まとめ
過去の氷河期最大南洋の原産量は今日より低かったため,大気中の二酸化炭素の削減のための生物的ポンプ仮説に異議を唱えた. 氷河期におけるCO2濃度の低下を説明するために,代替メカニズムが必要である.
科学分野:
- パレオセアノグラフィー
- マリン・バイオジオケミストリー
- 気候科学 気候科学
背景:
- 生物ポンプは,深海で炭素を吸収することで,大気中のCO2を低下させると仮定されています.
- 過去の海洋生産性を理解することは,気候モデルの検証に不可欠です.
研究 の 目的:
- 最後の氷河期最大期 (LGM) の南洋の原産物を再構築する.
- LGMの間,大気中のCO2の排出量について,生物学的ポンプの仮説を検証する.
主な方法:
- 深海の堆積物から採取した生物学的シリカの炭素と窒素の同位体の分析.
- 同じ核からのプランクトン型ホルマニフェラにおける炭素同位体の分析.
主要な成果:
- LGM期間の南洋の原産物は,ホロセーン期より低かった.
- これらの発見は,氷河期間の生物ポンプ効率の予想される増加と矛盾しています.
結論:
- 生物ポンプは,LGMの間,低大気中のCO2の主な原因ではなかったかもしれません.
- 他の海洋地域や非生物学的プロセスを含む可能性のある代替メカニズムが,氷河期CO2の減少に寄与した可能性が高い.
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