大気中の二酸化炭素濃度の下限は,32億年前のことです
Angela M Hessler1, Donald R Lowe, Robert L Jones
1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115, USA. hesslera@gvsu.edu
Nature
|April 16, 2004
まとめ
古代の気候モデルでは,二酸化炭素以外にも温室効果ガスが求められるかもしれない. 古代の土壌に関する新しい研究は,以前に考えられていたよりも高い二酸化炭素レベルを示唆しているが,地球の初期の温暖化を説明するのにまだ不十分である可能性がある.
科学分野:
- * 初期の地球の研究
- *地化学について
- * 古代気候学
背景:
- * 古代の大気組成を理解することは,初期の地球の進化の鍵です.
- * 二酸化炭素とメタンは,気候に影響を与える潜在的な温室効果ガスです.
- * 過去の研究では,二酸化炭素濃度が温度のモデル要求値を下回っていることが示された.
研究 の 目的:
- * 古代の大気組成を調べるために.
- * 二酸化炭素やその他の温室効果ガスが,地球初期の温度を維持する上で果たす役割を決定する.
主な方法:
- *32億年前の河川の砂岩の風化皮の分析.
- * モデル均衡反応の応用.
- * 鉄分豊富な炭酸塩と粘土鉱物の地化学分析.
主要な成果:
- * 鉄に富んだ炭酸は,二酸化炭素の最小部分圧が現在の数倍以上であることを示しています.
- * 必要な二酸化炭素濃度は,いくつかの気候モデルで求められているレベルよりまだ低い.
- *この発見は,アーカイア熱の唯一の炭素二酸化物への依存を異視している.
結論:
- * 古代の大気中の二酸化炭素濃度は,ある推計よりも高かったかもしれない.
- *メタンやその他の温室効果ガスは,初期の地球の温度を維持する上で重要な役割を果たした可能性が高い.
- * 古代の気候規制を完全に理解するためには,さらなる研究が必要である.
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