過去4億2000万年の二酸化炭素濃度によって制限された気候感受性
Dana L Royer1, Robert A Berner, Jeffrey Park
1Department of Earth and Environmental Sciences, Wesleyan University, Middletown, Connecticut 06459, USA. droyer@wesleyan.edu
Nature
|March 30, 2007
まとめ
大気中の二酸化炭素の倍増による地球の気温上昇である気候感受性は,4億2000万年以上にわたって1.5°Cを超えた可能性が高い. この長期的展望は,二酸化炭素が地球温暖化に及ぼす重大な影響を裏付けている.
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
- 気候モデリング
- 地球システム科学 地球システム科学
背景:
- 気候の感受性を理解することは,過去の気候変動を解釈し,将来の気候変動を予測するために不可欠です.
- 現在の見積もりは,しばしば短期的なデータに依存し,長期の気候変動を潜在的に過小評価しています.
- 以前の研究では,気候感度が1.5°Cから6.2°Cの範囲にあることが示唆されていますが,矛盾は存在しています.
研究 の 目的:
- 過去4億2000万年の長期均衡気候感受性を推定する.
- 地質的な時間スケールにおける気候感受性の強さを評価する.
- 炭素二酸化物の放射的強制を数百万年の期間で評価する.
主な方法:
- 過去4億2000万年の大気中の二酸化炭素濃度のモデル化.
- モデルアウトプットを古気候のプロキシ記録と比較する.
- 異なる地質時代の気候感受性を分析する.
主要な成果:
- 推定された長期的な気候感受性は,短期的な推定値とほぼ一致しています.
- 二酸化炭素による弱い放射的強制は,何百万年という時間尺度では極めて不可能である.
- 1.5°Cを超える気候感受性は,4億2000万年以上にわたる地球の気候システムの安定した特徴であるようです.
結論:
- 地球の気候システムは,地質的な時間における二酸化炭素強制に対する強い感受性を示しています.
- 長期的な気候感受性の推定は,将来の気候変動を理解するための重要な文脈を提供します.
- この発見は,広大な時間スケールにおける気候感受性の有意な変動性に関する仮定に異議を唱えている.
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