Determining the spatial and temporal patterns of climate changes in China's western interior during the last 15 ka from lacustrine oxygen isotope records†

China's western interior is a climatologically complex region, where climatic conditions are primarily controlled by the westerly jet stream and the Asian monsoon system. Observations reveal that the δ18O signatures of these atmospheric elements as expressed in their meteoric waters are different, and these differences are reflected in the lacustrine systems that are ultimately fed by the meteoric waters. Empirical orthogonal function (EOF) decomposition of 17 lacustrine δ18O records from this area clearly reveals the spatial and temporal structures of climate changes during the last 15 ka. The first EOF mode, dominated by sites in the NW sector, captures the temperature effect on the variability of the δ18O dataset. We interpret the variations through time in the amplitude of this mode to be indicative of changes in summer air temperature. The second EOF mode, heavily weighted by sites in the SE sector, reveals the ‘amount effect’ on δ18O, and thus its amplitude time series indicates changes in the intensity of the Asian summer monsoon. Our EOF-based reconstructions of regional climate are generally consistent with the δ18O records of ice cores, cave speleothems and marine carbonates. Copyright © 2008 John Wiley & Sons, Ltd.