Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin
Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin
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DOI：
10.1073/pnas.1512482112
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发表时间：
2015-11-17
影响因子：
11.1
通讯作者：
Levermann, Anders
中科院分区：
文献类型：
--
作者：
Feldmann, Johannes;Levermann, Anders
南极冰盖的未来演变是本世纪和未来几个世纪海平面预测中最大的不确定性。最近，卫星观测和高分辨率模拟表明，由于过去几十年基底冰架加速融化，西南极洲阿蒙森海地区开始出现冰盖不稳定。目前尚不清楚，这种局部不稳定是否会导致西南极洲海冰的全部释放，从而导致全球海平面上升3米以上，或者冰的损失是否受到冰动力和地形特征的限制。这里我们表明，在平行冰盖模式中，局部不稳定导致南极洲西部海冰的完全解体。在我们的模拟中，在5公里水平分辨率下，该区域在当前观测到的融化速率60年后失去平衡。此后，海洋冰盖的不稳定性完全展开，并没有因地形特征而停止。事实上，阿蒙森海部分的冰损失使集水区的冰分界线向费尔奇纳-罗恩和罗斯冰架转移，从而导致那里的基准线退缩。我们的模拟表明，如果阿蒙森海区域的不稳定确实已经开始，那么在未来的几个世纪到几千年里，南极洲将不可逆转地使全球海平面上升至少3米。
The future evolution of the Antarctic Ice Sheet represents the largest uncertainty in sea-level projections of this and upcoming centuries. Recently, satellite observations and high-resolution simulations have suggested the initiation of an ice-sheet instability in the Amundsen Sea sector of West Antarctica, caused by the last decades' enhanced basal ice-shelf melting. Whether this localized destabilization will yield a full discharge of marine ice from West Antarctica, associated with a global sea-level rise of more than 3 m, or whether the ice loss is limited by ice dynamics and topographic features, is unclear. Here we show that in the Parallel Ice Sheet Model, a local destabilization causes a complete disintegration of the marine ice in West Antarctica. In our simulations, at 5-km horizontal resolution, the region disequilibrates after 60 y of currently observed melt rates. Thereafter, the marine ice-sheet instability fully unfolds and is not halted by topographic features. In fact, the ice loss in Amundsen Sea sector shifts the catchment's ice divide toward the Filchner-Ronne and Ross ice shelves, which initiates grounding-line retreat there. Our simulations suggest that if a destabilization of Amundsen Sea sector has indeed been initiated, Antarctica will irrevocably contribute at least 3 m to global sea-level rise during the coming centuries to millennia.