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最後の氷河期の終結期における熱帯と高緯度の大西洋気温の同期性
David W Lea1, Dorothy K Pak, Larry C Peterson
1Department of Geological Sciences and Marine Science Institute, University of California, Santa Barbara, CA 93106, USA. lea@geol.ucsb.edu
Science (New York, N.Y.)
|September 6, 2003
まとめ
熱帯大西洋の海面温度 (SST) は,最後の氷河期間のグリーンランドと大気中のメタンの変化を密接に追跡した. 若いドライアスは,熱帯間の収束地帯のシフトに関連した,重要なSSTの低下を目撃しました.
科学分野:
- パレオセアノグラフィーとパレオ気候学
- マリン・ジオケミストリー (海洋地化学)
- 気候のダイナミクス
背景:
- 過去の気候の変動性と熱帯地域と高緯度の地域間の同期性を理解することは,将来の気候変動を予測するために不可欠です.
- カリアコ流域は,そのユニークな堆積環境のために,過去の海面温度 (SST) を再構築するための貴重なアーカイブを提供します.
- 最後の氷河期の終結と若いドライアスのイベントは,急速な気候変動の重要な期間を表しています.
研究 の 目的:
- 最後の氷河期の終結時に西熱帯大西洋から高解像度海面温度 (SST) レコードを生成する.
- 熱帯のSSTの変化のタイミングを,高緯度の気候プロキシと大気中のメタン濃度と比較する.
- 熱帯と高緯度の間の同期的な気候変動を誘発するメカニズムを調査する.
主な方法:
- カリアコ流域の沈殿体核から採取したプランクトン型フォラミニフェラのMg/Ca比の分析.
- 高解像度の海面温度 (SST) プロキシ記録の開発.
- SST記録の関連性は,既存のグリーンランド氷床プロジェクト2の気温と大気中のメタンの記録と相関しています.
主要な成果:
- 最後の氷河終結期における熱帯大西洋のSSTの変化は,グリーンランドの気温と大気中のメタンとの同期で,+/-30から+/-90年以内であった.
- 熱帯のSSTで3~4°Cの顕著な冷却イベントは,若いドライアス間隔の間に発生しました.
- これらの脱氷イベントのタイミングは,熱帯間の収束地帯 (ITCZ) の南への急速なシフトを示唆しています.
結論:
- 熱帯大西洋のSSTは,ヤング・ドライアスを含む最後の氷河期の主要な気候変化に迅速かつ同期的に反応しました.
- ITCZの南向きのシフトは,熱帯気温,大気中のメタン,高緯度の気候変化を結びつける可能性が高いメカニズムです.
- この研究は,急速な脱氷期間の地球の気候システムの相互接続性を強調しています.
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