The sequence of the tree-ring chronology of the Sabina przewalskii Kom, recorded climate change information over 4600 years in the northeast of the Qinghai-Xizang Plateau.,  has appeared on the world famous journal in recent time.  

Yang Bao, a scientist at the Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI), has produced the sequence of the tree-ring chronology of the Sabina przewalskii Kom by using the improved the tree-ring climatology method. 

The tree-ring chronology is a way to analyze the historical climate change and reveal the interactions between the human activities and natural factors. 

Information, which is recorded by the tree-ring, can provide the temperature variation rules during historical warm seasons, and the change rules of the humidity and precipitation can be revealed by the information recorded by tree-ring in typical arid regions and semi-arid regions. 

Yang introduced, their research team has produced the sequence of the tree-ring chronology of the Sabina Przewalskii Kom from 2637 B. C. to 2011 A. D. in the northeast of the Qinghai-Xizang Plateau.  

The research result indicates the most humid period of the northeast of the Qinghai-Xizang Plateau is the past 10 years, 25 years and 50 years during the past 3500 years, and the obvious arid stage happened in the 4th century B.C. and the latter half of the 15th century. 

The research also founded that there is a significant correlation between the research result and the millennium temperature sequence of the northern hemisphere. The climate of the northeast Qinghai-Xizang Plateau was continuously humid during the Middle Ages, and there were obvious decadal climate fluctuations during the Little Ice Age. 

“If the temperature of the northern hemisphere continues to rise, this region will be more abundant rainfall.” Yang added. 

Otherwise, the research method in this study is different from the traditional standardized method. “We used the grouping and detrend method in different growth rates in this time.” Yang added, “This method can retain the low frequency climate signal objectively, which is recorded by the tree-ring, and this method has good potential in the application in the field of the dendroclimatology.” 

This research has appeared on the recent Proceedings of the National Academy of Sciences (PNAS).