Variation of East Asian summer monsoon since MIS3 recorded by an absolutely-dated stalagmite from north China

The high-resolution oxygen isotope sequence established upon 100 oxygen isotope samples and 8 ²³⁰Th dates from the Dragon Cave, Shanxi province, north China, provides a detailed history of East Asian summer monsoon (EASM) variation since Marine Isotope Stages (MIS) 3. The sample L8 grew discontinuously during the periods from 58.0 to 54.5 kaBP, 27.1 to 18.0 kaBP, 6.8 to 3.9 kaBP, respectively. On the orbital scale, the long-term trend of the δ¹⁸O record generally follow the North Hemisphere Insolation changes. However, the L8 δ¹⁸O value abruptly increased by 1‰ at 24.5 kaBP, indicating an abrupt weak monsoon event possibly associated with the Heinrich event 2 in the North Atlantic region. Moreover, gradual enrichment of δ¹⁸O since ~ 6 kaBP also indicates steadily weakening of EASM, responding to southward retreat of the Intertropical Convergence Zone. During the early MIS3, our record shows two millennial-scale strong summer events, analogous in timing and structure to the Greenland Dansgaard-Oeschger events 16-15. The latter event (DO15) exhibits two distinct phases, consistent with the centennial shifts in Greenland temperature changes. This relationship reveals a tight coupling between high- and low-latitude climates at sub-millennial scales, implying a role of the large-scale ocean- atmosphere circulation in linking Greenland temperature and the Asian monsoon.