観測された海面最低値から最後の氷河期最大値のタイミング
Yokoyama1, Lambeck, De Deckker P
1Research School of Earth Sciences, The Australian National University, Canberra, ACT.
Nature
|August 30, 2000
まとめ
ラスト・グラシアル・マキシマムでは,巨大な氷床が形成され,現在の氷床を5250万立方キロメートル上回った. この時期は約1万9千年前に結束し,氷の量は急激に10%減少した.
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
- 氷河学 氷河学とは
- 海洋地質学 海洋地質学
背景:
- 最後の氷河期最大 (Last Glacial Maximum,LGM) は,広範囲の氷床と地球全体の気温の低下によって特徴づけられました.
- LGMの氷床の量と融解のダイナミクスの直接的な推定は稀である.
研究 の 目的:
- LGMの間,陸上の氷の最大量を推定する.
- LGM氷床の初期融解段階のタイミングを決定する.
- 海面の変化と氷床質量バランスを再構築するために.
主な方法:
- オーストラリアのボナパルト湾の4つの異なる沈殿面の分析.
- 生物の集合体と沈殿物の保存を用いて,海洋および塩水状態の特定.
- 放射性炭素年代測定と,氷の量とタイミングを推定するための氷河-水分-同静的モデリング.
主要な成果:
- 陸上の氷の量は,現在より2万2000年から1万9000年の間にピークに達した.
- LGMの氷の量は,現在の地上の氷床を52.5 x 10^6 km3.5で上回った.
- 約19,000 +/- 250年前の急激な10%の氷の減少が,LGMの終わりを告げました.
結論:
- ボナパルト湾は,LGMの氷の動態を再構築するための貴重な記録を提供します.
- LGMは,顕著で比較的急速な脱氷イベントで終了しました.
- 過去の氷床の振る舞いを理解することは,将来の気候変動の影響を予測するために不可欠です.
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