Late Pleistocene stratigraphy and paleoceanography in the Chukchi Plateau, western Arctic Ocean

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議

High-resolution CaCO3 variation of core COR-1bPC in the Conrad Rise in the Indian Sector of the East Antarctic

第3回極域科学シンポジウム　横断セッション「海・陸・氷床から探る後期新生代の南極寒冷圏環境変動」11月26日（月） 国立国語研究所 ２階講

A late medieval warm period in the Southern Ocean as a delayed response to external forcing?

International audienceOn the basis of long simulations performed with a three‐dimensional climate model, we propose an interhemispheric climate lag mechanism, involving the long‐term memory of deepwater masses. Warm anomalies, formed in the North Atlantic when warm conditions prevail at surface, are transported by the deep ocean circulation towards the Southern Ocean. There, the heat is released because of large scale upwelling, maintaining warm conditions and inducing a lagged response of about 150 years compared to the Northern Hemisphere. Model results and observations covering the first half of the second millenium suggest a delay between the temperature evolution in the Northern Hemisphere and in the Southern Ocean. The mechanism described here provides a reasonable hypothesis to explain such an interhemipsheric lag

An Ultra-High Resolution Sediment Record of Deglacial and Holocene Climate Change in East Antarctica: IODP Exp 318 Hole 1357 – The Adélie Basin

第3回極域科学シンポジウム　横断セッション「海・陸・氷床から探る後期新生代の南極寒冷圏環境変動」11月27日（火） 国立国語研究所 ２階講

Orbital-scale benthic foraminiferal oxygen isotope stratigraphy at the northern Bering Sea Slope Site U1343 (IODP Expedition 323) and its Pleistocene paleoceanographic significance

A continuous composite oxygen isotope (δ18O) stratigraphy from benthic foraminifera in the Bering Sea was reconstructed in order to provide insight into understanding sea-ice evolution in response to Northern Hemisphere Glaciation. Oxygen isotope records from multiple species of benthic foraminifera at Integrated Ocean Drilling Program (IODP) Expedition 323 Site U1343 (54°33.4'N, 176°49.0'E, water depth 1950 m) yield a highly refined orbital-scale age model spanning the last 1.2 Ma, and a refined age model between 1.2 and 2.4 Ma. An inter-species calibration was used to define species offsets and to successfully obtain a continuous composite benthic δ18O record, correlated with the global composite benthic δ18O stack curve LR04 to construct an orbital-scale age model. The consistency of the benthic δ18O stratigraphy with biostratigraphy and magnetostratigraphy confirms the reliability of both methods for constraining age. The time difference between cyclic changes in sedimentary physical properties and glacial–interglacial cycles since 0.8 Ma is notable, and suggests that physical properties alone cannot be used to construct an orbital-scale age model. Amplitude changes in physical properties and a significant drop in the linear sedimentation rate during glacials after 0.9 Ma indicate that the glacial sea-ice edge extended beyond the Bering Sea Slope (Site U1343) at this time