Interruption of two decades of Jakobshavn Isbrae acceleration and thinning as regional ocean cools
Interruption of two decades of Jakobshavn Isbrae acceleration and thinning as regional ocean cools
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DOI：
10.1038/s41561-019-0329-3
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发表时间：
2019-04-01
影响因子：
18.3
通讯作者：
Willis, Josh
中科院分区：
文献类型：
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作者：
Khazendar, Ala;Fenty, Ian G.;Willis, Josh
雅各布港是过去20年来格陵兰冰盖质量损失的最大来源。在此期间，它一直在后退，加速和变薄。在这里，我们使用航空测高和卫星图像显示，自2016年以来，雅各布港一直在重新推进，减缓和增厚。我们将这些变化与迪斯科湾海洋沃茨的同时冷却联系起来，这些海水溢出到伊卢利萨特冰峡湾。海湾上层250米处的海洋温度已经降到了20世纪80年代中期以来的最低水平.观测和建模将这种冷却的起源追溯到围绕格陵兰岛南半部循环的边界流中的异常冬季热量损失。海洋温度、冰下流量和冰川变异性的较长时间序列强烈表明，在2003年冰川浮舌解体后，海洋引起的前缘融化继续影响冰川动态。我们的结论是，预测雅各布港的未来海平面上升的贡献是基于冰川的几何形状是不够的，并占外部强迫是必不可少的。
Jakobshavn Isbrae has been the single largest source of mass loss from the Greenland Ice Sheet over the last 20 years. During that time, it has been retreating, accelerating and thinning. Here we use airborne altimetry and satellite imagery to show that since 2016 Jakobshavn has been re-advancing, slowing and thickening. We link these changes to concurrent cooling of ocean waters in Disko Bay that spill over into Ilulissat Icefjord. Ocean temperatures in the bay's upper 250 m have cooled to levels not seen since the mid 1980 s. Observations and modelling trace the origins of this cooling to anomalous wintertime heat loss in the boundary current that circulates around the southern half of Greenland. Longer time series of ocean temperature, subglacial discharge and glacier variability strongly suggest that ocean-induced melting at the front has continued to influence glacier dynamics after the disintegration of its floating tongue in 2003. We conclude that projections of Jakobshavn's future contribution to sea-level rise that are based on glacier geometry are insufficient, and that accounting for external forcing is indispensable.