[M-IS05] 南大洋・南極氷床が駆動する全球気候変動

[MIS05-P11] The Antarctic ice sheet and Southern Ocean dynamics during the Last Interglacial

*飯塚 睦¹、関 宰¹、山本 正伸¹、板木 拓也²、Weber Michael E.³、Raymo Maureen E. ⁴、Peck Victoria L.⁵、Williams Trevor⁶、IODP Expedition 382 scientists (1.北海道大学、2.産業技術総合研究所、3.University of Bonn、4.Lamont-Doherty Earth Observatory of Columbia University、5.British Antarctic Survey、6.Texas A&M University)

キーワード：南極氷床、南大洋、周極深層水、最終間氷期

Melting of the Antarctic ice sheet (AIS) are very likely to lead to sea level rise in future warming scenarios. Recent observations indicate that AIS mass loss is mainly caused by oceanic forcing (e.g., ocean warming and intrusion of warm Circumpolar Deep Water (CDW) onto the continental shelf of Antarctica). Thus, it is crucial to better understand ocean-ice-sheet interactions to improve projections of sea level change in the future. A better understanding of AIS and Southern Ocean (SO) dynamics during the last interglacial (LIG: 130–115 ka), during which global mean surface air temperatures are estimated to be +1ºC warmer than the preindustrial level, provides useful insight into future sea level rise. Previous studies suggested significant AIS mass loss during the LIG. However, AIS and SO dynamics during the LIG are poorly understood due to a lack of high-resolution paleoclimate records in the LIG. Here we reconstruct variability of sea surface temperature (SST), meltwater discharge, and influence of CDW with high temporal resolution (170 years) during the LIG based on analyses of geochemical and micropaleontological proxies in the marine sediment core U1536 collected from the Scotia Sea in IODP Expedition 382. Our preliminary results suggest that during the LIG, significant meltwater events are resolvable when SST and contribution of CDW mass to the other water masses increased, suggesting a causal link between oceanic change and AIS retreat. Furthermore, the timing of individual AIS mass loss events are consistent with the reported reconstruction of sea level variability during the LIG, suggesting a substantial contribution of AIS mass loss to the sea level rise (6–9 m) in the LIG.