Chinese cave records and the East Asia Summer Monsoon

Speleothem records in southeastern China provide key evidence for past environmental changes. However, the climatic interpretation of these proxies has remained a great controversy. Earlier work interprets the cave delta 18O signal associated with regional rainfall of the East Asia Summer Monsoon (EASM) or monsoon rainfall upstream of China. Recent isotope modeling supports the latter but show little correspondence between the precipitation delta 18O and rainfall in China. Here, we examine the evolution of the climate and precipitation delta 18O for the last 21,000 years in models and observations. Recognizing the regional difference of the EASM rainfall, we propose an interpretation of the Chinese delta 18O record that reconciles its representativeness of EASM and its driving mechanism of upstream depletion. The delta 18O records do represent the intensity of the EASM system. The monsoon intensity is best characterized by enhanced southerly monsoon winds, which correlate strongly with negative delta 18O over China and enhanced monsoon rainfall in northern China, as well as the continental scale Asian monsoon rainfall response in the upstream regions. (C) 2013 Elsevier Ltd. All rights reserved.