大気中の二酸化炭素濃度は,22億年前より以前にあった
1Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
Nature
|December 7, 1995
まとめ
初期の地球 初期の地球
科学分野:
- 地質科学は地質科学である.
- 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
- 大気科学 大気科学
背景:
- 地球の初期の大気組成は議論されている.
- 太陽の明るさが低いため,温暖化のためにより高い二酸化炭素 (CO2) が必要であった可能性があります.
- パレオソールは,初期の大気中の酸素 (pO2) に制限を与える.
研究 の 目的:
- 大気中の二酸化炭素 (pCO2) レベルは,27億~22億年前に制限された.
- 初期の地球の気候の調節におけるCO2の役割を調査する.
- アルケア紀後期とプロテロゾイク初期における気候モデルを再評価する.
主な方法:
- よく研究されたパレオソール (化石の気象プロファイル) の分析.
- パレオソールプロファイル内の鉄の降水パターンを調べる.
- 鉄シリケートと鉄炭酸の形成を用いてpCO2レベルを推測する.
主要な成果:
- 大気中のpCO2は10−1.4 atm (約) 未満でした. 現在のレベルの100倍).
- このレベルは,初期の地球の気候モデルによって予測されたレベルより大幅に低い.
- 炭素酸ではなくシリケートとしての鉄の再現は,限られたCO2を示しています.
結論:
- 初期の地球のCO2に対する気候感受性は,これまで考えられていたよりも高い可能性がある.
- 他の温室効果ガスは,古代の気候の調節に重要な役割を果たした可能性がある.
- この発見は,アルカイア・プロテロゾイク期の大気組成と気候に関する既存のモデルに異議を唱えている.
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