Satellite-based assessment of Getz Ice Shelf extent changes in the Amundsen Sea sector

Antarctic Ice Shelves continuously modifies land ice and ocean boundaries and influences global climate change and sea-level fluctuations. The Getz Ice Shelf (GIS), which fringes nearly half of the West Antarctic coastline in the Amundsen Sea sector, experiences substantial basal melting. This study presents a long-term, satellite-based assessment of morphological changes in the GIS using multi-temporal austral summer (January–March) observations spanning 22-years (2003–2022). To capture spatial variability, the ice shelf was divided into three sectors (I–III) based on physiographic setting and dominant oceanographic processes, and changes in ice shelf extent were quantified along uniformly spaced transects at 5 km intervals The average of rates, end point rate, and linear regression method were employed to estimate the rate of change, with the linear regression showing the strongest correlation. Past ice shelf extents were reconstructed, and predicted ice shelf positions for the next 5 and 10 years and cross-validated with correlation coefficient and root-mean-square error. The result reveals a mean recession rate of -41.6 m/year during the austral summer of 2003–2022, and about 70% of transects show recession, while only 30% of transects are associated with progradation. LR-based projections indicate progradation in Sector I and continued recession in Sectors II and III, with pronounced retreat in Sector III between Wright Island and Martin Peninsula (~2.1 km by 2027 and ~2.5 km by 2032). Approximately 45% of transects in Sectors II and III have RMSE values of ±200 m, indicating good agreement between the estimated and satellite-based ice-shelf positions. Observed changes are linked to large-scale climate forcing, including variations in wind speed, sea surface temperature, and the Southern Annular Mode (SAM). Positive SAM and increased zonal winds may cause warm water upwelling near the Antarctic coast, impacting the extent. Changes in sea ice mass and accelerated basal melting are largely caused by ocean warming and geomorphological features, viz., bays, inlets, and islands. The study emphasizes the significant impact of ocean-atmospheric factors on Antarctic ice shelf dynamics and highlights the necessity for ongoing satellite observations and enhanced comprehension of these processes to accurately predict future changes in Antarctic ice shelves.

Keywords:

Getz Ice Shelf; West Antarctica; glacier monitoring; remote sensing; MODIS; ice shelf retreat; transect analysis; atmosphere-ocean forcings; future predictions.