Duration and ice thickness of a Late Holocene outlet glacier advance near Narsarsuaq, southern Greenland
<p>Greenland Ice Sheet (GrIS) outlet glaciers are currently losing mass, leading to sea level rise. Reconstructions of past outlet glacier behavior through the Holocene help us better understand how they respond to climate change. Kiattuut Sermiat, a southern Greenland outlet glacier near Nars...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-09-01
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| Series: | Climate of the Past |
| Online Access: | https://cp.copernicus.org/articles/19/1777/2023/cp-19-1777-2023.pdf |
| _version_ | 1797690079697698816 |
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| author | P. J. K. Puleo Y. Axford |
| author_facet | P. J. K. Puleo Y. Axford |
| author_sort | P. J. K. Puleo |
| collection | DOAJ |
| description | <p>Greenland Ice Sheet (GrIS) outlet glaciers are currently losing mass, leading to sea level rise. Reconstructions of past outlet glacier behavior through the Holocene help us better understand how they respond to climate change. Kiattuut Sermiat, a southern Greenland outlet glacier near Narsarsuaq, is known to have experienced an unusually large Late Holocene
advance that culminated at <span class="inline-formula">∼1600</span> cal yr BP and exceeded the
glacier's Little Ice Age extent. We report sedimentary records from two
lakes at slightly different elevations in an upland valley adjacent to
Kiattuut Sermiat. These reveal when the outlet glacier's surface elevation
was higher than during the Little Ice Age and constrain the associated
outlet glacier surface elevation. We use bulk sediment geochemistry,
magnetic susceptibility, color, texture, and the presence of aquatic plant
macrofossils to distinguish between till, glaciolacustrine sediments, and
organic lake sediments. Our <span class="inline-formula"><sup>14</sup></span>C results above basal till recording
regional deglaciation skew slightly old due to a reservoir effect but are
generally consistent with regional deglaciation occurring <span class="inline-formula">∼</span> 11 000 cal yr BP. Neoglacial advance of Kiattuut Sermiat is recorded by deposition of glaciolacustrine sediments in the lower-elevation lake, which we infer was subsumed by an ice-dammed lake that formed along the glacier's margin just after <span class="inline-formula">∼</span> 3900 cal yr BP. This timing is consistent with several other glacial records in Greenland showing neoglacial cooling driving advance between <span class="inline-formula">∼</span> 4500–3000 cal yr BP. Given that glaciolacustrine sediments were deposited only in the lower-elevation lake, combined with glacial geomorphological evidence in the valley containing these lakes, we estimate the former ice margin's elevation to have been <span class="inline-formula">∼</span> 670 m a.s.l., compared with <span class="inline-formula">∼</span> 420 m a.s.l. today. The ice-dammed lake persisted until the glacier surface fell below this elevation at <span class="inline-formula">∼</span> 1600 cal yr BP. The retreat timing contrasts with overall evidence for cooling and glacier advance in the region at that time, so we infer that Kiattuut Sermiat's retreat may have resulted from reduced snowfall amounts and/or local glaciological complexity. High sensitivity to precipitation changes could also explain the relatively limited Little Ice Age advance of Kiattuut Sermiat compared with the earlier neoglacial advance.</p> |
| first_indexed | 2024-03-12T01:54:22Z |
| format | Article |
| id | doaj.art-8eb7621dcd754f2f858a75d9a1d1148f |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-03-12T01:54:22Z |
| publishDate | 2023-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-8eb7621dcd754f2f858a75d9a1d1148f2023-09-08T06:53:15ZengCopernicus PublicationsClimate of the Past1814-93241814-93322023-09-01191777179110.5194/cp-19-1777-2023Duration and ice thickness of a Late Holocene outlet glacier advance near Narsarsuaq, southern GreenlandP. J. K. PuleoY. Axford<p>Greenland Ice Sheet (GrIS) outlet glaciers are currently losing mass, leading to sea level rise. Reconstructions of past outlet glacier behavior through the Holocene help us better understand how they respond to climate change. Kiattuut Sermiat, a southern Greenland outlet glacier near Narsarsuaq, is known to have experienced an unusually large Late Holocene advance that culminated at <span class="inline-formula">∼1600</span> cal yr BP and exceeded the glacier's Little Ice Age extent. We report sedimentary records from two lakes at slightly different elevations in an upland valley adjacent to Kiattuut Sermiat. These reveal when the outlet glacier's surface elevation was higher than during the Little Ice Age and constrain the associated outlet glacier surface elevation. We use bulk sediment geochemistry, magnetic susceptibility, color, texture, and the presence of aquatic plant macrofossils to distinguish between till, glaciolacustrine sediments, and organic lake sediments. Our <span class="inline-formula"><sup>14</sup></span>C results above basal till recording regional deglaciation skew slightly old due to a reservoir effect but are generally consistent with regional deglaciation occurring <span class="inline-formula">∼</span> 11 000 cal yr BP. Neoglacial advance of Kiattuut Sermiat is recorded by deposition of glaciolacustrine sediments in the lower-elevation lake, which we infer was subsumed by an ice-dammed lake that formed along the glacier's margin just after <span class="inline-formula">∼</span> 3900 cal yr BP. This timing is consistent with several other glacial records in Greenland showing neoglacial cooling driving advance between <span class="inline-formula">∼</span> 4500–3000 cal yr BP. Given that glaciolacustrine sediments were deposited only in the lower-elevation lake, combined with glacial geomorphological evidence in the valley containing these lakes, we estimate the former ice margin's elevation to have been <span class="inline-formula">∼</span> 670 m a.s.l., compared with <span class="inline-formula">∼</span> 420 m a.s.l. today. The ice-dammed lake persisted until the glacier surface fell below this elevation at <span class="inline-formula">∼</span> 1600 cal yr BP. The retreat timing contrasts with overall evidence for cooling and glacier advance in the region at that time, so we infer that Kiattuut Sermiat's retreat may have resulted from reduced snowfall amounts and/or local glaciological complexity. High sensitivity to precipitation changes could also explain the relatively limited Little Ice Age advance of Kiattuut Sermiat compared with the earlier neoglacial advance.</p>https://cp.copernicus.org/articles/19/1777/2023/cp-19-1777-2023.pdf |
| spellingShingle | P. J. K. Puleo Y. Axford Duration and ice thickness of a Late Holocene outlet glacier advance near Narsarsuaq, southern Greenland Climate of the Past |
| title | Duration and ice thickness of a Late Holocene outlet glacier advance near Narsarsuaq, southern Greenland |
| title_full | Duration and ice thickness of a Late Holocene outlet glacier advance near Narsarsuaq, southern Greenland |
| title_fullStr | Duration and ice thickness of a Late Holocene outlet glacier advance near Narsarsuaq, southern Greenland |
| title_full_unstemmed | Duration and ice thickness of a Late Holocene outlet glacier advance near Narsarsuaq, southern Greenland |
| title_short | Duration and ice thickness of a Late Holocene outlet glacier advance near Narsarsuaq, southern Greenland |
| title_sort | duration and ice thickness of a late holocene outlet glacier advance near narsarsuaq southern greenland |
| url | https://cp.copernicus.org/articles/19/1777/2023/cp-19-1777-2023.pdf |
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