An updated glacier inventory of the Svalbard Archipelago from 2021 based on Sentinel-2 imagery

This study presents a new glacier inventory for the Svalbard Archipelago, derived from cloud-free Sentinel-2 satellite imagery acquired in late summer 2021. Using a semi-automated mapping approach followed by manual correction, 1693 glaciers larger than 0.01 km 2 were delineated and characterized by geometric and topographic attributes. The glacier outline uncertainty was calculated by independent digitizing of 17 glaciers by four analysts. The total glacierized area was found to be 32,518 ± 344 km 2 , covering approximately 52% of the archipelago. Compared to previous inventories, the glacierized area has decreased by 1257 km 2 over the past two decades, with an average annual loss of 97 km 2 a -1 (-0.3% per year of recession rate), and a total reduction of 20% since 1936 (based on a subsample dataset). The analysis also identified 24 advancing glaciers between the 2000s and 2021, 21 of which are previously documented surge-type glaciers, reinforcing the classification of Svalbard as a surge glacier hotspot. In this context, four glaciers showed signs of advance without prior surge records, suggesting potential new surge activity. These results highlight the importance of frequent glacier monitoring in the Arctic, a region undergoing rapid change due to climate and oceanic forcings and offers a valuable foundation for future modelling of glacier dynamics and sea-level contributions in a rapidly warming Arctic.