Autumn Inflow of Atlantic Water Drives Seasonal Retreat of Glacier Fronts on the Northern Barents Sea Margin of Svalbard

During the 2010s, marine-terminating glaciers on the Barents Sea margin of the Svalbard archipelago lost considerable mass after many decades of stability. This change was preceded by the onset of a period of rapid warming of both the ocean and atmosphere in the northern Barents Sea. In this study, we investigate the sensitivity of glacier front positions to changes in the physical environment by examining the seasonal evolution of terminus retreat rates and their potential drivers in the ocean and the atmosphere. For the analysis, we compared satellite-derived weekly retreat rates of glacier termini along Nordaustlandet, Svalbard, with other environmental parameters including subsurface ocean temperature from a mooring located >30 km offshore. Along large parts of the glaciated coast, marine-terminating glaciers with deep grounding lines consistently experienced a seasonal retreat-advance cycle. Retreat was greatest in late autumn, suggesting that atmospheric forcing was not the main driver. Instead, the annual retreat coincided with the seasonal inflow of Atlantic Water into the northern Barents Sea, originating from the warm boundary current that runs along the continental slope of the Arctic Ocean. These results suggest that rates of terminus ablation in the study region respond rapidly and significantly to variations in subsurface ocean temperature offshore. This is consistent with simple, idealized experiments using a one-dimensional plume model, which show that the observed range of ocean temperatures may correspond to large variations in submarine melt rates at the glacier front. In a broader context, the study demonstrates the sensitivity and interconnectivity of components of the Arctic physical environment and implies that increased glacier mass loss is a possible effect of ocean Atlantification of the northern Barents Sea.