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Reconstructing 1000 Years of Precipitation in China
Reference
Shao, X., Huang, L., Liu, H., Liang, E., Fang, X. And Wang, L.  2005.  Reconstruction of precipitation variation from tree rings in recent 1000 years in Delingha, Qinghai.  Science in China Series D: Earth Sciences 48: 939-949.

What was done
Climate models have long predicted that global warming will increase the variability and amount of precipitation the world receives as a result of global warming.  In order to test such predictions, long-term records of the natural variability of precipitation from many places across the globe are needed to determine if recent trends are truly unprecedented and the result of global warming.  In the present study, the authors used seven Qilian juniper (Sabina przewalskii Kom.) ring-width chronologies from the northeastern part of the Qaidam Basin in the Tibetan Plateau to provide some answers for this one region of the globe, reconstructing a thousand-year history of annual precipitation.

What was learned
Annual precipitation was found to fluctuate at various intervals and to various degrees throughout the 1,000-year record.  Wetter periods occurred between 1520 to 1633 and 1933 to 2001, albeit precipitation has declined since the 1990s.  Drier periods, on the other hand, occurred between 1429 to 1519 and 1634 to 1741.  With respect to variability, the authors report that the magnitude of variation in annual precipitation was about 15 mm before 1430, increased to 30 mm between 1430 to 1850, and declined thereafter to the present.

What it means
Annual precipitation has fluctuated naturally at various time scales and to various degrees in the Qaidam Basin of the Tibetan Plateau over the past thousand years, and within this context its current status is in no way unusual or unprecedented.  This finding suggests that either (1) there is nothing unusual about the region's (or planet's) current degree of warmth, i.e., it is not unprecedented relative to that of the prior part of the past millennium, (2) unprecedented warmth does not lead to unprecedented precipitation or unprecedented precipitation variability, or (3) both of the above.  We must conclude, therefore, that the findings of this study provide absolutely no support for the climate-alarmist view of the world.  If anything, they contradict it.

Reviewed 31 August 2005