Two-phase structure of tropical hydroclimate during Heinrich Stadial 1 and its global implications

• Published in: Quaternary Science Reviews
• Main Authors: Huang, Jie, Wan, Shiming, Li, Anchun, Li, Tiegang
• Format: Report
• Language: English
• Published: PERGAMON-ELSEVIER SCIENCE LTD 2019
• Subjects: Sunda shelf; Tropical ITCZ; HS1; European ice sheet; AMOC; Last deglaciation; Physical Geography; Geology; Geography; Physical; Geosciences; Multidisciplinary; SOUTH CHINA SEA; ASIAN SUMMER MONSOON; LAST GLACIAL MAXIMUM; HIGH-RESOLUTION RECORD; EUROPEAN ICE-SHEET; CLIMATE VARIABILITY; PALEOENVIRONMENTAL CHANGE; OVERTURNING CIRCULATION; HEMISPHERE CLIMATE; MOISTURE TRANSPORT; Sunda; Ice Sheet; North Atlantic
• Online Access: http://ir.qdio.ac.cn/handle/337002/164876; https://doi.org/10.1016/j.quascirev.2019.105900

Previous studies have proposed that the two-phase structure of Heinrich Stadial 1 (HS1) is a ubiquitous feature. However, few studies have focused on the internal structure of HSI over a tropical domain; thus, the interhemispheric ocean-atmosphere teleconnections during HS1 are poorly defined. Here, we present high-resolution sedimentological, geochemical, and palaeoceanographic records from the core CG2 in the southern South China Sea (SCS), off the northern Sunda Shelf. The core continuously spans 9.0 -22.0 ky BP. The records suggest two episodes of increased monsoon rainfall during the pre-HS1 (similar to 19.0 -18.0 ky BP) and in the early HSI (17.5-16.1 ky BP), along with a weaker monsoon rainfall during the late HSI (16.1-14.7 ky BP). In contrast, a lower precipitation over the Flores Sea occurred during the early HSI, off the southern Sunda Shelf, followed by an enhanced precipitation runoff during the late HS1 (Muller et al., 2012). Notably, these two different precipitation phases characterise a southward Inter-tropical Convergence Zone (ITCZ) shift over the Sunda Shelf during HSI. These changes are also consistent with other monsoon records, as well as other available data from the tropical to high latitudes of both hemispheres, supporting the global scope of the twofold H51. We propose that the two episodes of intense monsoon rainfall over the northern Sunda Shelf during the pre-HS1 and the early HS1 observed in our study are closely linked to two different melting events associated with European ice sheet (EIS) retreat. We further propose that the subsequent maximum Atlantic meridional overturning circulation (AMOC) reduction and the migration of the ITCZ to its southernmost position during the late HSI are tightly connected with the destabilization of the marine-terminating ice-streams of the Laurentide ice sheet (LIS) in the North Atlantic. Tropical positive feedbacks during HS1, in turn, should have played an important role in sustaining the AMOC reduction and Northern Hemisphere (NH) stadial ...