Bowdoin Glacier

Context

The observed rapid retreat of ocean-terminating glaciers in southern Greenland in the last two decades has now propagated to the northwest. Hence, tidewater glaciers in this area, some of which have remain stable for decades, have started retreating rapidly through iceberg calving in recent years, thus allowing a monitoring and investigation of ice dynamical changes starting from the early stages of retreat.

Bowdoin Glacier, a tidewater outlet glacier located at the north-western margin of the Greenland Ice Sheet experiences surface lowering at a rate of 1.5 m/a since 2007. A rapid calving front retreat of 260 m/a was also observed since 2008, while no significant changes occurred during the previous 20 years. From July 2014 to July 2015, we monitored, 2 km upstream from the calving front, subglacial water pressure changes in boreholes, internal ice deformation through tilt sensors at different depths, englacial ice temperature profiles from the glacier bed to the surface, and high resolution surface motion from GPS records.

Animations

Summer snow melt, iceberg calving and sea ice breakoff in Bowdoin fjord. Contains modified Copernicus Sentinel data (2016). Processed with Sentinelflow.

These measurements show that the glacier is temperate-based, yet internal deformation accounts for about 10 % of the annual surface motion. A seasonal increase in both deformation and sliding at the onset of the melt season is associated with a drop in water pressure in part of the subglacial system.

One year of ice deformation at Bowdoin Glacier.