Calving front dynamics in coastal Dronning Maud Land, East Antarctica

Antarctica’s ice shelves play a crucial role in the stability of the ice sheet and the rate at which it contributes to sea-level rise. While large, tabular iceberg calving accounts for most of the ice discharged from Antarctic ice shelves, less attention has been given to smaller-scale frontal ablation processes that also contribute to ice-shelf area and mass changes. This can be caused by: (1) the collision of large- to medium-sized (>100 km²) tabular icebergs with the coastline, (2) undercutting of ice-shelf fronts by ocean waves, causing edge wasting, and (3) the absence of protective landfast sea ice that can expose calving fronts to damaging ocean swell.

Here, we analyse calving front dynamics and frontal ablation through observed ice-shelf advance and retreat rates in the coastal Dronning Maud Land region of East Antarctica since 2015. Using time series derived from semi-automated classification of Sentinel-1 radar imagery, we quantify ice-shelf frontal ablation and mass change rates. Our results reveal complex seasonal and interannual patterns in calving front dynamics, demonstrating the importance of multiple ice-shelf frontal ablation processes. Iceberg collisions triggered a cascade of regional calving in 2021, as well as damage to several fronts that did not calve. These cascading calving events were initiated by collisions with iceberg D28 from the Amery Ice Shelf, which released further icebergs that drifted and collided with other parts of the coast. Observations of small-scale ice-shelf frontal retreat during periods of unusually absent landfast sea ice and dense pack ice suggests frontal ablation is partially linked to the persistence of protective sea ice. Altogether, these findings provide improved knowledge of calving front dynamics and its drivers in East Antarctica, needed for refining calving parameterizations to more accurately predict ice-shelf evolution and stability.