過去175万年の間,西太平洋の暖かいプールにおける安定した海面温度
Thibault de Garidel-Thoron1, Yair Rosenthal, Franck Bassinot
1Institute of Marine and Coastal Sciences-Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, USA. garidel@marine.rutgers.edu
Nature
|January 22, 2005
まとめ
地球温暖化による冷却は,プレイストセンの半ばの気候変化を説明できないかもしれない. 西太平洋の暖かいプールにおける海面温度は安定し,二酸化炭素減少仮説に異議を唱え,赤道太平洋の温度コントラストが増加したことを示唆した.
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
- 海洋学 海洋学 海洋学
- 海洋地質学 海洋地質学
背景:
- 約85万年前のプレイストセンの中期の気候変動は,氷河期の周期が4万1000年から10万年に変化した.
- この移行は,大気中の二酸化炭素 (CO2) の減少によって引き起こされる可能性がある地球温暖化に関連付けられています.
- この冷却の証拠は主に東方赤道海上流域で観察され,熱帯の暖かいプールがあまり研究されていない.
研究 の 目的:
- プレイストセーン時代に西太平洋の暖かいプールにおける海面温度 (SST) の安定性を調査する.
- 大気中の二酸化炭素濃度の減少が,プレイストセンの中期の気候転換の主な原動力であったという支配的な仮説に異議を唱えるためであった.
- 氷河周期の変化に影響を与える代替メカニズムを探求する.
主な方法:
- 過去175万年における高解像度SST記録の再構築.
- プランクトンのフォラミニフェラにおける酸素同位体とMg/Ca比の分析を活用した.
- 西太平洋の暖かいプールからの堆積物コアに焦点を当てた.
主要な成果:
- 西太平洋の暖かいプールからのSST記録は,プレイストセーン時代にわたって顕著な安定性を示しています.
- この安定性は,熱帯の放射能予算の長期的な変化を最小限にすることを意味しています.
- 東方赤道地域の調査結果とは対照的に,気候への対応における地域的な違いを示唆している.
結論:
- この研究は,大気中のCO2の漸進的な減少が85万年前以降の長い氷河周期の主な引き金であったという仮説に異議を唱える.
- 結果は,赤道太平洋全域の気温グラデーションが増加していることを示唆しています.
- この増幅された温度コントラストは,プレイストセンの半ばの気候移行に大きく影響した可能性がある.
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