The Role of Buoyancy in Controlling Glacier Caving

Calving is a prominent process removing mass from the Greenland Ice Sheet. Observations show that the calving fronts of Greenland glaciers are sometimes uplifted and sometimes slumped downward. We hypothesize that this is related to buoyancy forces promoting uplift as the calving front begins to float. To assess any spatial variations in calving front direction, we examined 30 Greenland Glacier altimetry profiles from Operation IceBridge and classified them based on the calving front shape. We examined multiple years for each glacier to account for any year to year variations in calving shape and then classified each profile to determine if it represented uplift, slumping or indeterminate. We found 60% of the glaciers displayed at least one year with a different classification than the other years and found no statistical relationship between calving shape and geographic location, geometric variables (i.e., retrograde of prograde slope). Statistical analyses suggested no indication of temporal influence as the likelihood for “up” and “down” calving fronts to occur in any given year was nearly equal. We hypothesize that the buoyantly uplifting profiles are related to the formation of a buoyant bulge beneath the water line that precedes calving whilst downward slumping profiles likely correspond to glaciers that have recently had a calving event.