オリゴセンの深海の酸素イソトープの変動は,主に温度によって引き起こされる
Flavia Boscolo-Galazzo1, Victoria E Taylor2, Eirik V Galaasen2
1MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany.
まとめ
オリゴセンの気候の変化は,南極の氷の量の変化ではなく,海洋の温度によって引き起こされた. 新しく集積された同位体データは,軌道のペースで進む深海温暖化が顕著であることを明らかにし,南極の氷床の動態に関する過去の解釈を解決している.
科学分野:
- 古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは
- 海洋学 海洋学とは
- 氷河学 氷河学とは
背景:
- 海洋カルシット (δ18Ocalcite) の酸素同位体は,過去の気候と南極の氷床の振る舞いを再構築するために重要である.
- 以前の解釈は, δ18Ocalciteの記録に基づいた非常にダイナミックなオリゴセンの南極氷床を示唆しました.
- これらの解釈は,気候モデルと, δ18Ocalcite における温度の影響による氷の量の潜在的過大評価によって異議を唱える.
研究 の 目的:
- オリゴセンの深海温度の変動を,海水化学から独立して再構築する.
- 軌道のペースによる温度変化が観測された δ18Ocalciteサイクルを説明できるかどうかをテストする.
- オリゴセンの南極氷床の提案された動的振る舞いを再評価する.
主な方法:
- ベンティック・フォーアミニフェラル・クランプされた同位体温度計は,深海の温度を決定するために使用されました.
- 分析はオリゴセーン時代 (34-2300万年前) に焦点を当てた.
- 軌道変動,特に離心度は,温度に影響を及ぼすために調査されました.
主要な成果:
- 深海温度の軌道変動に関する最初のオリゴセンの記録が確立されました.
- 最大4°Cの特異なペースの大きな温度変動が確認されました.
- これらの温度変動は,大きな氷の量変化を誘発することなく,δ18Ocalciteサイクルを十分に説明します.
結論:
- オリゴセーン δ18 オカルシート周期は,海洋の気温の変化によって説明できるが,必ずしも大陸規模の氷床の変化ではない.
- 南極の氷床は,オリゴセーン時代に,これまで考えられていたよりも安定していたかもしれない.
- 深海と地球全体の気温は,より暖かいオリゴセンのような気候で日照分布に敏感です.
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