Speedup of Pine Island Glacier over the past several decades has made it Antarctica’s largest contributor to sea-level rise. The past speedup is largely due to grounding-line retreat in response to ocean-induced thinning that reduced ice-shelf buttressing. While speeds remained fairly steady from 2009 to late 2017, our Copernicus Sentinel 1A/B–derived velocity data show a >12% speedup over the past 3 years, coincident with a 19-km retreat of the ice shelf. We use an ice-flow model to simulate this loss, finding that accelerated calving can explain the recent speedup, independent of the grounding-line, melt-driven processes responsible for past speedups. If the ice shelf’s rapid retreat continues, it could further destabilize the glacier far sooner than would be expected due to surface- or ocean-melting processes.

过去几十年来，松岛冰川加速增长，使其成为南极洲海平面上升的最大贡献者。过去的加速主要是由于海洋引起的变薄导致冰架支撑减少而导致接地线后退。虽然从 2009 年到 2017 年底速度保持相当稳定，但我们的哥白尼哨兵 1A/B 导出的速度数据显示过去 3 年加速了 >12%，与冰架后退 19 公里同时发生。我们使用冰流模型来模拟这种损失，发现加速崩解可以解释最近的加速，而与导致过去加速的接地线、融化驱动过程无关。如果冰架继续快速后退，由于地表或海洋融化过程，冰川可能会比预期更快地进一步不稳定。