始新世中期至渐新世早期格陵兰岛短暂冰川冰和泛北极海冰的证据。
Evidence for ephemeral middle Eocene to early Oligocene Greenland glacial ice and pan-Arctic sea ice.
作者信息
Tripati Aradhna, Darby Dennis
机构信息
Department of Earth, Planetary, and Space Sciences, Department of Atmospheric and Oceanic Sciences, Institute of the Environment and Sustainability, Institute of Geophysics and Planetary Physics, California Nanosystems Institute, University of California, Los Angeles, CA, 90095, USA.
European Institute of Marine Sciences (IUEM), Université de Brest, UMR 6538, Domaines Océaniques, Rue Dumont D'Urville, and IFREMER, 29280, Plouzané, France.
出版信息
Nat Commun. 2018 Mar 12;9(1):1038. doi: 10.1038/s41467-018-03180-5.
Earth's modern climate is defined by the presence of ice at both poles, but that ice is now disappearing. Therefore understanding the origin and causes of polar ice stability is more critical than ever. Here we provide novel geochemical data that constrain past dynamics of glacial ice on Greenland and Arctic sea ice. Based on accurate source determinations of individual ice-rafted Fe-oxide grains, we find evidence for episodic glaciation of distinct source regions on Greenland as far-ranging as ~68°N and ~80°N synchronous with ice-rafting from circum-Arctic sources, beginning in the middle Eocene. Glacial intervals broadly coincide with reduced CO, with a potential threshold for glacial ice stability near ~500 p.p.m.v. The middle Eocene represents the Cenozoic onset of a dynamic cryosphere, with ice in both hemispheres during transient glacials and substantial regional climate heterogeneity. A more stable cryosphere developed at the Eocene-Oligocene transition, and is now threatened by anthropogenic emissions.
地球的现代气候是由两极存在冰来定义的，但现在这些冰正在消失。因此，了解极地冰稳定性的起源和成因比以往任何时候都更加关键。在这里，我们提供了新的地球化学数据，这些数据限制了格陵兰岛冰川冰和北极海冰过去的动态变化。基于对单个冰筏载铁氧化物颗粒的精确源区确定，我们发现有证据表明，从始新世中期开始，格陵兰岛不同源区（范围从北纬约68°到约80°）的间歇性冰川作用与环北极源区的冰筏漂流同步。冰川期大致与二氧化碳减少同时出现，冰川冰稳定性的潜在阈值接近百万分之500体积分数。始新世中期代表了新生代动态冰冻圈的开始，在短暂的冰川期，两个半球都有冰，并且存在显著的区域气候异质性。在始新世 - 渐新世过渡时期形成了一个更稳定的冰冻圈，而现在它正受到人为排放的威胁。
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