寒い気候の極地海層化は,寒い気候の極地海層化は,寒い気候の極地海層化は,寒い気候の極地海層化は,寒い気候の極地海層化は,寒い気候の極地海層化は
Daniel M Sigman1, Samuel L Jaccard, Gerald H Haug
1Department of Geosciences, Princeton University, Princeton, New Jersey 08544, USA. sigman@princeton.edu
Nature
|March 6, 2004
まとめ
270万年前の世界的な冷却により,極地における海洋層分化が増加した. このシフトは,海洋の密度における気温の役割を弱め,層分化を高め,二酸化炭素を閉じ込めることで地球温暖化を拡大する可能性がある.
科学分野:
- 海洋学 海洋学とは
- 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,古代気候学 (paleoclimatology) とは
- 海洋地質学 海洋地質学
背景:
- 低緯度の海は,表面温度の層分化があり,深海の大気交換を制限しています.
- 北極海は,温度と塩分によって影響される複雑な密度構造を示しています.
- 温度に対する海水の密度感受性は凍結点に近いところまで低下し,寒い気候における海洋循環に影響を及ぼします.
研究 の 目的:
- プレオセンの末期における極海層化の変化を調査する.
- 地球温暖化が海洋密度構造と循環に与える影響を判断する.
- 極地層分化と地球気候の間のフィードバックメカニズムを評価する.
主な方法:
- サバークティック北太平洋と南洋の深海堆積物核の分析.
- 生物学的オパール蓄積率の測定.
- 堆積物中の窒素同位体組成の検査.
主要な成果:
- 270万年前から両半球で観察された垂直層分化の増加.
- 北半球の氷河が激化し,地球が冷たくなった.
- 冷却は弱まった温度を冷却します.
結論:
- プレオセンの後半の冷却は,温度を下げることで極海の層格化を強化した.
関連する概念動画
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