Vegetation and climate changes since the middle MIS 3 inferred from a Lake Ailike pollen record, xinjiang, arid central asia

Abstract

Marine Isotope Stage (MIS) 3 is the latest interstadial to be a significant period for paleoclimate research. The mild interstadial climate in MIS 3 can shed light on studies of the current warming period. However, it is uncertain whether or not the humidity in MIS 3 exceeds that in Holocene level, and forcing mechanisms of paleoclimate evolution remains controversial. In this paper, we use pollen and AMS 14C dating data of a sediment core Ailike-2019 (4.49 m) recovered from Lake Ailike, Xinjiang in arid central Asia, to reconstruct the vegetation and climate changes in Lake Ailike over the last 40,000 years. The results show that Lake Ailike region has been dominated by desert vegetation since the middle MIS 3. The vegetation coverage shows that climate was arid in the middle MIS 3 (40.2-33.2 cal kyr BP), ameliorated during the late MIS 3 (33.2-26.7 cal kyr BP) but still dry, extremely dry during MIS 2 (26.7-12 cal kyr BP), and relatively wet during Holocene (12-0 cal kyr BP). The climate in the Holocene was wetter than in the mid-late MIS 3 in Lake Ailike, which is generally consistent with the paleoclimate records from arid central Asia and Europe. This climate pattern might be attributed to amounts of vapor transported by the westerlies and Siberian high pressure. Low/high Northern Atlantic sea-surface temperatures (SSTs) induced by decreased/increased Northern Hemisphere summer insolation resulted in westerlies transporting less/more amount of vapor to the arid central Asia during MIS 3/Holocene. Meanwhile, intensified/weakened Siberian high pressure resulting from the expanding/melting of ice sheet might induce dry/wet climate conditions in the mid-late MIS 3/the Holocene.