Tidewater-glacier response to supraglacial lake drainage

• Published in: Nature Communications
• Main Authors: Stevens, L, Nettles, M, Davis, JL, Creyts, TT, Kingslake, J, Hewitt, I, Stubblefield, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Nature 2022
• Subjects: Greenland; glacier; Ice Sheet; Tidewater
• Online Access: https://doi.org/10.1038/s41467-022-33763-2; https://ora.ox.ac.uk/objects/uuid:a94e5b53-342c-4c6a-b090-87902ac22224

The flow speed of the Greenland Ice Sheet changes dramatically in inland regions when surface meltwater drains to the bed. But ice-sheet discharge to the ocean is dominated by fast-flowing outlet glaciers, where the effect of increasing surface melt on annual discharge is unknown. Observations of a supraglacial lake drainage at Helheim Glacier, and a consequent velocity pulse propagating down-glacier, provide a natural experiment for assessing the impact of changes in injected meltwater, and allow us to interrogate the subglacial hydrological system. We find a highly efficient subglacial drainage system, such that summertime lake drainage has little net effect on ice discharge. Our results question the validity of common remote-sensing approaches for inferring subglacial conditions, knowledge of which is needed for improved projections of sea-level rise.