Rapid basal melting of the Greenland Ice Sheet from surface meltwater drainage
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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.
Young , T J , Christoffersen , P , Bougamont , M , Tulaczyk , S M , Hubbard , B , Mankoff , K D , Nicholls , K W & Stewart , C L 2022 , ' Rapid basal melting of the Greenland Ice Sheet from surface meltwater drainage ' , Proceedings of the National Academy of Sciences of the United States of America , vol. 119 , no. 10 , e2116036119 . https://doi.org/10.1073/pnas.2116036119
Proceedings of the National Academy of Sciences of the United States of America
Copyright © 2022 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY).
DescriptionFunding: 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.
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