Rapid expansion of Greenland's low-permeability ice slabs
Rapid expansion of Greenland's low-permeability ice slabs
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DOI：
10.1038/s41586-019-1550-3
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发表时间：
2019-09-19
期刊：
影响因子：
64.8
通讯作者：
Abdalati, W.
中科院分区：
文献类型：
--
作者：
MacFerrin, M.;Machguth, H.;Abdalati, W.
近几十年来，融水径流加速成为格陵兰冰盖质量损失的主要机制(1-3)。在格陵兰岛的高海拔内部，多孔的积雪和冷杉积聚；这些可以吸收地表融水并抑制径流(4)，但如果有足够的水在地表附近重新冻结以限制渗滤(5,6)，则这种缓冲效果是有限的。然而，重新结冰对格陵兰岛径流的影响在很大程度上仍未量化。在这里，我们使用冰芯、雷达观测和区域气候模型来表明，最近融水的增加导致了数米厚、低渗透性“冰板”的形成，自2001年以来，这些“冰板”已将格陵兰冰盖的总径流面积扩大了26%+/-3%。尽管迄今为止，来自冰板顶部的径流使全球海平面上升的幅度增加了不到一毫米，但随着冰板向内陆扩张，这一贡献将大幅增加。气候变暖。在中等和高排放情景下，到 2100 年，冰块上的径流预计将分别导致全球海平面上升 7 至 33 毫米和 17 至 74 毫米，这大约是格陵兰岛高海拔内部估计径流的两倍（根据没有冰块的表面质量平衡模型的预测）。冰板将在增强地表融水反馈过程方面发挥重要作用，从根本上改变冰盖当前和未来的水文状况。
In recent decades, meltwater runoff has accelerated to become the dominant mechanism for mass loss in the Greenland ice sheet(1-3). In Greenland's high-elevation interior, porous snow and firn accumulate; these can absorb surface meltwater and inhibit runoff(4), but this buffering effect is limited if enough water refreezes near the surface to restrict percolation(5,6). However, the influence of refreezing on runoff from Greenland remains largely unquantified. Here we use firn cores, radar observations and regional climate models to show that recent increases in meltwater have resulted in the formation of metres-thick, low-permeability 'ice slabs' that have expanded the Greenland ice sheet's total runoff area by 26 +/- 3 per cent since 2001. Although runoff from the top of ice slabs has added less than one millimetre to global sea-level rise so far, this contribution will grow substantially as ice slabs expand inland in a warming climate. Runoff over ice slabs is set to contribute 7 to 33 millimetres and 17 to 74 millimetres to global sea-level rise by 2100 under moderate-and high-emissions scenarios, respectively-approximately double the estimated runoff from Greenland's high-elevation interior, as predicted by surface mass balance models without ice slabs. Ice slabs will have an important role in enhancing surface meltwater feedback processes, fundamentally altering the ice sheet's present and future hydrology.