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A Thousand-Year Drought History of China's Qilian Mountains

Paper Reviewed
Gou, X., Deng, Y., Gao, L., Chen, F., Cook, E., Yang, M. and Zhang, F. 2015. Millennium tree-ring reconstruction of drought variability in the eastern Qilian Mountains, northwest China. Climate Dynamics 45: 1761-1770.

Climate alarmists typically contend that in response to global warming, both droughts and floods become more frequent and severe. Hence, it is important to determine if long-term real-world data from various places throughout the world provide any evidence for one or the other of these two phenomena, which should be evident -- if the climate-alarmist contention is true -- over the period of time when the planet transited from the coldest interval of the current interglacial period (the Little Ice Age) to the end of the 20th century, by which time they claim the earth had warmed at a rate and to a level that was unprecedented over the past one to two millennia.

In their recent publication that sheds new light on this subject as it pertains to drought, Guo et al. (2015) introduce their study of the subject -- which was conducted within a portion of China's Qilian Mountains -- by writing that "knowledge of natural long-term drought variability is essential for water resource management and planning, especially in arid and sub-arid regions of the world." And noting that such information had been lacking for China's Qilian Mountains, they go on to describe how they created such a record for the 1,002-year period 1009-2010 based on a tree-ring chronology they developed from 179 ring-width cores extracted from 100 living Qilian juniper trees at two sites separated from each other by about 3 km within the eastern Qilian Mountains.

Based on these data, the seven scientists developed a concomitant history of the standardized precipitation and evapotranspiration index (SPEI), which was designed to take into account both precipitation and potential evapotranspiration in determining drought. And this work revealed that the 1,002-year period "contained 158 dry and 163 wet years, each accounting for about 16% of the total years." But of even greater interest, they report that "the twentieth century had only 3 drought years."

Also of note is the fact they report that "since 1894, a persistent positive trend in moisture has been recorded until the present day," which is something they say has been found to be the case "in many other tree-ring based studies in nearby regions, e.g., the middle Qilian Mountains (Yang et al., 2011), the Qaidam Basin (Zhang et al., 2003; Sheppard et al., 2004; Liu et al., 2006; Shao et al., 2010; Yang et al., 2014), central eastern Tibet (Brauning and Mantwill, 2004), the Tienshan area (Li et al., 2006) and in western and northern Mongolia (Davi et al., 2009; Pederson et al., 2013)."

On top of all that, they additionally report that "ice core records from the Guliya and Dunde in the northern Tibetan Plateau and Puruogangri in the central Tibetan Plateau all show a wetting trend in the last century," citing Yao et al. (2008) and further noting that "a 700-year history of diffuse groundwater recharge in the Badain Jaran Desert also suggests the latter half of the twentieth century was wet," citing Gates et al. (2008).

Consequently, and in consideration of the findings of all of the studies cited above, it can safely be concluded that the preponderance of real-world evidence from the noted locations in Asia does not support the climate-alarmist claim that global warming leads to the occurrence of either more frequent or more severe droughts. In fact -- and in near unanimity -- just the opposite is found to be the case: warming tends to lead to less frequent and less severe drought conditions.

References
Brauning, A. and Mantwill, B. 2004. Summer temperature and summer monsoon history on the Tibetan plateau during the last 400 years recorded by tree rings. Geophysical Research Letters 31: 10.1029/2004GL020793.

Davi, N.K., Jacoby, G.C., D'Arrigo, R.D., Baatarbileg, N., Jinbao, L. and Curtis, A.E. 2009. A tree-ring-based drought index reconstruction for far-western Mongolia: 1565-2004. International Journal of Climatology 29: 1508-1514.

Gates, J.B., Edmunds, W.M., Ma, J. and Sheppard, P.R. 2008. A 700-year history of groundwater recharge in the drylands of NW China. The Holocene 18: 1045-1054.

Li, J., Gou, X., Cook, E.R. and Chen, F. 2006. Tree-ring based drought reconstruction for the central Tien Shan area in northwest China. Geophysical Research Letters 33: 10.1029/2006GL025803.

Liu, Y. An, Z., Ma, H., Cai, Q. and Liu, Z. 2006. Precipitation variation in the northeastern Tibetan Plateau recorded by the tree rings since 850 AD and its relevance to the Northern Hemisphere temperature. Science China Series D 49: 408-420.

Pederson, N., Leland, C., Nachin, B., Hessl, A.E., Bell, A.R., Martin-Benito, D., Saladyga, T., Suran, B., Brown, P.M. and Davi, N.K. 2013. Three centuries of shifting hydroclimatic regimes across the Mongolian Breadbasket. Agricultural and Forest Meteorology 178-179: 10-20.

Shao, X., Xu, Y., Yin, Z.Y., Liang, E., Zhu, H. and Wang, S. 2010. Climatic implications of a 3585-year tree-ring width chronology from the northeastern Qinghai-Tibetan Plateau Quaternary Science Reviews 29: 2111-2122.

Sheppard, P.R., Tarasov, P.E., Graumlich, L.J., Heussner, K.-U., Wagner, M., Osterle, H. and Thompson, L.G. 2004. Annual precipitation since 515 BC reconstructed from living and fossil juniper growth of northeastern Qinghai Province, China. Climate Dynamics 23: 869-881.

Yang, B., Qin, C., Shi, F. and Sonechkin, D.M. 2011. Tre ring-based annual streamflow reconstruction for the Heihe River in arid northwestern China from AD 575 and its implications for water resource management. The Holocene 22: 773-784.

Yang, B., Qin, C., Wang, J., He, M., Melvin, T.M., Osborn, T.J. and Briffa, K.R. 2014. A 3,500-year tree-ring record of annual precipitation on the northeastern Tibetan Plateau. Proceedings of the National Academy of Science USA 111: 2903-2908.

Yao, T., Duan, K., Xu, B., Wang, N., Guo, X. nd Yang, X. 2008. Precipitation record since AD 1600 from ice cores on the central Tibetan Plateau. Climate of the Past 4: 175-180.

Zhang, Q., Cheng, G., Yao, T., Kang, X. and Huang, J. 2003. A 2,326-year tree-ring record of climate variability on the northeastern Qinghai-Tibetan Plateau. Geophysical Research Letters 30: 10.1029/2003GL017425.

Posted 24 February 2016