Firn air depletion as a precursor of Antarctic ice-shelf collapse
Firn air depletion as a precursor of Antarctic ice-shelf collapse
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DOI：
10.3189/2014jog13j183
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发表时间：
2014-01-01
影响因子：
3.4
通讯作者：
Vaughan, David G.
中科院分区：
文献类型：
--
作者：
Kuipers Munneke, Peter;Ligtenberg, Stefan R. M.;Vaughan, David G.
自20世纪70年代以来，南极半岛约20%的冰架突然、快速崩塌，导致其支流冰川大规模变薄和加速消融。大多数冰架的崩溃的主要假设是水力压裂的过程，其中充满水的裂缝被作用在裂缝尖端的静水压力打开。这一过程与通过增加融水供应而观察到的大气变暖有关。重要的是，冰架表面附近的低密度积雪层提供了一种多孔介质，融水可以在其中渗透和重新冻结，必须首先用重新冻结的融水填充，然后才能发生水力压裂。在这里，我们建立在这个概念的积雪空气耗尽的冰架崩溃的前兆，通过使用积雪模型表明，孔隙空间耗尽前冰架上的积雪层，这使得他们的崩溃，由于水力压裂。两个气候情景运行相同的模式表明，在21世纪的世纪大多数南极半岛冰架，和其他地方的一些小冰架，更容易成为崩溃后，积雪空气耗尽。如果变暖持续到22世纪，类似的枯竭将在东南极洲周围的冰架上蔓延。我们的模型进一步表明，预计降雪量的增加将在未来两个世纪内保护罗斯和菲尔希纳-罗恩冰架免受水力压裂的影响。
Since the 1970s, the sudden, rapid collapse of similar to 20% of ice shelves on the Antarctic Peninsula has led to large-scale thinning and acceleration of its tributary glaciers. The leading hypothesis for the collapse of most of these ice shelves is the process of hydrofracturing, whereby a water-filled crevasse is opened by the hydrostatic pressure acting at the crevasse tip. This process has been linked to observed atmospheric warming through the increased supply of meltwater. Importantly, the low-density firn layer near the ice-shelf surface, providing a porous medium in which meltwater can percolate and refreeze, has to be filled in with refrozen meltwater first, before hydrofracturing can occur at all. Here we build upon this notion of firn air depletion as a precursor of ice-shelf collapse, by using a firn model to show that pore space was depleted in the firn layer on former ice shelves, which enabled their collapse due to hydrofracturing. Two climate scenario runs with the same model indicate that during the 21st century most Antarctic Peninsula ice shelves, and some minor ice shelves elsewhere, are more likely to become susceptible to collapse following firn air depletion. If warming continues into the 22nd century, similar depletion will become widespread on ice shelves around East Antarctica. Our model further suggests that a projected increase in snowfall will protect the Ross and Filchner-Ronne Ice Shelves from hydrofracturing in the coming two centuries.