Paleolake evolution in response to climate change since middle MIS 3 inferred from Jilantai Salt Lake in the marginal regions of the ASM domain

Abstract

Little attention has been paid to climate change in the marginal regions of the Asian summer monsoon (ASM) domain since Marine Isotope Stage (MIS) 3 (60-27 cal kyr BP). Here, based on the mineralogy and grain size of a 24-m-long sediment core retrieved from Jilantai Salt Lake, we provide a paleolake evolution record from a marginal region of the ASM domain over the past 47 kyr. Our results indicate that the lake was a brackish or saline lake and that the region was relatively humid during 47–43 cal kyr BP. From 43 to 27.5 cal kyr BP, the lake salinity increased and the climate began to deteriorate. From 27.5 to 11.8 cal kyr BP, aeolian activity intensified and the climate was arid. From 11.8 to 5.6 cal kyr BP, the lake salinity continuously increased, and the climate was persistently arid. After 5.6 cal kyr BP, the lake salinity dramatically increased, the lake became a salt lake, and the climate was extremely arid. In general, the climate was semihumid in mid-late MIS 3, arid in MIS 2 (27–11.7 cal kyr BP), and hyperarid in the Holocene. This climate change pattern is apparently different from that in the regions influenced by the Asian monsoon and westerlies, indicating that the enhanced Asian monsoon or westerlies were not the main forcing mechanism driving climate change in the marginal regions of the ASM domain. Enhanced ice-albedo feedback caused by the expanded Northern Hemisphere ice volume during MIS 3 would have resulted in less net incoming solar radiation and relatively low temperatures in the mid-high-latitudes. The relatively low temperatures might have weakened the evaporation capacity of Jilantai Basin and increased south-north temperature gradients, resulting in an increase in local precipitation. Therefore, the climate was semihumid in mid-late MIS 3. The lowest Northern Hemisphere summer insolation (NHSI) combined with significantly increased ice-albedo feedback associated with the largest Northern Hemisphere ice volume would have led to a remarkable reduction in temperature, resulting in the reorganization of major atmospheric and hydrological systems in the Northern Hemisphere and an arid climate in MIS 2. Subsequently, the Northern Hemisphere ice volume nearly vanished, and the rising NHSI enhanced evaporation, thereby generating a hyperarid climate in the Holocene.