東南極の氷床の形成と長期の不安定性
Sean P S Gulick1, Amelia E Shevenell2, Aleksandr Montelli1
1Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas 78758, USA.
Nature
|December 15, 2017
まとめ
東南極の氷床 (EAIS) はエオセーン期に相当な氷の量があり,大陸規模の形成に先立ちました. 氷河活動が温暖化に敏感であることを明らかにし,将来の海面上昇の貢献は過小評価されてい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
- 氷河学
- 海洋地質学
背景:
- 南極の氷床は5000万年以上にわたって進化したが,限られた地質学的記録は東南極の氷床 (EAIS) の理解を妨げている.
- EAISは,オーロラ亜氷河盆地で海面を下回り,気候変動に敏感であることを示唆しています.
- アウロラの氷床下流域は サブリーナ海岸に氷を流れ込みます この地域はEAISの動態を理解するのに 極めて重要です
研究 の 目的:
- 海洋地質データを用いて,東南極氷床 (EAIS) の過去の振る舞いを再構築する.
- 過去の気候変動に対するオーロラ亜氷河流域の感受性を評価する.
- 世界海面上昇に対するEAISの将来の貢献の予測を改善する.
主な方法:
- オーロラ亜氷河盆地の大陸棚の海面からの海洋地質学と地球物理学的データの分析
- 地質学的記録の年代付けは 氷河期の出来事のタイムラインを確立するために
- 過去の氷床状態を推論するために,トンネル渓谷を含む氷河の地形の解釈.
主要な成果:
- サブリーナ海岸にはエオセンの初期から中期にかけて,海底を覆う氷河が存在しており,これはオーロラ亜氷河盆地における34万年前の氷の量を示唆している.
- EAISはオリゴセーンとミオセーンで少なくとも11回,サブリナ海岸のシェルフを越えて前進し,後退した.
- 表面の融水に富んだ亜極氷河の証拠は,予測される将来の条件に似た温暖化に対する感受性を示唆しています.
結論:
- 過去のEAISの行動は海温,大気温,そして表面の融水の影響で動的でした.
- EAISは温暖化に敏感で 将来の氷の質量バランスにも影響を及ぼします
- 現在の海面上昇予測は,温暖化へのダイナミックな対応により,EAISの潜在的貢献を過小評価している可能性があります.
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