Greenland outlet glacier ice - flow variability

1 I ce mass loss from the Greenland Ice Sheet is a primary contributor to global sea level rise. The rate of ice loss has accelerated over the last couple of decades and Greenland currently contributes about 0.7-1.1 mm/yr to sea-level rise (260-380 Gt/ice per year; Enderlin et al. 2014; Shepherd et al. 2012). Predicting the potential rate and limits of future mass loss requires a clear understanding of ice sheet dynamics and how the ice sheet is coupled to the climate system. Roughly a third to a half of Greenland ice loss is due to discharge through iceberg calving at the ice-ocean interface, as opposed to in situ surface melt (Enderlin et al. 2014; Shepherd et al. 2012). Glacier velocity, as well as ice thickness, terminus advance and retreat, and the mechanisms controlling their variability, must be understood to calculate and predict ice sheet discharge. Characterization and understanding of ice sheet velocity contributes both to exploring the processes controlling ice dynamics and to constraining ice sheet models used to predict future mass loss and associated sea-level rise.