A 9,000-year record of long-term climate change and abrupt climate events from Dry Lake, southern California

Dry Lake (2763 m), located in the San Bernardino Mountains of southern California, provides the first continuous record of Holocene terrestrial climate change from coastal southwestern North America. 27 AMS 14 C dates and multi-proxy analyses, including magnetic susceptibility, total organic matter, microfossil counts, and grain size are used to characterize Holocene climate trends from 9,000 cal yr B.P. to present. The results indicate the early Holocene was wettest, followed by a middle Holocene drying trend, and a dry late Holocene in response to changing insolation. Additionally, the Dry Lake record contains evidence for abrupt, short-lived climate events. The most significant event is a response to the late Holocene North Atlantic 8.2 ka event, during which summer temperature and precipitation diminished and a glacier advanced on San Gorgonio Mountain. Other, higher frequency events also occur during the Holocene but appear to result from stochastic variability in the Pacific ocean/atmosphere system.