[U-02] 人新世・第四紀の気候および水循環

[U02-04] Prolonged slowdown of ocean circulation and rapid sea-level rise during glacial Terminations

★Invited Papers

*Hsun-Ming Hu^1,2、Gianluca Marino³、María Fernanda Sánchez Goñi⁴、Eelco Rohling⁵、Teresa Rodrigues⁶、Carlos Pérez-Mejías⁷、Xiuyang Jiang⁸、J. Sakari Salonen⁹、Chieh-Ju Hsieh¹、Chuan-Chou Shen¹ (1.National Taiwan University、2.The University of Tokyo、3.Universidade de Vigo、4.Pratique des Hautes Etudes (EPHE, PSL University)、5.Utrecht University、6.Portuguese Sea and Atmosphere Institute (IPMA)、7.Xi’an Jiaotong University、8.Fujian Normal University、9.University of Helsinki)

キーワード：sea-level, speleothems, North Atlantic, Atlantic Meridional Overturning Circulation (AMOC)

During interglacial transitions (glacial terminations) in the Middle to Late Pleistocene, large-scale ice-sheet collapse and major ocean circulation reorganization occurred simultaneously. However, the mechanisms driving the extreme rates of sea-level rise during these terminations remain poorly understood. Here, we present a radiometrically constrained speleothem record from Basura Cave (Italy), spanning 380-310 thousand years before present (kyr BP), which offers new insights into the interactions among ice-sheet collapse, Atlantic Meridional Overturning Circulation (AMOC) dynamics, and sea-level rise during Termination IV (T-IV, approximately 340 kyr BP). Our multi-proxy dataset reveals millennial-scale climate perturbations linked to meltwater pulses and AMOC slowdowns. By synchronizing Basura data with North Atlantic marine archives (IODP Site U1385), we identify a prolonged 'Heinrich-like' stadial from 346 to 334 kyr BP. This stadial culminated in a peak rate of sea-level rise of 49 +/- 8 m/kyr at 333.6 +/- 0.7 kyr BP, the highest observed over the last 500,000 years. Comparing all five most recent glacial terminations, we find that ocean heat content accumulated during extended AMOC slowdowns likely facilitated rapid ice-sheet destabilization and sea-level rise when AMOC resumed. Our findings highlight the critical role of ocean-ice-sheet interactions and oceanic heat buildup in triggering abrupt climate transitions, and they offer a framework for understanding the processes behind extreme sea-level rise during glacial terminations.