Moisture variations over the past millennium characterized by Qaidam Basin tree-ring δ18O

Abstract

High-resolution tree-ring δ18O chronologies covering the last millennium, although scarce, are essential in understanding patterns of climatic changes in the northeastern region of the Qinghai-Tibetan Plateau. For this study, a tree-ring δ18O chronology with a temporal resolution of 3-years was developed from the long-lived Qilian juniper (Sabina przewalskii Kom.), extending back in time to AD 991. This long δ18O chronology was significantly correlated with the yearly δ18O in tree rings during the common period from 1800 to 2006, and was an effective proxy for relative humidity during the growing season. A low-frequency moisture pattern signified the occurrence of a slight drought during the Medieval Climate Anomaly, a marked occurrence of a wet period during the Little Ice Age, and a trend in increasing moisture levels, although lower than average, alongside the Twentieth Century warming trend. Comparisons to other hydroclimatic reconstructions indicate that this tree-ring δ18O chronology serves as a reliable paleo-humidity proxy for the Qaidam Basin as well as documenting details of past humidity levels in the region. © 2013 The Author(s).