氷河期前期と最後の氷河期間の海面上昇による海洋的強制

Peter U Clark^1,2, Feng He³, Nicholas R Golledge^4,5

¹College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA. clarkp@onid.orst.edu.

Nature

|January 31, 2020

まとめ

海水位は,大西洋南側転覆循環 (AMOC) の減少による海洋温暖化の増加により,前回の脱氷期においてより速く上昇した. この強化された強制は,最後の氷期 (LIG) 中の極地の氷の損失を増加させた.

科学分野:

古代気候学
氷河学
海洋学

背景:

氷河解凍期と氷河間期間の海平面の歴史は,温室効果ガスの影響が類似しているにもかかわらず,異なる.
過去の氷河期 (LIG) の海面は現在の海面よりも高かったため,その要因を理解することは困難でした.
北極の氷床は大陸の棚に広がり海洋の圧力に敏感なことを示しています

研究の目的:

最後の2つの氷河期と氷河期間の間の海平面の歴史における実質的な違いの背後にある理由を調査する.
LIGで観測された海面の上昇,特に極地の氷床からの過剰な氷の損失を説明するために.
過去の海平面の変化における,大西洋南側転覆循環 (AMOC) と関連した海底温暖化の役割を決定する.

主な方法:

最新の2つの氷河期と氷河期間の海平面の歴史と気候強制データの分析.
AMOCの変動によって引き起こされる地表温暖化が極地の氷床の安定性に与える影響をモデル化する.
モデルアウトプットを検証するために,化石のサンゴ礁と洞窟を用いた過去の海面の再構築.

主要な成果:

前回の脱氷期におけるAMOCの減少により,地表の温暖化が増加し,海面が最後の脱氷期と比較して急速に上昇した.
LIGの間,グリーンランドと南極の氷床から氷の減少に寄与した.
LIGにおける極地の氷の過剰な減少は,氷河の静止調整と組み合わせて,世界の様々な場所での観測された相対的な海面レベルを説明します.

結論:

AMOCの減少に起因する海底の温暖化は,海平面の歴史とより高いLIGの海平面を説明する重要な要因です.
LIGはグリーンランドと南極の両方から,この海洋的な強制により,最後の脱氷の損失を上回る実質的な氷の損失を経験しました.
過去のメカニズムを理解することは進行中の気候変動と潜在的なAMOCシフトに対応して将来の海面上昇を予測するのに不可欠です

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