大気中の二酸化炭素濃度は,プレイストセンの中期移行期にわたって上昇した
Bärbel Hönisch1, N Gary Hemming, David Archer
1Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory of Columbia University, NY 10964-8000, USA.
まとめ
プレイストセンの氷河周期は4万年から10万年に変化した. この研究は,このシフト以前の安定した大気中の二酸化炭素 (CO2) レベルを明らかにし,長期的なCO2排出を主な原因として挑戦しています.
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,古代気候学 (paleoclimatology) とは
- 地質化学 地質化学
- 海洋学 海洋学とは
背景:
- プレイストセーン中期の移行期 (MPT) は,地球の氷河周期周期性における重要な変化を示した.
- この約4万年から約10万年のサイクル変化の根本的な要因は,まだ完全に理解されていません.
- 以前の仮説では,大気中のCO2の長期的減少が,MPTを誘発する可能性があると示唆されていた.
研究 の 目的:
- MPT全域における大気中の二酸化炭素 (CO2) レベルに関する長期記録を再構築する.
- 二酸化炭素の変動と氷河期のサイクルダイナミクスとの関係を調査する.
- CO2の引き下げがMPTを引き起こしたという仮説を検証するために.
主な方法:
- プランクトンのフォラミニファー殻におけるボロンイソトープの分析により,海面を越えたCO2の偏圧 (Pco2) を測定する.
- 210万年の Pco2 レコードの構築.
- 氷河期のサイクル行動とMPT前とMPT後のCO2濃度の比較.
主要な成果:
- 大気中のPco2は,MPTの前に比較的安定していました.
- 氷河期のPco2レベルは,MPT (>100万年前) 前に約31マイクロ大気以上であった.
- MPT後の氷河間Pco2レベルは,プレイストセンの後半 (<45万年前) のレベルに類似していました.
結論:
- この発見は,大気中のCO2と地球温暖化との強い関連性を裏付けている.
- MPT以前の氷河間Pco2の安定性は,CO2の漸進的な排出の理論と矛盾しています.
- 大気中の二酸化炭素の長期的減少は,中期プレイストセンの移行の主な原動力である可能性は低い.
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