最後の氷河期最大期における大西洋南極の転覆循環
Jean Lynch-Stieglitz1, Jess F Adkins, William B Curry
1Georgia Institute of Technology, Atlanta, GA 30332, USA. jean@eas.gatech.edu
Science (New York, N.Y.)
|April 7, 2007
まとめ
最後の氷河期最大期における大西洋南極の転覆循環は,極端に緩慢でも強化されたものでもなかった. 深大西洋の循環は,今日とは異なるもので,水留時間がわずかに長かったが,異なる深水特性と密度分布があった.
科学分野:
- 海洋学 海洋学 海洋学
- 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
- 地質化学 地質化学
背景:
- 大西洋南極転覆循環 (AMOC) は,地球の気候システムの重要な構成要素です.
- 過去のAMOC状態を理解することは,将来の気候変動を予測する上で極めて重要です.
- 最後の氷河期最大 (Last Glacial Maximum,LGM) は,現代の氷河期間の状況から大きく離れています.
研究 の 目的:
- LGMの間の大西洋の深海循環の状態を再構築する.
- LGM AMOCの強度と構造に関する以前の仮説を評価する.
- 広範な理解のために,多様な古海洋学的証拠を合成する.
主な方法:
- 深海の沈殿体内におけるウランの分解産物の分析により,深海の沈殿時間を推定する.
- 複数の水質トレーサーを含む,古海洋学的プロキシデータの解釈.
- 密度や化学組成などの深水特性の再構築.
主要な成果:
- LGMの間,大西洋の深海での滞在時間は,現在の時間よりもわずかに長かった.
- 複数のトレーサーからの証拠は,密度を含む深水特性の異なる分布を示しています.
- LGM AMOCは,極端に緩慢でもなく,近代的な流通の強化版でもなかった.
結論:
- LGM時代の深大西洋の循環は,今日の循環と著しく異なっていた.
- LGM AMOCには,水質と密度グラデーションのユニークな構成が含まれる可能性が高い.
- これらの発見は,氷河条件下における海洋循環の動態に関する私たちの理解を洗練します.
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