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首页> 外文期刊>Paleoceanography >Polar Frontal Migration in the Warm Late Pliocene: Diatom Evidence From the Wilkes Land Margin, East Antarctica
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Polar Frontal Migration in the Warm Late Pliocene: Diatom Evidence From the Wilkes Land Margin, East Antarctica

机译：在温暖后期迁徙的极性正面迁移：来自威尔克斯土地利润的硅藻证据，东南南极洲

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摘要

The late Pliocene is the most recent interval in Earth's history to sustain global temperatures within the range of warming predicted for the 21st century, providing an appealing analog for the changes we might encounter in the coming century. Published global reconstructions and climate models find an average +2° summer sea surface temperature anomaly relative to modern during the 3.3-3.0 Ma interval of the late Pliocene, when atmospheric CO_2 concentrations last reached 400 ppm. Here we present a new diatom-based reconstruction of Pliocene interglacial sea surface conditions from IODP Site U1361, on the East Antarctic continental rise. We find that open ocean conditions in the mid-Pliocene became increasingly influenced by sea ice from 3.6-3.2 Ma, prior to the onset of Northern Hemisphere glaciation. This cooling trend was interrupted by a temporary southward migration of the Antarctic Polar Front, bathing U1361 in subantarctic waters during a single interglacial-marine isotope stage KM3 (3.17-3.15 Ma)-after which sea ice returned. Building on the identification of this single outlier interglacial, we have revisited earlier reconstructions to explore the response of the Southern Ocean/cryosphere system to peak late Pliocene warmth. By applying a modern chronostratigraphic framework to those low-resolution reconstructions, we identify the same frontal migration in four other cores in the Pacific sector of the Southern Ocean, documenting a major migration of the polar front during a key interval of warm climate. These new results suggest that KM3 is a crucial interval to test ice sheet stability in the context of anthropogenic warming.
机译：晚期的历史上最近的间隔是在21世纪预测的温暖范围内维持全球气温的最新间隔，为未来世纪遇到的变化提供了吸引人的模拟。出版的全球性重建和气候模型在晚期的3.3-3.0 mA间隔内相对于现代的平均+ 2°夏季海面温度异常，当大气CO_2浓度持续400ppm时。在这里，我们在东南极大陆崛起的IODP网站U1361中提出了一种新的基于硅藻基层海面状况。我们发现，在北半球冰川冰头开始之前，中小学的开放海洋越来越受到海冰的影响。这种冷却趋势被南极极性前沿的临时南方迁移中断，在单个中间海洋同位素阶段的单一地下水域中沐浴U1361，在返回的海冰后，在返回哪个海冰。建立在识别这个单一的异常方案中间，我们已经重新审视了早期的重建，以探讨南海/冰冻圈系统的响应，以达到高峰巨大的高潮温暖。通过向那些低分辨率重建应用现代计时框架，我们在南海太平洋地区的四个其他内核中确定了相同的正面迁移，记录了在温暖气候的关键间隔期间极性前面的重大迁移。这些新结果表明，KM3是在人为升温的背景下测试冰板稳定性的关键间隔。

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