深海のシリケートの脱氷パルスは,亜熱帯北大西洋の北大西洋に流れ込みます
A N Meckler1, D M Sigman, K A Gibson
1Geological Institute, ETH Zürich, 8092 Zürich, Switzerland. nele.meckler@erdw.ethz.ch
Nature
|March 30, 2013
まとめ
氷河期には,大気の下部にある二酸化炭素が海に蓄積された. 脱氷は,海洋循環,特に北大西洋と南大洋の変化を通じて,このCO2を放出しました.
科学分野:
- パレオセアノグラフィー
- 気候科学 気候科学
- 海洋学 海洋学とは
背景:
- 氷河期における低大気中のCO2は,南洋のダイナミクスの影響を受け,海洋内部の貯蔵と関連しています.
- 北大西洋の循環の変化と南洋の脱氷中のCO2排出を結びつける正確なメカニズムは完全に理解されていません.
研究 の 目的:
- 北大西洋の循環と南洋の脱氷中のCO2の放出との関連を調査する.
- バイオジェニックオパルの輸出記録を用いて過去の海洋学的な変化を再構築する.
主な方法:
- 北西アフリカからの生物学的オパール輸出の55万年の記録の分析.
- シリケート供給と海洋循環の変化の代理としてオパール輸出を解釈する.
主要な成果:
- 過去55万年の各氷河期の終結に際して,生体オパール輸出の最大値が顕著に観察されました.
- これらのオパール峰は,シリケートに乏しい北大西洋氷河間水 (GNAIW) の形成の減少を示しています.
- この減少は,地表水へのシリケート供給の増加を促進し,南極の転覆を促進し,CO2を放出しました.
結論:
- 北大西洋の循環の変化に起因するGNAIW形成の減少は,南洋からのCO2の脱氷放出の重要なメカニズムです.
- このプロセスは,シリケート供給の増加と海洋密度の変化を伴い,南極の転覆と大気中のCO2上昇を促進しました.
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