Modelling ice-sheet dynamics in response to climate changes in southern Iceland

• Main Authors: Bingham, RG, Hulton, NRJ, Dugmore, AJ
• Format: Other Non-Article Part of Journal/Newspaper
• Language: English
• Published: 2000
• Subjects: Ela; Eyjafjallajokull; Patagonia; Ice Sheet; Iceland
• Online Access: http://hdl.handle.net/1983/c5c06a77-1df9-4951-9015-147621032b9e; https://research-information.bris.ac.uk/en/publications/c5c06a77-1df9-4951-9015-147621032b9e

A three-dimensional, time-dependent numerical model for polar ice-sheets was used heuristically to investigate changing patterns of ice-sheet dynamics in southern Iceland in response to climatic forcing. The model has been used previously to investigate ice-sheet dynamics in Patagonia and nothern Europe. Ice development over southern Iceland is forced using a linear relationship between mass balance and altitude based on observations over Solheimajokull, a southern outlet of Myrdalsjokull. The model uses a 1km x 1km DEM of southern Iceland derived from ETOPO-5 with subglacial topography incorporated for Myrdalsjokull from published data in Dugmore and Sugden (1991). A continentality factor is introduced which raises inland ELAs and also slackens the mass balance-altitude gradient driving the model in these locations. Only by including these factors can the present-day ice distribution be adequately modelled, with the important assumption that ice in southern Iceland is currently in equilibrium. Growth from ice free to present conditions takes 10ka. The sensitivity of ice extents to ELA change in this region was investigated and shown to be typically non-linear. Further experiments were used to test the hypotheses of the existence of glacial refugium between Myrdalsjokull-Eyjafjallajokull during the Last Glacial Maximum (LGM). The model suggests that an ELA lowering of 500m, consistent with a ~5C temperature depression for southern Iceland at the LGM, is needed for ice to reach the coast. Such conditions would overrun any tentative refugia. The model was used to investigate the ELA raising consistent with widespread ice retreat from southern Iceland. The model suggests that an ELA rise of only 100m would be enough to obliterate almost completely ice from Myrdalsjokull, although it would be necessary for equilibrium to be reached. This conclusion implies that global warming could have serious consequences for ice distributions throughout Iceland in the relatively near future. A three-dimensional, time-dependent numerical model for polar ice-sheets was used heuristically to investigate changing patterns of ice-sheet dynamics in southern Iceland in response to climatic forcing. The model has been used previously to investigate ice-sheet dynamics in Patagonia and nothern Europe. Ice development over southern Iceland is forced using a linear relationship between mass balance and altitude based on observations over Solheimajokull, a southern outlet of Myrdalsjokull. The model uses a 1km x 1km DEM of southern Iceland derived from ETOPO-5 with subglacial topography incorporated for Myrdalsjokull from published data in Dugmore and Sugden (1991). A continentality factor is introduced which raises inland ELAs and also slackens the mass balance-altitude gradient driving the model in these locations. Only by including these factors can the present-day ice distribution be adequately modelled, with the important assumption that ice in southern Iceland is currently in equilibrium. Growth from ice free to present conditions takes 10ka. The sensitivity of ice extents to ELA change in this region was investigated and shown to be typically non-linear. Further experiments were used to test the hypotheses of the existence of glacial refugium between Myrdalsjokull-Eyjafjallajokull during the Last Glacial Maximum (LGM). The model suggests that an ELA lowering of 500m, consistent with a ~5C temperature depression for southern Iceland at the LGM, is needed for ice to reach the coast. Such conditions would overrun any tentative refugia. The model was used to investigate the ELA raising consistent with widespread ice retreat from southern Iceland. The model suggests that an ELA rise of only 100m would be enough to obliterate almost completely ice from Myrdalsjokull, although it would be necessary for equilibrium to be reached. This conclusion implies that global warming could have serious consequences for ice distributions throughout Iceland in the relatively near future.