[M-IS06] 南大洋・南極氷床が駆動する全球気候変動

[MIS06-P14] 720,000-year records of Antarctic and oceanic temperatures related to solar forcing and CO₂

*植村 立¹、本山 秀明²、Masson-Delmotte Valerie³、Jouzel Jean ³、川村 賢二²、東 久美子²、藤田 秀二²、倉元 隆之^2,10、平林 幹啓²、三宅 隆之²、大野 浩^4,2、藤田 耕史⁵、阿部 彩子⁶、飯塚 芳徳⁷、堀川 信一郎^7,5、五十嵐 誠²、鈴木 啓助⁸、鈴木 利孝⁹、藤井 理行² (1.琉球大学　理学部、2.国立極地研究所、3.LSCE, CEA-CNRS、4.北見工業大学、5.名古屋大学、6.東京大学、7.北海道大学、8.信州大学、9.山形大学、10.福島県環境創造センター)

キーワード：アイスコア、南極、安定同位体、氷期サイクル

The δD temperature proxy in Antarctic ice cores varies parallelly with CO₂ through glacial cycles with a puzzling asynchrony. To understand the mechanisms responsible for this association, precise and well-dated records of Antarctic and Southern Ocean temperature are needed. Here, we performed multiple isotopic analyses on an Antarctic ice core and reconstructed the records of temperature variations at this Antarctic site and the oceanic moisture source back to 720,000 years before present, which extend the longest records by 300,000 years.We found that (1) Antarctic temperature is affected by large variations in local insolation that are induced by obliquity. At the 41-kyr obliquity periodicity, the CO₂ variations display higher coherence with ocean temperature than Antarctic temperature. (2) At the obliquity periodicity band, changes in annual mean insolation were followed by changes in Antarctic temperatures, CO₂, and oceanic temperatures with phase lags. (3) the magnitude of the phase lag is minimal during low-eccentricity periods, suggesting that secular changes in the global carbon cycle and the ocean circulation modulate the phase relationship among temperatures, CO₂ and insolation.