An empirical relationship between iceberg size and MCSF, a summary measure of glacial‐earthquake size, was recently demonstrated by Olsen and Nettles (2019). Though visual observation of large calving events is rare, ∼60 glacial earthquakes generated by these calving events are currently recorded each year by regional and global seismic stations. The number of gigaton‐sized iceberg‐calving events occurring annually at Greenland glaciers is increasing, part of a larger trend of accelerating mass loss from the Greenland Ice Sheet. As such, there is a pressing need for (1) improved, long-term observations at the ice-ocean and ice-bed boundaries, (2) more observationally constrained numerical ice flow models that are coupled to atmosphere and ocean models, and (3) continued development of a collaborative and interdisciplinary scientific community. These gaps impede our ability to understand past changes in dynamics and to make more accurate mass loss projections under future climate change. Although many processes are far better understood than they were even a decade ago, fundamental gaps in our understanding of certain processes remain. Here we review the progress in understanding GrIS outlet glacier sensitivity to climate change, how mass loss has changed over time, and how our understanding has evolved as observational capacity expanded. For example, recent (beginning in the late 1990s) mass loss via outlet glaciers has been attributed primarily to changing ice-ocean interactions, driven by both oceanic and atmospheric warming, but the exact mechanisms controlling the onset of glacier retreat and the processes that regulate the amount of retreat remain uncertain. Many of these processes change on a range of overlapping timescales and are challenging to observe, making them difficult to understand and thus missing in prognostic ice sheet/climate models. This is particularly true for outlet glaciers in Greenland that terminate in the ocean because their flow is strongly controlled by multiple processes that alter their boundary conditions at the ice-atmosphere, ice-ocean, and ice-bed interfaces. Uncertainty in GrIS mass loss projections in part stems from the nonlinear response of the ice sheet to climate forcing, with many processes at play that influence how mass is lost. Unfortunately, despite the rapid growth of interest in GrIS mass loss and its impacts, we still lack the ability to confidently predict the rate of future mass loss and the full impacts of this mass loss on the globe. Observations also indicate that the impact of a melting GrIS extends beyond sea-level rise, including changes to ocean properties and circulation, nutrient and sediment cycling, and ecosystem function. Mass loss from the Greenland ice sheet (GrIS) has increased over the last two decades in response to changes in global climate, motivating the scientific community to question how the GrIS will contribute to sea-level rise on timescales that are relevant to coastal communities. We suggest that this buoyancy-driven mechanism for calving may be common elsewhere in Greenland and could be a first-order control on the ice sheet's future contribution to sea-level rise. We find that during these two summers dynamic mass loss at Helheim Glacier was dominated by calving events exceeding 1 km(3) that were the result of buoyant flexure and the propagation of basal crevasses. Our digital elevation models are derived from stereo terrestrial photography taken over the summers of 20. Here we present a record of daily digital elevation models from the calving margin of Greenland's Helheim Glacier at a high spatial resolution. However, present physical models remain a coarse approximation of real calving mechanisms because models are poorly constrained by sparse glacier geometry observations(5). The largest contributions from the main outlet glaciers of the Greenland ice sheet to sea-level rise over the next two centuries have been projected to be dynamic in origin, that is, driven by glacier flow and calving(4). Iceberg calving accounts for a significant proportion of annual mass loss from marine-terminating glaciers(1,2) and may have been a factor in the rapid demise of ancient ice sheets(3).
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