8つの氷河周期は,南極の氷の核から始まります
Laurent Augustin1, Carlo Barbante, Piers R F Barnes
1Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS, BP 96, 38402 St Martin d'Hères Cedex, France.
Nature
|June 11, 2004
まとめ
新しい南極の氷芯は,74万年の気候の歴史を明らかにしています. この記録は,過去の氷河期間の期間がより長く,より暖かいことを示し,自然気候の変動性と温室効果ガスのサイクルに関する洞察を提供します.
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
- アイス・コア・サイエンス アイスコア・サイエンス
- 気候フィードバック
背景:
- "ヴォストーク"のような南極の氷芯は,数十万年以上にわたる重要な気候データを提供しています.
- 海洋記録は解像度が限られており,大気中の温室効果ガスの濃度を決定することはできません.
- これまでの記録は420,000年前まで遡るが,この時期以前に気候の変動が低かったことを示唆している.
研究 の 目的:
- ヴォストック・コアの届かない範囲を超えた気候記録を再構築するために.
- 過去74万年にわたる温室効果ガスの濃度と温度変動を分析するために.
- 過去の氷河期と氷河期間のサイクルを現在の氷河期間の周期と比較するために.
主な方法:
- 南極のドームCの深い氷の核の回収と分析.
- 氷層内の閉じ込められた大気ガスと同位体組成の年代測定と分析.
- ウォストーク記録を含む既存の古気候データと新しい氷芯記録の比較.
主要な成果:
- ドームCの氷芯は74万年に及ぶ気候記録を提供し,過去4つの氷河期のヴォストーク記録を裏付けている.
- 74万年前から43万年前までの期間は,氷河期間の温度はそれほど強烈ではなく,暖かい期間の期間が長かった.
- 約43万年前のターミネーションVは,現在の移行期と,気温と温室効果ガスの変化の類似性を示したが,明確なパターンを示した.
- 終結Vの後の氷河期間の期間は約2万8千年,現在の氷河期間の期間よりもかなり長かった.
結論:
- 過去の氷河期間の期間,特に第5期終結後の時期は,現在の時期よりもかなり長かった.
- 過去の温暖期間の長さは,人類による影響なしに長期にわたる安定した温暖な気候の可能性を示唆しています.
- 自然な温室効果ガスサイクルや気温変動を含む過去の気候動態を理解することは,将来の気候軌道を予測するのに不可欠です.
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