CPP-07. Characteristics and Changes of the Hunt Fjord Ice Shelf, Northern Greenland

Abstract
The Arctic is undergoing intense regional warming. As a result, Arctic ice shelves have declined in area precipitously over the past several decades. Here we use a special collection of off-nadir Landsat 8 and Moderate-resolution Imaging Spectroradiometer (MODIS) imagery, Ice, Cloud, and land Elevation Satellite (ICESat) and ICESat-2 data, a 1978 photomosaic and photogrammetric-derived digital elevation model (DEM), and the ArcticDEM to track the recent evolution of a relatively understudied Arctic ice shelf in northernmost Greenland, the Hunt Fjord Ice Shelf (HFIS). There are several distinct provenance regions, consisting of floating glacier tongues and several multi-decadal fast ice areas with a variety of decameter-scale corrugations (like many Arctic ice shelves). Satellite images show little change in HFIS between 1978 and 2012, followed by mid-summer calvings during several events (2012, 2016, and 2019) resulting in a total area reduction of 42.5 km2 (~57%). Thickness of the shelf appears to be 5 to 64 meters and has thinned since 1978. Shelf area losses began as the number of surface melt days on the adjacent Greenland ice sheet more than doubled relative to the 1980s. Ice shelf calvings occur during open-water periods at the ice shelf front; however, low sea ice concentrations offshore of HFIS prior to 2012 did not lead to any calving events. Tributary glaciers in HFIS fjord have almost doubled in velocity since the 1980s and they have thinned by 3 to 20 m near their grounding zones, likely due to increased contact with warm Atlantic Water below the polar water layer in the fjord. As the Arctic continues to warm and surface melting increases, we anticipate further break-up of HFIS and retreat of its tributaries in this decade.