Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates
<p>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 <span class="inline-formula">∼&l...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2024-03-01
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| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/18/1467/2024/tc-18-1467-2024.pdf |
| _version_ | 1797236862188781568 |
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| author | G. J. G. Paxman S. S. R. Jamieson A. M. Dolan M. J. Bentley |
| author_facet | G. J. G. Paxman S. S. R. Jamieson A. M. Dolan M. J. Bentley |
| author_sort | G. J. G. Paxman |
| collection | DOAJ |
| description | <p>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 <span class="inline-formula">∼</span> 79 % of Greenland and <span class="inline-formula">∼</span> 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 <span class="inline-formula">+</span>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.</p> |
| first_indexed | 2024-04-24T17:10:35Z |
| format | Article |
| id | doaj.art-753c2e16a13246f7ad1dc99329129a32 |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-04-24T17:10:35Z |
| publishDate | 2024-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-753c2e16a13246f7ad1dc99329129a322024-03-28T12:59:11ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242024-03-01181467149310.5194/tc-18-1467-2024Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climatesG. J. G. Paxman0S. S. R. Jamieson1A. M. Dolan2M. J. Bentley3Department of Geography, Durham University, Durham, DH1 3LE, United KingdomDepartment of Geography, Durham University, Durham, DH1 3LE, United KingdomSchool of Earth and Environment, University of Leeds, Leeds, LS2 9JT, United KingdomDepartment of Geography, Durham University, Durham, DH1 3LE, United Kingdom<p>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 <span class="inline-formula">∼</span> 79 % of Greenland and <span class="inline-formula">∼</span> 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 <span class="inline-formula">+</span>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.</p>https://tc.copernicus.org/articles/18/1467/2024/tc-18-1467-2024.pdf |
| spellingShingle | G. J. G. Paxman S. S. R. Jamieson A. M. Dolan M. J. Bentley Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates The Cryosphere |
| title | Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates |
| title_full | Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates |
| title_fullStr | Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates |
| title_full_unstemmed | Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates |
| title_short | Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates |
| title_sort | subglacial valleys preserved in the highlands of south and east greenland record restricted ice extent during past warmer climates |
| url | https://tc.copernicus.org/articles/18/1467/2024/tc-18-1467-2024.pdf |
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