Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation
Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation
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DOI：
10.1038/nature13397
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发表时间：
2014-05
期刊：
影响因子：
64.8
通讯作者：
M. Weber;P. Clark;G. Kuhn;A. Timmermann;D. Sprenk;R. Gladstone;Xu Zhang;Gerrit Lohmann;L. Menv
中科院分区：
文献类型：
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作者：
M. Weber;P. Clark;G. Kuhn;A. Timmermann;D. Sprenk;R. Gladstone;Xu Zhang;Gerrit Lohmann;L. Menv
我们对南极冰盖(AIS)在最后一次冰川盛期(26,000-19,000年前)之后的去冰川演化的理解，主要是基于几个日期准确但受时间和地理限制的陆地和浅海序列。这种稀疏性限制了我们对AIS、南半球气候和全球海平面之间主要反馈的理解。冰山漂浮碎片(国际复兴开发银行)的海洋记录提供了几乎连续的冰盖动态和可变性信号。国际复兴开发银行来自北大西洋的记录已被广泛用于重建北半球冰盖的可变性，但由于现有沉积物岩心的低分辨率和较大的测年不确定性，缺乏来自AIS南大洋的可比记录。在这里，我们介绍了两个日期准确的、高分辨率的国际复兴开发银行记录，它们捕捉到了最后一次冰川消融期间AIS可变性的空间综合信号。我们记录了20,000至9,000年前AIS不同地区冰山流量增加的八个事件，这与之前的情景形成了鲜明对比，这些情景确定AIS的主要退缩发生在融水脉冲1A之后，并持续到全新世晚期。国际复兴开发银行的最高流量出现在14,600年前，为南极对融水脉冲1A的贡献提供了第一个直接证据。用AIS淡水强迫进行的气候模型模拟发现，环极深水向极地输送、次表层变暖和AIS融化之间存在正反馈，这表明冰盖的微小扰动可以大大增强，为海平面快速上升提供了一种可能的机制。
Our understanding of the deglacial evolution of the Antarctic Ice Sheet (AIS) following the Last Glacial Maximum (26,000–19,000 years ago) is based largely on a few well-dated but temporally and geographically restricted terrestrial and shallow-marine sequences,,. This sparseness limits our understanding of the dominant feedbacks between the AIS, Southern Hemisphere climate and global sea level. Marine records of iceberg-rafted debris (IBRD) provide a nearly continuous signal of ice-sheet dynamics and variability. IBRD records from the North Atlantic Ocean have been widely used to reconstruct variability in Northern Hemisphere ice sheets, but comparable records from the Southern Ocean of the AIS are lacking because of the low resolution and large dating uncertainties in existing sediment cores. Here we present two well-dated, high-resolution IBRD records that capture a spatially integrated signal of AIS variability during the last deglaciation. We document eight events of increased iceberg flux from various parts of the AIS between 20,000 and 9,000 years ago, in marked contrast to previous scenarios which identified the main AIS retreat as occurring after meltwater pulse 1A,,,and continuing into the late Holocene epoch. The highest IBRD flux occurred 14,600 years ago, providing the first direct evidence for an Antarctic contribution to meltwater pulse 1A. Climate model simulations with AIS freshwater forcing identify a positive feedback between poleward transport of Circumpolar Deep Water, subsurface warming and AIS melt, suggesting that small perturbations to the ice sheet can be substantially enhanced, providing a possible mechanism for rapid sea-level rise.