Inland thinning of West Antarctic Ice Sheet steered along subglacial rifts
Inland thinning of West Antarctic Ice Sheet steered along subglacial rifts
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DOI：
10.1038/nature11292
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发表时间：
2012-07-26
期刊：
影响因子：
64.8
通讯作者：
Vaughan, David G.
中科院分区：
文献类型：
--
作者：
Bingham, Robert G.;Ferraccioli, Fausto;Vaughan, David G.
目前南极西部冰盖（WAIS）的冰损失约占观测到的全球海平面上升的10%(1)。损失主要是由动态变薄造成的，在这种情况下，海洋或大气扰动对冰缘的强迫导致沿海岸线的冰加速变薄（2-5）。尽管对改进未来冰盖对全球海平面上升的贡献的预估至关重要，但由于缺乏对基底地形和冰下地质的了解，将动态变薄纳入模式受到限制，因此WAIS潜在退缩的速度和最终程度仍然难以量化。在这里，我们报告在Ferrigno冰流下发现了一个深达1.5公里的冰下盆地，它将冰盖内部与别林斯高森海边缘连接起来，它的存在深刻地影响了冰的损失。我们使用一套破冰雷达、磁力和重力测量，结合南极西部裂谷系统的更广泛发展，提出了盆地的裂谷起源。由于冰川侵蚀而过度加深的费里尼奥裂谷，在冰川极大期为邻近大陆架上的一条主要古冰流提供了补给(6)。反过来，古冰流侵蚀了“比利时”海槽，如今，它将温暖的开放海水输送回冰锋，以加强动态变薄。我们表明，别令斯豪森和阿蒙森海地区的动态变薄正沿着裂谷盆地被引导回冰盖内部。我们的结论是，横切西海边缘的裂谷盆地可以迅速将沿海扰动变化传递到内陆，从而促进冰盖的不稳定。
Current ice loss from the West Antarctic Ice Sheet (WAIS) accounts for about ten per cent of observed global sea-level rise(1). Losses are dominated by dynamic thinning, in which forcings by oceanic or atmospheric perturbations to the ice margin lead to an accelerated thinning of ice along the coastline(2-5). Although central to improving projections of future ice-sheet contributions to global sea-level rise, the incorporation of dynamic thinning into models has been restricted by lack of knowledge of basal topography and subglacial geology so that the rate and ultimate extent of potential WAIS retreat remains difficult to quantify. Here we report the discovery of a subglacial basin under Ferrigno Ice Stream up to 1.5 kilometres deep that connects the ice-sheet interior to the Bellingshausen Sea margin, and whose existence profoundly affects ice loss. We use a suite of ice-penetrating radar, magnetic and gravity measurements to propose a rift origin for the basin in association with the wider development of the West Antarctic rift system. The Ferrigno rift, overdeepened by glacial erosion, is a conduit which fed a major palaeo-ice stream on the adjacent continental shelf during glacial maxima(6). The palaeo-ice stream, in turn, eroded the 'Belgica' trough, which today routes warm open-ocean water back to the ice front(7) to reinforce dynamic thinning. We show that dynamic thinning from both the Bellingshausen and Amundsen Sea region is being steered back to the ice-sheet interior along rift basins. We conclude that rift basins that cut across the WAIS margin can rapidly transmit coastally perturbed change inland, thereby promoting ice-sheet instability.