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大西洋南部循环的崩和快速恢复与降冰气候变化有关
J F McManus1, R Francois, J-M Gherardi
1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA. jmcmanus@whoi.edu
Nature
|April 23, 2004
概括
大西洋南部翻转循环在最后一次脱冰期间几乎停止了,特别是在海因里希事件H1.1周围. 其随后的重新加速与主要的区域变暖事件相吻合,证实了它在突然气候变化中的作用.
科学领域:
- 古海洋学是古海洋学.
- 气候科学 气候科学
- 地质化学 地质化学
背景情况:
- 大西洋南部翻转循环 (AMOC) 显著影响全球气候.
- 之前的研究推断AMOC变化来自沉积物营养代理物,但缺乏对循环速率的限制.
- 由于过去的重建方法的局限性,评估AMOC变化的气候影响一直是具有挑战性的.
研究的目的:
- 量化大西洋南部翻转循环的速度的过去变化.
- 调查AMOC动态与最后一次降冰期间气候突然变化的关系.
- 为了更准确地评估AMOC对地区和全球气候的影响.
主要方法:
- 使用231Pa/230Th比作为AMOC的动力学代理.
- 分析了来自亚热带北大西洋的沉积物核心.
- 通过测量沉积层中的放射性核化物度来重建过去的AMOC强度.
主要成果:
- 在海因里希事件H1 (17,500年前) 期间,AMOC几乎或完全被消除,并在年轻德里亚斯寒冷事件 (12,700年前) 期间下降.
- 在降冰期间,与两个最重要的区域变暖事件同时观察到快速的AMOC重新加速.
- 231Pa/230Th记录显示了AMOC变异性和气候突然变化之间的强烈相关性.
结论:
- 大西洋南部翻转循环的速度变化是突然气候变化的关键驱动因素.
- 这项研究证实了AMOC动态在调节过去气候转型中的重要作用.
- 231Pa/230Th代理为过去翻转的循环速率提供了强大的约束,改善了气候重建.
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