カリフォルニア流の崩壊は,陸上での気候変動に関連した氷河期最大期の間に発生した
T D Herbert1, J D Schuffert, D Andreasen
1Department of Geological Sciences, Brown University, Providence, RI 02912, USA.
まとめ
カリフォルニア海岸沿いの海面温度 (SST) は,過去55万年にわたって大幅に変動しました. 氷河の温暖化は,カリフォルニア流の弱まりを示し,氷河期の軌道強制を支持しました.
科学分野:
- パレオセアノグラフィー
- 海洋地質学 海洋地質学
- 気候科学 気候科学
背景:
- アルケノン不飽和度指数は,過去の海面温度 (SST) を再構築するためのプロキシを提供します.
- カリフォルニア流は,地域の気候規制において重要な役割を果たしています.
- 氷河期と氷河期間のサイクルを理解することは,長期的な気候の動態を理解するための鍵です.
研究 の 目的:
- カリフォルニアの境界に沿った過去55万年の海面温度 (SST) を再構築する.
- SSTの変化,カリフォルニア流動の動態,氷河期のサイクルとの関係を調査する.
- 古代気候記録の地域対世界の適用性を評価する.
主な方法:
- 海洋堆積物から得られたアルケノン不飽和度指数の分析.
- 気候変化を示す植物の変化を特定するための花粉の分析.
- SST記録の旧気候データと軌道強制機構との相関.
主要な成果:
- 再構築されたSSTは,55万年にわたる大きな氷河期と氷河期間の変動 (4~8°C) を示しています.
- 氷河期間のピークは赤木の花粉と相関しており,温帯雨林の存在を示しています.
- SSTは,カリフォルニア流域の脱氷の1万~1万5千年前から温暖化しており,それは弱まった流れと変化した風系に関連しています.
結論:
- カリフォルニアの縁に沿った氷河の温暖化は,カリフォルニアの現在の弱まりの地域的な信号です.
- デビルズ・ホールのカルシート記録は,地球温暖化ではなく地域温暖化を示している.
- これらの発見は,氷河期の軌道 (ミランコビッチ) 理論を支持する.
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