最後の脱氷期における南洋の炭素交換における役割
Andrea Burke1, Laura F Robinson
1Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program in Oceanography, Woods Hole, MA 02543, USA. aburke@whoi.edu
まとめ
脱氷期における南洋の炭素放出は,大気中のCO2に大きく影響した. 深海のサンゴの記録は,約14.6kaの主要な換気イベントを明らかにし,氷河期と氷河期間の二酸化炭素シフトを説明しています.
科学分野:
- パレオセアノグラフィー
- 気候科学 気候科学
- マリン・ジオケミストリー 海洋地化学
背景:
- 氷河期と氷河期間のサイクルにおける大気中のCO2の変動は,気候研究の重要な分野である.
- 炭素の湧き上がりと脱ガスによる大気中のCO2の調節における南洋の役割は,主要な仮説である.
研究 の 目的:
- 南大洋の長期放射性炭素記録を再構築し,氷河期と氷河期間のCO2変化の仮説を検証する.
- 南洋の深海と大気間の炭素交換のタイミングと性質を調査する.
主な方法:
- 南洋の深海サンゴの放射性炭素年代測定.
- 過去2万5千年の間,深海の海水における放射性炭素の減少を分析した.
主要な成果:
- 南洋の2万5千年の放射性炭素記録は,氷河期と初期の脱氷期の間に水が枯渇したことを示しています.
- 深い層分化と放射性炭素の枯渇は,約14万6千年前 (ka) に減少した.
- このタイミングは,南洋の大規模な換気イベントと一致し,深層の炭素を表面と大気中に転送します.
結論:
- 南大洋は,過去の気候変動の際に大気中のCO2を調節する上で重要な役割を果たしました.
- 14.6ka頃の南洋の大規模な換気イベントは,深海のサンゴの放射性炭素データによって支持されています.
- この現象は,最後の脱氷期に観測された大気中の放射性炭素の減少を説明する.
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