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Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates

Paxman, Guy J. G.; Jamieson, Stewart S. R.; Dolan, Aisling M.; Bentley, Michael J.

Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates Thumbnail


Authors

Aisling M. Dolan



Abstract

The Greenland Ice Sheet is a key contributor to contemporary global sea level rise, but its long-term history and response to episodes of warming in Earth's geological past remain uncertain. The terrain covered by the ice sheet comprises ∼ 79 % of Greenland and ∼ 1.1 % of the Earth's land surface and contains geomorphological records that may provide valuable insights into past ice-sheet behaviour. Here we use ice surface morphology and radio-echo sounding data to identify ice-covered valleys within the highlands of southern and eastern Greenland and use numerical ice-sheet modelling to constrain the climatological and glaciological conditions responsible for valley incision. Our mapping reveals intricate subglacial valley networks with morphologies that are indicative of substantial glacial modification of an inherited fluvial landscape, yet many of these valleys are presently situated beneath cold-based, slow-moving (i.e. non-erosive) ice. We use the morphology of the valleys and our simple ice-sheet model experiments to infer that incision likely occurred beneath erosive mountain valley glaciers during one or more phases of Greenland's glacial history when ice was restricted to the southern and eastern highlands and when Greenland's contribution to barystatic sea level was up to +7 m relative to today. We infer that this valley incision primarily occurred prior to the growth of a continental-scale ice sheet, most likely during the late Miocene (ca. 7–5 Ma) and/or late Pliocene (ca. 3.6–2.6 Ma). Our findings therefore provide new data-based constraints on early Greenland Ice Sheet extent and dynamics that can serve as valuable boundary conditions in models of regional and global palaeoclimate during past warm periods that are important analogues for climate change in the 21st century and beyond.

Citation

Paxman, G. J. G., Jamieson, S. S. R., Dolan, A. M., & Bentley, M. J. (2024). Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates. The Cryosphere, 18(3), 1467-1493. https://doi.org/10.5194/tc-18-1467-2024

Journal Article Type Article
Acceptance Date Feb 13, 2024
Online Publication Date Mar 28, 2024
Publication Date Mar 4, 2024
Deposit Date Feb 20, 2024
Publicly Available Date Apr 22, 2024
Journal The Cryosphere
Publisher Copernicus Publications
Peer Reviewed Peer Reviewed
Volume 18
Issue 3
Pages 1467-1493
DOI https://doi.org/10.5194/tc-18-1467-2024
Public URL https://durham-repository.worktribe.com/output/2270256

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