Scott Polar Research Institute (SPRI), University of Cambridge, Cambridge, CB2 1ER, UK.
Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder, 80309, CO, USA.
Nat Commun. 2019 Feb 13;10(1):730. doi: 10.1038/s41467-019-08522-5.
Global sea-level rise is caused, in part, by more rapid ice discharge from Antarctica, following the removal of the restraining forces of floating ice-shelves after their break-up. A trigger of ice-shelf break-up is thought to be stress variations associated with surface meltwater ponding and drainage, causing flexure and fracture. But until now, there have been no direct measurements of these processes. Here, we present field data from the McMurdo Ice Shelf, Antarctica, showing that the filling, to ~2 m depth, and subsequent draining, by overflow and channel incision, of four surface lakes causes pronounced and immediate ice-shelf flexure over multiple-week timescales. The magnitude of the vertical ice-shelf deflection reaches maxima of ~1 m at the lake centres, declining to zero at distances of <500 m. Our results should be used to guide development of continent-wide ice-sheet models, which currently do not simulate ice-shelf break-up due to meltwater loading and unloading.
全球海平面上升的部分原因是南极洲的冰排放速度加快，这是在浮动冰架解体后，其约束冰架的力被移除的结果。冰架解体的一个触发因素被认为是与表面融水积水和排水相关的应力变化，导致弯曲和断裂。但到目前为止，还没有对这些过程进行直接测量。在这里，我们提供了来自南极洲麦克默多冰架的实地数据，表明四个表面湖泊的积水（至2m 深度）和随后的溢出和渠道切割排水导致了显著的和即时的冰架弯曲，时间跨度为数周。冰架垂直挠度的幅度在湖泊中心达到1m 的最大值，在距离<500m 的地方降至零。我们的结果应被用于指导大陆范围的冰盖模型的开发，目前这些模型由于融水的加载和卸载而不模拟冰架解体。
