Stalagmite-inferred abrupt climate change of Asian Summer Monsoon at MIS 5a/4 transition

Abstract. The Greenland Interstadial 21 (GIS 21), one of the longest warm events during the last glacial, occurred in conjunction with the transition from marine isotope stages (MIS) 5a to 4. Precise determination of the timing and duration of this event can improve our understanding of hydroclimatic connection between low and high latitudes over this MIS boundary. Facilitated by a robust chronology with closely spaced U-Th ages, replicated sub-decadal-resolved δ¹⁸O records of two stalagmites from Sanxing Cave, Southwest China, express Asian Summer Monsoon (ASM) history from 79.0 ± 0.2 to 75.7 ± 0.2 thousand years before present (kyr BP, before AD 1950) to reveal detailed structure of MIS 5a/4 transition and Chinese Interstadial (CIS) 21. The composited Sanxing record is characterized with three centennial-scale strong monsoon peaks and a 700-yr-long weak monsoon period within the CIS 21 rebound-type event, concurrent with its counterpart of Greenland Interstadial 21 (GIS 21). This strong resemblance suggests a rapid atmospheric teleconnection between the North Atlantic and the ASM regions. The transition at the termination of the Chinese Interstadial (CIS) 21 is determined to be from 77.0 ± 0.2 to 76.6 ± 0.2 kyr BP with a mid-point at 76.8 ± 0.2 kyr BP, which is 0.5–1.0 kyr younger than the correspondent of the end of GIS 21 on GICC05modelext and AICC2012 timescales. Given its high accuracy, our Sanxing Cave chronology can become one of the potential references for chronological refinement for ice-core records.