Summer monsoon moisture variability over China and Mongolia during the past four centuries

Abstract

A great impediment of Asian monsoon (AM) climate studies is the general lack of long-term observations of large-scale monsoon variability. Here we present a well-verified reconstruction of temporal changes in the dominant summer moisture pattern over China and Mongolia (CM), based on a network of tree-ring chronologies (1600-1991). The reconstruction reveals significant changes in the large-scale AM over the past four centuries, which coincide with dramatic episodes in Chinese history over the period of record. These episodes include the fall of the Ming Dynasty (AD 1644) and the catastrophic famine during China's Great Leap Forward (1958-1961). Overall, the reconstructed AM strength corresponds well with Northern Hemisphere temperature proxies over the past four centuries. Yet, this relationship has broken down in recent decades, raising the possibility that the major driving force of monsoon dynamics has shifted from natural to anthropogenic in nature. Copyright 2009 by the American Geophysical Union.