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

• Main Authors: Poinar, Kristin, Joughin, Ian, Lenaerts, Jan T.M., Van Den Broeke, Michiel R.
• Other Authors: Sub Dynamics Meteorology, Marine and Atmospheric Research
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: cryo-hydrologic warming; Greenland ice sheet; ice dynamics; ice-sheet modelling; polar firn; Earth-Surface Processes; Greenland; Jakobshavn Isbræ; Ice Sheet; Jakobshavn; Jakobshavn isbræ
• Online Access: https://dspace.library.uu.nl/handle/1874/350702

Surface meltwater can refreeze within firn layers and crevasses to warm ice through latent-heat 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 Pâkitsoq (near Swiss Camp) and Jakobshavn Isbræ 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°C. By contrast, meltwater refreezing in crevasses (cryo-hydrologic warming) at depths of ~300 m warms the ice in Pâkitsoq by up to 10°C, but this causes minimal increase in ice motion (<10 m a-1). Pâkitsoq 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 ~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.