Antarctic high-resolution ice flow mapping and increased mass loss in Wilkes Land, East Antarctica during 2006–2015

Abstract. Substantial accelerated mass loss, extensive dynamic thinning on the periphery, and grounding line retreat in the Amundsen Sea Embayment, have amplified the long-standing concerns on the instability of the Antarctic ice sheet. However, the evolution of the ice sheet and the underlying causes of the changes remain poorly understood due in part to incomplete observations. Here, we constructed the ice flow maps for the years 2014 and 2015 at high resolution (100 m), inferred from Landsat 8 images using feature tracking method. These maps were assembled from 10,690 scenes of displacement vectors inferred from more than 10,000 optical images acquired from December 2013 to March 2016. We also estimated the mass discharges of the Antarctic ice sheet in 2006, 2014, and 2015 using the high-resolution ice flow maps, InSAR-derived ice flow map, and the ice thickness data. An increased mass discharge (40 ± 24 Gt yr⁻¹) from East Indian Ocean sector was found in the last decade, attributed to unexpected widespread accelerating glaciers in Wilkes Land, East Antarctica, while the other five oceanic sectors did not show any significant changes, contrary to the long-standing belief that present-day accelerated mass loss primarily originates from West Antarctica and Antarctic Peninsula. In addition, we compared the ice sheet mass discharge with the new surface mass balance (SMB) data to estimate the Antarctic mass balance. The most significant change of mass balance also occurred in East Indian Ocean during the last decade, reaching −40 ± 50 Gt yr⁻¹, the large uncertainty is caused mainly by error in the SMB data. The newly discovered significant accelerated mass loss and speedup of ice shelves in Wilkes Land suggest the potential risk of abrupt and irreversible destabilization, where the marine ice sheets on an inland-sloping bedrock, are adversely impacted by increasingly warmer temperature and warm ocean current intrusion, all of which may pose an unexpected threat of increased sea level rise.