プロテロゾイク期の大気中の高CO2レベルは,個々の微生物化石の分析から推定された
1Geology Department, University of Maryland, College Park, Maryland 20742-4211, USA. kaufman@geol.umd.edu
Nature
|September 19, 2003
まとめ
初期の地球 初期の地球
科学分野:
- 地質化学 地質化学
- 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
- 初期の地球科学 初期の地球科学
背景:
- 初期の地球は,現在の太陽光線よりも低い太陽光線を経験しました.
- 二酸化炭素 (CO2) やメタンなどの温室効果ガスの濃度は,居住可能な温度を維持するために高かった可能性が高い.
- 以前は,プロテロゾイク期の大気中のCO2濃度に関する経験的データが欠けていました.
研究 の 目的:
- プロテロゾーイク時代の大気中の二酸化炭素濃度の経験的な見積もりを提供するために.
- 地球の初期の気候調節における温室効果ガスとしての二酸化炭素の役割を調査する.
主な方法:
- 個々の有機壁の微生物化石における炭素同位体の分析.
- 精密な同位体測定のためのイオンマイクロプローブ技術を活用する.
- 中国北部の1.4ギガイアール前のプロテロゾイク時代のシェールから微生物化石の採掘.
主要な成果:
- 計算された炭素同位素分割は,CO2濃度が著しく上昇したことを示している.
- 大気中のCO2濃度の推定値は,現在のレベルより10~200倍高かった.
- 温室効果ガスとしての二酸化炭素は,2~2.2ギガイア前以降,メタンを上回った可能性が高い.
結論:
- 二酸化炭素は,太陽の明るさが低い初期の地球の気候を調節する上で重要な役割を果たしました.
- この発見は,初期の地球での居住性を維持する上で温室効果ガスの重要性を裏付けている.
- この研究は,高濃度のプロテロゾイク CO2 に関する最初の経験的証拠を提供します.
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