Rapid basal melting of the Greenland Ice Sheet from surface meltwater drainage

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Young, Tun Jan, Christoffersen, Poul, Bougamont, Marion, Tulaczyk, Slawek M, Hubbard, Bryn, Mankoff, Kenneth D, Nicholls, Keith W, Stewart, Craig L
• Other Authors: University of St Andrews. School of Geography & Sustainable Development
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: Climate change; Radio echo sounding; Greenland; Glaciology; Ice sheets; GB Physical geography; GE Environmental Sciences; DAS; SDG 13 - Climate Action; MCC; GB; GE; glacier; greenlandic; Ice Sheet
• Online Access: http://hdl.handle.net/10023/27371; https://doi.org/10.1073/pnas.2116036119

Funding: This research was funded by the European Research Council under the European Union’s Horizon 2020 research and innovation program (Grant 683043). P.C., M.B., and B.H. were supported by the Natural Environment Research Council (Grants NE/K005871/1 and NE/K006126). B.H. was also supported by the Higher Education Funding Council for Wales and an Aberystwyth University Capital Equipment Grant. Subglacial hydrologic systems regulate ice sheet flow, causing acceleration or deceleration, depending on hydraulic efficiency and the rate at which surface meltwater is delivered to the bed. Because these systems are rarely observed, ice sheet basal drainage represents a poorly integrated and uncertain component of models used to predict sea level changes. Here, we report radar-derived basal melt rates and unexpectedly warm subglacial conditions beneath a large Greenlandic outlet glacier. The basal melt rates averaged 14 mm ⋅d-1 over 4 months, peaking at 57 mm ⋅d-1 when basal water temperature reached +0.88∘C in a nearby borehole. We attribute both observations to the conversion of potential energy of surface water to heat in the basal drainage system, which peaked during a period of rainfall and intense surface melting. Our findings reveal limitations in the theory of channel formation, and we show that viscous dissipation far surpasses other basal heat sources, even in a distributed, high-pressure system. Publisher PDF Peer reviewed