[M-IS10] [EJ] 南大洋・南極氷床が駆動する全球気候変動

[MIS10-05] 氷期の南極温暖イベントに対応した南大洋における海氷拡大

*池原 実¹、香月 興太²、山根 雅子³、横山 祐典³ (1.高知大学海洋コア総合研究センター、2.島根大学汽水域研究センター、3.東京大学大気海洋研究所)

キーワード：南大洋、海氷、南極温暖イベント、ハインリッヒイベント

The Southern Ocean has played an important role in the evolution of the global climate system. Area of sea ice shows a large seasonal variation in the Southern Ocean. Sea ice coverage on sea surface strongly affects the climate of the Southern Hemisphere through its impacts on the energy and gas budget, on the atmospheric circulation, on the hydrological cycle, and on the biological productivity. However, millennial-scale sea ice coverage and its impacts are not well understood. Here we show high-resolution records of sea ice-rafted debris (SIRD) and diatom assemblage to reveal a rapid change of sea ice distribution in the glacial Southern Ocean. The depositions of rock-fragment SIRD excluding volcanic glass and pumice were associated with increasing of sea-ice diatoms, suggesting that the millennial-scale events of cooling and sea-ice expansion were occurred in the glacial South Indian Ocean. The extent of sea ice in the Southern Ocean is occurred during the Antarctic isotope maximum (AIM) events, which is partly linked with the Heinrich Events in the Northern Hemisphere.