Change in Antarctic Ice Shelf Area from 2009 to 2019

Antarctic Ice Shelves provide buttressing support to the ice sheet, stabilising the flow of grounded ice and its contribution to global sea levels. Over the past 50-years satellite observations have shown ice shelves collapse, thin and retreat, however, there are few measurements of the Antarctic wide change in ice shelf area. Here, we use MODIS satellite data to measure the change in ice shelf calving front position and area on 34 ice shelves in Antarctica, from 2009 to 2019. Over the last decade, a reduction in area on the Antarctic Peninsula (6,692.5 km2) and West Antarctica (5,563.1 km2), has been outweighed by area growth in East Antarctica (3,532.1 km2) and the large Ross and Ronne-Filchner Ice Shelves (14,027.9 km2). The largest retreat was observed on Larsen-C Ice Shelf where 5,916.6 km2 of ice was lost during an individual calving event in 2017, and the largest area increase was observed on Ronne Ice Shelf in East Antarctica, where gradual advance over the past decade (535.3 km2/yr) led to a 5,888.6 km2 area gain from 2009–2019. Overall, the Antarctic Ice Shelf area has grown by 5,304.5 km2 since 2009, with 18 ice shelves retreating and 16 larger shelves growing in area. Our observations show that Antarctic Ice Shelves gained 660.6 Gt of ice mass over the decade whereas the steady state approach would estimate substantial ice loss over the same period, demonstrating the importance of using time-variable calving flux observations to measure change.

南极冰架（Antarctic Ice Shelves）对陆基冰盖具备拥托支撑作用，可稳定接地冰（grounded ice）的流动及其对全球海平面的贡献。过去50年间的卫星观测显示，冰架发生崩解、减薄与退缩，但针对全南极范围冰架面积变化的实测数据仍较为匮乏。本研究借助MODIS卫星数据，对2009至2019年间南极34处冰架的崩解前沿（calving front）位置与面积变化展开测算。近十年间，南极半岛的冰架面积减少6692.5 km²，西南极洲冰架面积减少5563.1 km²；而上述缩减规模被东南极洲（面积增长3532.1 km²）以及大型罗斯冰架（Ross Ice Shelf）、龙尼-菲尔希纳冰架（Ronne-Filchner Ice Shelf）的面积增长所抵消，后者累计增幅达14027.9 km²。最显著的冰架退缩事件发生于拉森-C冰架（Larsen-C Ice Shelf），该冰架在2017年的单次崩解事件中损失了5916.6 km²的冰体；而面积增幅最大的则为东南极洲的龙尼冰架（Ronne Ice Shelf），其在过去十年间以年均535.3 km²的速率缓慢推进，2009至2019年间累计面积增长达5888.6 km²。总体而言，自2009年以来，南极冰架总面积累计增加5304.5 km²，其中18处冰架出现退缩，16处大型冰架实现面积扩张。本次观测结果显示，南极冰架在十年间累计获得660.6亿吨冰量，而采用稳态方法估算的同期冰量损失则十分显著，这凸显了利用时变崩解通量（time-variable calving flux）观测开展变化测算的重要性。