Precipitation response to Heinrich Event-3 in the northern Indochina as revealed in a high-resolution speleothem record

• Published in: Journal of Asian Earth Sciences: X
• Main Authors: Nguyen, Dung Chi, Lee, Shih-Yu, Chen, Yue-Gau, Chiang, Hong-Wei, Shen, Chuan-Chou, Wang, Xianfeng, Doan, Lam Dinh, Lin, Yin
• Other Authors: Asian School of the Environment, Earth Observatory of Singapore
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: Science::Geology; Heinrich Event; Speleothem; Indian; Moe; North Atlantic
• Online Access: https://hdl.handle.net/10356/164201; https://doi.org/10.1016/j.jaesx.2022.100090

Heinrich Event-3 (HE-3) differs from other Heinrich Events (HEs) in terms of the strength of its expression in climatic records from different global localities. Here, we present new high resolution δ18O records from a composite speleothem record spanning from 31.5 to 28.4 ka within the HE-3 time interval. The record is obtained from two stalagmites collected from the Thuong Thien cave (TT), northern Vietnam, which exhibit growth rates of 0.12 to 0.68 mm/yr. The TT record shows a pronounced positive excursion of δ18O values of stalagmite in the time interval from 30.8 ka and lasted about one thousand years. Specifically, the δ18O reached maximum between ∼30.3–30.2 ka and returned to low values at 29.5 ka. Both the onset and termination phases of the excursion show gradual changes in δ18O values that form a relatively symmetric ‘V’ shape. The excursion suggests that the Indian Summer Monsoon (ISM), which modulates the climate and hydrology in the region, has endured dramatic weakening in response to HE-3. The timing and duration of the monsoonal decline are consistent with a significant slowdown of the Atlantic Meridional Ocean Circulation (AMOC), which probably drove the southward migration of the intertropical convergence zone (ITCZ) and consequently a decrease in precipitation over the Asian monsoonal region including northern Vietnam. To test the proposed mechanism, we further performed modeling simulations via an atmosphere general circulation model with a coupled slab ocean. Simulated results confirm both the scale and mechanistic connections between cooling in the North Atlantic and changes in precipitation at the Thuong Thien cave locality. Ministry of Education (MOE) Nanyang Technological University Published version This study is financially supported by the Ministry of Science and Technology (MOST), Taiwan, under grant number 107-2116-M-002-015-MY3 and MOST 103-2116-M-002-027-MY3 to Y.-G.C. XW acknowledges the funding support from Singapore Ministry of Education (MOE2019-T2-1-174) and Earth ...