Enhanced moisture delivery into Victoria Land, East Antarctica, during the early Last Interglacial: implications for West Antarctic Ice Sheet stability
Enhanced moisture delivery into Victoria Land, East Antarctica, during the early Last Interglacial: implications for West Antarctic Ice Sheet stability
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DOI：
10.5194/cp-17-1841-2021
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发表时间：
2021-09
影响因子：
4.3
通讯作者：
Yuzhen Yan;N. Spaulding;M. Bender;E. Brook;J. Higgins;A. Kurbatov;P. Mayewski
中科院分区：
文献类型：
--
作者：
Yuzhen Yan;N. Spaulding;M. Bender;E. Brook;J. Higgins;A. Kurbatov;P. Mayewski
抽象的。 S27冰芯钻探于东南极洲艾伦山蓝冰区，位于维多利亚地南部，距现今罗斯冰架北缘约80公里。在这里，我们利用重建的 S27 累积率，覆盖 129 ka 至 116 ka 之间的末次间冰期 (LIG)（其中 ka 表示距今数千年）来推断进入该地区的水分输送。积累率基于根据冰年代学计算出的冰期-气龄差异，该差异受到冰的稳定水同位素的限制，以及基于捕获气体中 O2 氧同位素测量的改进的气体年代学。 S27的峰值积累率出现在128.2ka，接近南极洲LIG变暖的峰值。即使是最保守的估计，在 LIG 最大值期间，积累率也会出现数量级的增加，而其他南极冰芯的典型特征是冰川间冰期差异为 2 至 3 倍。虽然 S27 积累率增加的部分原因必须源于大规模大气环流的变化，但需要额外的机制来解释这种巨大的变化。我们假设 S27 记录的异常高的积雪反映了罗斯海的开放海洋条件，这是由于海冰范围减少和冰间湖尺寸增加造成的，也可能是由于在 LIG 起始点附近罗斯冰架相对于目前位置向南后退造成的。拟议的冰架退缩也将与主要来自西南极洲的 129ka 左右的海平面高位兼容。 S27积累率的峰值是短暂的，这表明如果罗斯冰架确实在早期LIG期间后退，那么它会重新前进125ka。
Abstract. The S27 ice core, drilled in the Allan Hills Blue Ice Area of East Antarctica, is located in southern Victoria Land, ∼80 km away from the present-day northern edge of the Ross Ice Shelf. Here, we utilize the reconstructed accumulation rate of S27 covering the Last Interglacial (LIG) period between 129 ka and 116 ka (where ka indicates thousands of years before present) to infer moisture transport into the region. The accumulation rate is based on the ice-age–gas-age differences calculated from the ice chronology, which is constrained by the stable water isotopes of the ice, and an improved gas chronology based on measurements of oxygen isotopes of O2 in the trapped gases. The peak accumulation rate in S27 occurred at 128.2 ka, near the peak LIG warming in Antarctica. Even the most conservative estimate yields an order-of-magnitude increase in the accumulation rate during the LIG maximum, whereas other Antarctic ice cores are typically characterized by a glacial–interglacial difference of a factor of 2 to 3. While part of the increase in S27 accumulation rates must originate from changes in the large-scale atmospheric circulation, additional mechanisms are needed to explain the large changes. We hypothesize that the exceptionally high snow accumulation recorded in S27 reflects open-ocean conditions in the Ross Sea, created by reduced sea ice extent and increased polynya size and perhaps by a southward retreat of the Ross Ice Shelf relative to its present-day position near the onset of the LIG. The proposed ice shelf retreat would also be compatible with a sea-level high stand around 129 ka significantly sourced from West Antarctica. The peak in S27 accumulation rates is transient, suggesting that if the Ross Ice Shelf had indeed retreated during the early LIG, it would have re-advanced by 125 ka.