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Woodroffe, Sarah, Wake, Leanne, Barlow, Natasha, Kjelsen, Kristian, Best, Louise 
ORCID: 0000-0003-3731-054X and Sefton, Juliet
(2019)
Saltmarsh records of post Little Ice Age mass balance changes in Greenland.
In: XX INQUA Congress 2019, 25-31 July 2019, Dublin, Ireland.
(Unpublished)
Abstract
Saltmarshes provide excellent archives of relative sea-level (RSL) changes over a range of different timescales. In Greenland they yield precise RSL data over the past few decades to hundreds of years that can help constrain Greenland Ice Sheet mass changes during and after the Little Ice Age (LIA). They are particularly valuable as they provide a longer term context upon which to evaluate recent tide gauge and GPS records which span only the past decade or so. In Southeast Greenland the current rate of crustal uplift recorded by GPS is approximately +7 mm/yr at the open coast and up to +18 mm/yr close to the ice sheet margin. At Ilulissat Isfjord on the west coast uplift rates are similarly 7.9 mm/yr at the open coast and 18.8 mm/yr at the head of the isfjord. These rapid crustal uplift rates reflect high rates of recent mass loss in west and southeast Greenland. This study investigates fossil saltmarshes located within 5 km of the ice sheet margin at the head of Skjoldungen fjord in southeast Greenland, and just south of Ilulissat isfjord in west Greenland. The aim in both locations is to use RSL data to establish the timing and magnitude of mass loss since the end of the LIA. This is the first time that saltmarshes so close to the ice sheet margin, and close to the globally important Jakobshavn Isbrae ice stream have been utilised to create high precision proxy-GPS data for the last few hundred years. Microfossil (diatom) evidence from saltmarsh sediments at the southeast site record a recent change from RSL rise to stable RSL, then RSL fall during the past 200 years. We interpret the change from RSL rise to stable RSL as evidence for the initial onset of mass loss locally from the Greenland Ice Sheet at the end of the Little Ice Age. Later RSL fall occurs as mass loss accelerates during the 20th Century. A similar pattern is seen in the west but with RSL rise interrupted by RSL fall caused by post-LIA mass loss, and changes in the rate of RSL change coincide with fluctuations in the frontal position of Jakobshavn Isbrae over the last few hundred years. This study provides the first direct evidence that saltmarsh sediments from near-field sites can be used to reconstruct the timing of recent mass loss change from ice streams and other marginal areas of the Greenland Ice Sheet, extending direct GPS observations back to the end of the Little Ice Age and beyond using geological data.
| Item Type: | Conference or Workshop Item (Lecture) |
|---|---|
| Subjects: | G Geography. Anthropology. Recreation > G Geography (General) G Geography. Anthropology. Recreation > GB Physical geography G Geography. Anthropology. Recreation > GE Environmental Sciences |
| Divisions: | Schools and Research Institutes > School of Education and Science |
| Depositing User: | Louise Best |
| Date Deposited: | 06 Sep 2024 13:44 |
| Last Modified: | 06 Sep 2024 13:44 |
| URI: | https://eprints.glos.ac.uk/id/eprint/14353 |
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