogeneity and quality check, analyzing "annual, monthly, and daily precipitation; annual and monthly number of rain days and precipitation intensity; annual and monthly maximum precipitation; 5-day maximum precipitation, number of rainstorms with >50 mm per day, and peaks over thresholds (90th, 95th and 99th percentiles)."

What was learned
The five Chinese researchers report that "few stations experienced trends in the precipitation indices on an annual basis." More specifically, they write that "less than 9% of all stations in the Zhujiang River basin show significant trends in annual extreme precipitation events (maximum precipitation, rainstorm days, intensive rain days, extremely intensive rain days for 90/95/99 percentile rain events)," noting also that "no spatial pattern can be detected for the stations with significant trends."

What it means
In light of the fact that "Zhang et al. (2009) also say that no trends can be detected for annual precipitation in the Zhujiang River basin," Gemmer et al. write that "we can therefore conclude that no distinct regions in the Zhujiang River basin have experienced trends for annual indices." Thus, over the period 1961-2007, when climate alarmists claim the earth warmed at a rate and to a level that was unprecedented over the past millennium or more, the precipitation projections of the IPCC for this part of the world within the context of unprecedented global warming have still not come to pass.

Trenberth, K.E., Jones, P.D., Ambenje, P., Bojariu, R., Easterling, D., Klein Tank, A., Parker, D., Rahimzadeh, F., Renwick, J.A., Rusticucci, M., Soden, B. and Zhai, P. 2007. Observations: Surface and atmospheric climate change. In: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K.B., Tignor, M. and Miller, H.L. (Eds.). Climate Change 2007: The Physical Science Basis. Cambridge University Press, New York, New York, USA.

Zhang, Q., Xu, C.-Y., Becker, S., Zhang, Z.X., Chen, Y.D. and Coulibaly, M. 2009. Trends and abrupt changes of precipitation maxima in the Pearl River basin, China. Atmospheric Science Letters 10: 132-144.

Reviewed 27 April 2011