Antarctica’s ice shelves help to control the flow of glacial ice as it drains into the ocean, meaning that the rate of global sea-level rise is subject to the structural integrity of these fragile, floating extensions of the ice sheet^1,2,3. Until now, data limitations have made it difficult to monitor the growth and retreat cycles of ice shelves on a large scale, and the full impact of recent calving-front changes on ice-shelf buttressing has not been understood. Here, by combining data from multiple optical and radar satellite sensors, we generate pan-Antarctic, spatially continuous coastlines at roughly annual resolution since 1997. We show that from 1997 to 2021, Antarctica experienced a net loss of 36,701 ± 1,465 square kilometres (1.9 per cent) of ice-shelf area that cannot be fully regained before the next series of major calving events, which are likely to occur in the next decade. Mass loss associated with ice-front retreat (5,874 ± 396 gigatonnes) has been approximately equal to mass change owing to ice-shelf thinning over the past quarter of a century (6,113 ± 452 gigatonnes), meaning that the total mass loss is nearly double that which could be measured by altimetry-based surveys alone. We model the impacts of Antarctica’s recent coastline evolution in the absence of additional feedbacks, and find that calving and thinning have produced equivalent reductions in ice-shelf buttressing since 2007, and that further retreat could produce increasingly significant sea-level rise in the future.

南极洲的冰架有助于控制冰川流入海洋时的流动，这意味着全球海平面上升的速度取决于这些脆弱的、漂浮的冰盖延伸部分的结构完整性^1,2,3. 到目前为止，由于数据限制，很难大规模监测冰架的生长和消退周期，而且最近的产犊前缘变化对冰架支撑的全面影响还不清楚。在这里，通过结合来自多个光学和雷达卫星传感器的数据，我们生成了自 1997 年以来大致每年分辨率的泛南极空间连续海岸线。我们表明，从 1997 年到 2021 年，南极洲经历了 36,701 ± 1,465 平方公里（1.9 %) 的冰架面积在未来十年可能发生的下一系列主要产犊事件之前无法完全恢复。与冰锋退缩相关的质量损失（5,874 ± 396 吉吨）大约等于过去 25 年冰架变薄导致的质量变化（6，113 ± 452 吉吨），这意味着总质量损失几乎是仅通过基于测高的调查所能测量的两倍。我们在没有额外反馈的情况下模拟了南极洲最近海岸线演变的影响，并发现自 2007 年以来，冰架的崩塌和变薄导致冰架支撑的同等减少，并且进一步的退缩可能导致未来海平面上升越来越显着。