With or without greenhouse warming, variations in the climate of China can have great social, economic, strategic and physical significance. In particular, poor harvests associated with floods or droughts have affected hundreds of thousands of people, sometimes with major political consequences. Chinese climate is important to global climate in the physical sense for a number of reasons, notably the large role the Asian summer monsoon plays. To get information on Chinese climate before 1950 we must supplement these few records with other sources, namely references to climate-related phenomena in historical documents and natural archives such as ice cores and tree rings.
Preliminary results demonstrate the feasibility of our approach.
They show a surprising degree of agreement between the tree-ring and documentary records. A multi-year drought ending in 1929 is shown to be the most severe since 1600, and a tendency for droughts to occur at roughly seven year intervals is found in both types of record. We aim to reconstruct and analyze climate variability over the last 400 years in north central China, a region sensitive to variations in the monsoon circulation. We are doing this by building a regional network of tree-ring chronologies in the Qinling Mountains, south of the city of Xian. The climate signal extracted from these trees will be maximized by measuring a combination of wood density, ring width and stable isotopic ratios.