軌道強制と大気中の二酸化炭素がミオセンの氷床の膨張に及ぼす影響
Ann Holbourn1, Wolfgang Kuhnt, Michael Schulz
1Institute of Geosciences, Christian-Albrechts-University, D-24118 Kiel, Germany. ah@gpi.uni-kiel.de
Nature
|November 25, 2005
まとめ
ミオセンの中期の世界的な冷却は,二酸化炭素レベルの低下と南極の熱的隔離によって引き起こされ,氷床の急速な膨張につながった. この移行は,地球の氷河期気候への移行をマークしました.
科学分野:
- 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
- 気候のダイナミクス
- 地質海洋学 地質海洋学
背景:
- ミオセンの中期の世界的な冷却現象 (約. 13,900万年前) は,地球の"氷河"気候状態への最終的な移行を意味しています.
- 以前の仮説は,構造的循環の変化と大気中の二酸化炭素 (CO2) の変動を伴うが,堅固な堆積物証拠は欠けていた.
- 亜熱帯太平洋からの堆積物連鎖は,過去の気候動態を再構築するための重要なアーカイブを提供します.
研究 の 目的:
- ミオセンの中期の地球温暖化と南極の氷床の膨張の原因を調査する.
- 14.7~12.7百万年前の気候のプロキシ記録を高解像度で再構築する.
主な方法:
- 亜熱帯太平洋の2つの完全な堆積物核の分析.
- 軌道モデルを用いた新しい年代表の開発.
- 気候プロキシレコードの再構築.
主要な成果:
- 南極大陸の恒常的で低い夏の太陽照射は,大気中のCO2濃度の低下と一致しました.
- 南極の氷床の膨張と地球温暖化は,二酸化炭素の減少と同時に行われた.
- 南極の氷河化は急速であり,2つの傾斜周期で発生した.
- 気候強制における傾斜から偏心性の優位性への移行が観察されました.
結論:
- 大気中のCO2の減少と南極の熱的隔離は,氷床の急速な形成と地球温暖化を引き起こした可能性がある.
- 軌道特異性は,この移行期間中に気候変動のより重要な原動力となった.
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