Department of Geoscience & Remote Sensing, Delft Univeristy of Technology, 2600GA Delft, Netherlands;
Laboratoire de Glaciologie, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium.
Proc Natl Acad Sci U S A. 2020 Oct 6;117(40):24735-24741. doi: 10.1073/pnas.1912890117. Epub 2020 Sep 14.
Pine Island Glacier and Thwaites Glacier in the Amundsen Sea Embayment are among the fastest changing outlet glaciers in West Antarctica with large consequences for global sea level. Yet, assessing how much and how fast both glaciers will weaken if these changes continue remains a major uncertainty as many of the processes that control their ice shelf weakening and grounding line retreat are not well understood. Here, we combine multisource satellite imagery with modeling to uncover the rapid development of damage areas in the shear zones of Pine Island and Thwaites ice shelves. These damage areas consist of highly crevassed areas and open fractures and are first signs that the shear zones of both ice shelves have structurally weakened over the past decade. Idealized model results reveal moreover that the damage initiates a feedback process where initial ice shelf weakening triggers the development of damage in their shear zones, which results in further speedup, shearing, and weakening, hence promoting additional damage development. This damage feedback potentially preconditions these ice shelves for disintegration and enhances grounding line retreat. The results of this study suggest that damage feedback processes are key to future ice shelf stability, grounding line retreat, and sea level contributions from Antarctica. Moreover, they underline the need for incorporating these feedback processes, which are currently not accounted for in most ice sheet models, to improve sea level rise projections.
派恩艾兰冰川和斯维特冰川位于南极洲西部的阿蒙森海海湾，是变化最快的出海口冰川之一，对全球海平面有着重大影响。然而，评估这两个冰川如果继续变化会减弱多少和多快，仍然是一个主要的不确定性，因为控制它们的冰架弱化和基岩线后退的许多过程还没有被很好地理解。在这里，我们结合多源卫星图像和建模，揭示了派恩艾兰和斯维特冰架剪切带中损伤区域的快速发展。这些损伤区域由高度裂缝区域和开放裂缝组成，是这两个冰架的剪切带在过去十年中结构弱化的第一个迹象。理想化的模型结果还表明，损伤引发了一个反馈过程，其中初始冰架弱化触发了其剪切带中损伤的发展，这导致了进一步的加速、剪切和弱化，从而促进了更多的损伤发展。这种损伤反馈可能使这些冰架处于解体的前期，并增强基岩线后退。这项研究的结果表明，损伤反馈过程是未来冰架稳定性、基岩线后退和南极洲海平面贡献的关键。此外，它们强调需要纳入这些反馈过程，而目前大多数冰盖模型都没有考虑到这些过程，以提高海平面上升的预测。
