グリーンランドはプレイストセンの間,長い期間,ほとんど氷がありませんでした
Joerg M Schaefer1,2, Robert C Finkel1,3, Greg Balco4
1Lamont-Doherty Earth Observatory, Geochemistry, Palisades, New York 10964, USA.
Nature
|December 9, 2016
まとめ
グリーンランドの氷床 (GIS) は,プレイストセンの時代に長期間脱氷した. 新しいイソトープデータは,GISがはるかに小さかったか,長期間存在しなかったことを示唆し,以前の安定性モデルに挑戦しました.
科学分野:
- 古代気候学
- 氷河学
- 地化学
背景:
- グリーンランドの氷床 (GIS) の安定性は,世界の海面にとって極めて重要です.
- 過去のGISの安定性は,限られた古気候プロキシデータのために議論されている.
- GISの歴史を理解することは,気候変動への対応を予測するために不可欠です.
研究 の 目的:
- グリーンランドの氷床の 古代の安定性を再構築するために
- プレイストセンの長い脱氷期を調査する
- 地質学的証拠とGISの気候モデルを調和させる.
主な方法:
- 宇宙線で生成されたベリリウム-10 (10Be) とアルミニウム-26 (26Al) の同位体の分析.
- GISの頂点付近で掘削された岩底のイソトープの測定
- 氷床モデルと同位体データを比較する.
主要な成果:
- グリーンランドはプレイストセンの時代に長期にわたって氷が消えたという証拠がある.
- 同位体データは,岩盤が氷のない状態だったときに,GISが現在の量の10%未満に減少したことを示唆しています.
- 最も長い一貫したGIS安定期は110万年であり,その前に28万年以上の氷のない状態があった可能性がある.
結論:
- GISはプレイストセンの間に顕著な脱氷とほぼ完全な欠落を経験しました.
- 既存の気候モデルは,プレイストセンのGISの継続的な安定性を過大評価しています.
- 将来のGISシミュレーションは,過去の気候強制下で長期にわたる氷のない状態を組み込む必要があります.
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