500万年の南極環極電流の強度変動
Frank Lamy1,2, Gisela Winckler3,4, Helge W Arz5
1Alfred Wegener Institute (AWI) Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany. Frank.Lamy@awi.de.
Nature
|March 28, 2024
まとめ
南極環極流 (ACC) は地球温暖化で線形的な傾向を示していない. 代わりにACCの強度は逆転し 気候サイクルと関連付けられ 将来の温暖化に伴って増加する可能性があります
科学分野:
- 古代海洋学
- 気候科学
- 海洋学
背景:
- 南極環極流 (ACC) は,世界の海洋循環,気候の調節,南極の氷床の安定性にとって極めて重要です.
- 過去のACCの動態は地域によって異なるが,長期的な進化は不明である.
- 現在のACCの振る舞いは,大気圧,海洋密度,渦巻き活動によって影響されています.
研究 の 目的:
- ACCの強さの長期的な変化を再構築する.
- ACCの進化と地球温暖化との関係を調査する.
- ACCの変動要因を百万年単位で理解する
主な方法:
- 南太平洋の堆積物の分析
- 過去530万年におけるACCの強さの再構築
- 地球の冷却と氷の量を含む古気候記録との相関関係
主要な成果:
- 地球の冷却にもかかわらず,ACCの強さの線形的な傾向は観測されていません.
- ACCの強度が逆転し,プリオセンの冷却で増加し,プレイストセンの初期冷却で減少した.
- ACCの強度の変化は400,000年の偏心周期と南洋の再構成に関連しています.
- 氷河期間の弱小したACC流,オパルの堆積移転,そして減少したCO2との間の持続的なリンクは,中期プレイストセンの移行後に現れた.
結論:
- ACCの長期的な進化は複雑で 地球温暖化への単純な反応ではありません
- 南洋の再構成により,ACCの気候変動への感受性が変化した.
- 最も強いACCの流れは,温暖なプレオ-プレイストセンの間隔で発生し,温暖化とともに将来の増加の可能性を示唆しています.
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