Troughs developed in ice-stream shear margins precondition ice shelves for ocean-driven breakup
Troughs developed in ice-stream shear margins precondition ice shelves for ocean-driven breakup
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DOI：
10.1126/sciadv.aax2215
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发表时间：
2019-10-01
期刊：
影响因子：
13.6
通讯作者：
Holschuh, Nicholas
中科院分区：
文献类型：
--
作者：
Alley, Karen E.;Scambos, Ted A.;Holschuh, Nicholas
快速流动的冰流形成的浮动冰架易于产生裂缝，并沿着其边缘的快速剪切沿着产生崩解。因此，要预测在海洋变暖的情况下未来冰架的不稳定性，以及由此产生的支撑作用减少、冰流加快和海平面上升，就需要了解使这些剪切边缘变薄和减弱的过程。在这里，我们使用卫星数据表明，高速度梯度导致表面槽沿着边缘的快速流动的冰流。这些槽平流进入冰架边缘，在那里，局部变薄的冰向上漂浮，形成基底槽。冰架下温暖海水的浮力羽流可以集中到这些基底槽中，使冰架边缘局部融化并削弱。这意味着，主要的冰盖排水是预先准备的快速撤退，以应对海洋变暖。
Floating ice shelves of fast-flowing ice streams are prone to rift initiation and calving originating along zones of rapid shearing at their margins. Predicting future ice-shelf destabilization under a warming ocean scenario, with the resultant reduced buttressing, faster ice flow, and sea-level rise, therefore requires an understanding of the processes that thin and weaken these shear margins. Here, we use satellite data to show that high velocity gradients result in surface troughs along the margins of fast-flowing ice streams. These troughs are advected into ice-shelf margins, where the locally thinned ice floats upward to form basal troughs. Buoyant plumes of warm ocean water beneath ice shelves can be focused into these basal troughs, localizing melting and weakening the ice-shelf margins. This implies that major ice sheet drainages are preconditioned for rapid retreat in response to ocean warming.