Links of abrupt climate events in the eastern Hexi Corridor to Atlantic meridional overturning circulation changes during the last glacial: Magnetoclimatological evidence of the Shagou loess record

Abstract

The high-accumulation-rate eolian deposits in the eastern Hexi Corridor retain invaluable archives of rapid climatic fluctuations in the transition zone between the northwestern Chinese Loess Plateau, the Tengger Desert, and the northern foothills of the Qilian Mountains. High-resolution mineral magnetic and bulk grain size analyses for the Shagou loess–paleosol sequences since the last interglacial reveal that loess accumulation in northwestern limit of the East Asian summer monsoon is essentially continuous at multi-centennial scales, and variations in magnetic granulometry of the last glacial loess are predominated by the intensity of the East Asian winter monsoon (EAWM). Based on Greenland Ice Core Chronology, the complete recording of potentially all Dansgaard–Oeschger (D–O) cycles and Heinrich events substantiates a rapid response of the EAWM to the northern high-latitude abrupt climatic changes, regulated by the strength of the Atlantic Meridional Overturning Circulation (AMOC) and Arctic sea-ice extent. A synthesis of various high-resolution paleo-proxy records from the Northern Hemisphere further suggests the generally identical phasing of stadial–interstadial transitions and tight coupling of the atmosphere–ice–ocean system. We propose that the relatively stronger D–O signals in low-latitude tropical marine archives compared with middle-latitude land-based paleo-records may be accounted for by northward transport of heat and moisture originated from the warmest tropical oceans during interstadials, and the more significant influence of oceanic processes than that of atmospheric processes in propagating the northern high-latitude climatic signals during stadials. This study highlights the pivotal role of AMOC in modulating millennial-scale regional and global climate.