Englacial latent-heat transfer has limited influence on seaward ice flux in western Greenland

Surface meltwater can refreeze within firn layers and crevasses to warm ice through laten-theat transfer on decadal to millennial timescales. Earlier work posited that the consequent softening of the ice might accelerate ice flow, potentially increasing ice-sheet mass loss. Here, we calculate the effect of meltwater refreezing on ice temperature and softness in the P (a) over cap ktsoq (near Swiss Camp) and Jakobshavn Isbr ae regions of western Greenland using a numeric model and existing borehole measurements. We show that in the Jakobshavn catchment, meltwater percolation within the firn warms the ice at depth by 3-5 degrees C. By contrast, meltwater refreezing in crevasses (cryo-hydrologic warming) at depths of similar to 300 m warms the ice in P (a) over cap kitsoq by up to 10 degrees C, but this causes minimal increase in ice motion (< 10 ma(-1)). P<(a)over cap>kitsoq is representative of western Greenland's land-terminating ice, where the slow movement of ice through a wide ablation zone provides ideal conditions for cryo-hydrologic warming to occur. We find that only similar to 37% of the western Greenland ice flux, however, travels through such areas. Overall, our findings suggest that cryo-hydrologic warming will likely have only a limited effect on the dynamic evolution of the Greenland ice sheet.