Widespread movement of meltwater onto and across Antarctic ice shelves
Widespread movement of meltwater onto and across Antarctic ice shelves
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DOI：
10.1038/nature22049
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发表时间：
2017-04-20
期刊：
影响因子：
64.8
通讯作者：
Bell, Robin E.
中科院分区：
文献类型：
--
作者：
Kingslake, Jonathan;Ely, Jeremy C.;Bell, Robin E.
地表融水流过冰盖，形成融化池，从而引发冰架崩塌(1,2)、接地冰流加速和海平面上升加剧(3-5)。南极冰盖的数值模型考虑了融水对冰架的影响，但忽略了水在冰面上的运动，预测本世纪全球海平面将上升一米(5)，以应对大气变暖(6)。为了了解水流过冰面的影响，需要对地表融水及其排水进行广泛的量化。然而，尽管对格陵兰岛进行了广泛的研究(7-10)并对南极洲的各个排水系统进行了观察(10-17)，但我们对整个南极洲的地表水文学或其将如何演变知之甚少。在这里，我们展示了融水通过地表溪流和池塘（以下简称“地表排水”）在冰盖表面广泛的排水，南至南纬 85 度，海拔高达 1,300 米。我们的研究结果基于 1973 年以来的卫星图像和 1947 年以来的航空摄影。地表排水已经持续了数十年，将水从地面冰输送到冰架上并跨越冰架长达 120 公里，为长达 80 公里的巨大融水池提供水源。随着本世纪融化速度的加快，大规模的地表排水可以将水输送到容易崩塌的冰架区域。虽然南极地表融化池塘在一些冰架上有相对详细的记录，但我们发现池塘通常构成广泛的、大规模的地表排水系统的一部分。在气候变暖的情况下，加强地表排水可能会加速未来南极冰块的流失，这可能是通过暴露岩石的范围、冰盖的融化和变薄之间的正反馈来实现的。
Surface meltwater drains across ice sheets, forming melt ponds that can trigger ice-shelf collapse(1,2), acceleration of grounded ice flow and increased sea-level rise(3-5). Numerical models of the Antarctic Ice Sheet that incorporate meltwater's impact on ice shelves, but ignore the movement of water across the ice surface, predict a metre of global sea-level rise this century(5) in response to atmospheric warming(6). To understand the impact of water moving across the ice surface a broad quantification of surface meltwater and its drainage is needed. Yet, despite extensive research in Greenland(7-10) and observations of individual drainage systems in Antarctica(10-17), we have little understanding of Antarctic-wide surface hydrology or how it will evolve. Here we show widespread drainage of meltwater across the surface of the ice sheet through surface streams and ponds (hereafter 'surface drainage') as far south as 85 degrees S and as high as 1,300 metres above sea level. Our findings are based on satellite imagery from 1973 onwards and aerial photography from 1947 onwards. Surface drainage has persisted for decades, transporting water up to 120 kilometres from grounded ice onto and across ice shelves, feeding vast melt ponds up to 80 kilometres long. Large-scale surface drainage could deliver water to areas of ice shelves vulnerable to collapse, as melt rates increase this century. While Antarctic surface melt ponds are relatively well documented on some ice shelves, we have discovered that ponds often form part of widespread, large-scale surface drainage systems. In a warming climate, enhanced surface drainage could accelerate future ice-mass loss from Antarctic, potentially via positive feedbacks between the extent of exposed rock, melting and thinning of the ice sheet.