クレタ紀の超温室期における氷河化の同位体証拠
André Bornemann1, Richard D Norris, Oliver Friedrich
1Scripps Institution of Oceanography, University of California, San Diego, Geosciences Research Division, 9500 Gilman Drive, La Jolla, CA 92093-0244, USA. a.bornemann@uni-leipzig.de
まとめ
暖かいトゥロニアン期には,氷河が大きく形成されたという証拠がある. これは,過去地球温暖化現象の間,極は常に氷のない状態であったという考えに異議を唱える.
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,古代気候学 (paleoclimatology) とは
- 地質学 地質学 地質学
背景:
- トゥーロン紀 (Turonian epoch, 93.589.3 Ma) は,地球の歴史において例外的に温暖な時期であった.
- 証拠によると,この超温室効果の気候の間,氷河期が発生する可能性が示唆されています.
研究 の 目的:
- トゥーロン期における氷河の発生と範囲を調査する.
- 過去の地球温暖化イベントにおける極地氷の存在に関する仮定を再評価する.
主な方法:
- 熱帯大西洋の海洋石灰岩からの酸素同位体 (デルタ18O) データ解析.
- 海面と深海の温度変化を再構成する.
主要な成果:
- 約91.2万年前の地表と深海の同期デルタ18Oシフトは,約20万年の氷河期を暗示している.
- 推定される氷床は,現代の南極の氷冠の約半分の大きさであった.
- 氷河は,現在の超温室効果条件にもかかわらず発生した.
結論:
- 大きな氷床は,地球温暖化が極端な時期でも形成される.
- 過去の温室効果気候における氷のない極の仮定は,異議を唱える.
- トゥロニア氷河は,気候モデルと過去の気候動態を理解するための重要なデータを提供します.
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