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プレオセンの温暖な期間の恒久的なエルニーニョのような状況
Michael W Wara1, Ana Christina Ravelo, Margaret L Delaney
1Ocean Sciences Department, University of California, Santa Cruz, CA 95064, USA.
まとめ
温暖な時期であるプレオセンの初期には,太平洋の深い熱帯と,現代のエルニーニョ現象に似た弱い海面温度差が特徴でした. これは,強い赤道太平洋の傾きが恒久的ではないことを示しており,エルニーニョのような条件が地球温暖化を誘発する可能性があることを示唆しています.
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
- 海洋学 海洋学とは
- 気候のダイナミクス
背景:
- プレオセンの初期 (4,500万~300万年前) は,地球上で最近最も温暖な時期でした.
- 過去の温暖な気候を理解することで,将来の気候変動の洞察が得られます.
- 赤道太平洋の海面温度 (SST) グラデーションの安定性は,気候の調節に極めて重要です.
研究 の 目的:
- 温暖なプレオセンの初期における赤道太平洋の状態を調査する.
- 初期のプレオセンの条件を現代の気候状態,特にエルニーニョ現象と比較する.
- 過去の地球温暖化におけるSSTの傾斜と大気循環の役割を評価する.
主な方法:
- 熱線深さとSSTの傾斜を復元するために,古海洋学プロキシの分析.
- 復元された初期のプレオセンの条件を,現代の観測データと比較.
- 太平洋環境と地球温暖化との関係を模索するためのモデリング研究.
主要な成果:
- 太平洋東部の熱帯は,プレオセンの初期に深かった.
- 平均的な西から東のSSTの差は,赤道太平洋全体で (1.5 +/- 0.9°C) 大幅に減少しました.
- これらの条件は,現代のエルニーニョ現象に似ている.
結論:
- 強い赤道太平洋 SST グラデーションは,永久的な気候特性がありません.
- 継続的なエルニーニョのような条件は,プレオセンの初期の地球温暖化に寄与した可能性がある.
- エルニーニョのような状態に関連したウォーカー循環の弱化は,地球温暖化を維持する重要な要因である可能性があります.
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