化石植物皮質からの大気中の二酸化炭素の3億年の記録
1Department of Geological Sciences, University of Oregon, Eugene 97403-1272, USA. gregr@darkwing.uoregon.edu
Nature
|May 18, 2001
まとめ
この研究は,化石植物データを用いて,過去3億年の大気中の二酸化炭素 (CO2) レベルを再構築した. 高濃度のCO2はメソゾーイク時代に支配的であり,より温暖な気候と相関し,氷河期間の低CO2と対比する.
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
- パレオボタニーは古植物学です.
- 地質化学 地質化学
背景:
- 過去の大気中のCO2濃度の理解は,地質的な気候の動態を理解するために不可欠です.
- 現存する地球化学的プロキシは,ファネロゾーイク期CO2の変動について,幅広く,しかし不完全なイメージを提供している.
- 現在のCO2記録の矛盾は,改良された再構築方法を必要とします.
研究 の 目的:
- 大気中のCO2濃度の連続した3億年の記録を確立する.
- 二酸化炭素レベル,氷河期,そして地質的な時間における温室効果温暖化との関係を調査する.
- 新しいCO2再構築を既存のプロキシデータと比較し,潜在的な不一致を特定する.
主な方法:
- 化石のジンクゴ関連植物葉のストマタル豊富から大気中のCO2を再構成する.
- 葉のストモタ密度と成長期のCO2濃度との間に確立された相関を利用する.
- 既存の古気温記録と他のCO2プロキシ再構築との結果のクロス検証.
主要な成果:
- 二酸化炭素の低気温 (<1,000 p.p.m.v.) の2つの異なる期間を特定した. ネオゲンと初期ペルミアの氷河期と一致する.
- 一貫して高いCO2濃度 (1,0002,000 p.p.m.v.) を記録している. メソゾーイク時代を通じて,2000 p.p.m.v.を超える一時的なピークを記録した.
- メタンの爆発による炭素同位体ベースのCO2再構築における潜在的な不正確さの示唆.
結論:
- 過去3億年間は,主に高CO2状態で,氷河期に関連した短い低CO2区間によって中断されました.
- この結果は,地質学的時間尺度で気候を動かす上で,水蒸気,メタン,CO2を含む温室効果ガスの重要な役割を裏付けている.
- この研究は,堅固な古気候再構築のための多様なプロキシデータの重要性を強調しています.
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