Interaction between subsurface ocean waters and calving of Jakobshavn Isbræ during the Late Holocene

Andresen, C.; McCarthy, D.; Dylmer, C.; Seidenkrantz, M-S.; Kuijpers, A.; Lloyd, J.

Abstract

A marine sediment core from Vaigat in Disko Bugt, West Greenland, has been analysed in terms of lithology, dinoflagellate cysts and foraminifera in order to evaluate the influence of oceanographic variability on West Greenland glacier stability. The data show that during the past 5200 years the Atlantic foraminiferal abundance in the subsurface waters of the West Greenland Current (WGC) episodically increased, indicating periods of increases in the inflow of subsurface warm Atlantic water at 2000—1500 cal. yr BP and 1300 cal. yr BP as well as periods of less pronounced increased bottom-water temperatures around 4700—4000 cal. yr BP, 3100—2800, 2600, 1000—800, 500—400, and at 200 cal. yr. The sedimentological and dinoflagellate cyst data indicate that these episodes with enhanced advection of Irminger Sea-derived waters are accompanied by increased iceberg rafting, which we link to increased iceberg calving in relation to destabilization of the Jakobshavn Isbrae. The long-term trend in the data documents the end of a late-Holocene Thermal Maximum between 5200 and 4300 cal. yr BP and a final onset of the Neoglaciation at 3500 cal. yr BP. Increased responses of the iceberg rafting after 3500 cal. yr BP, reflects a westward/seaward advance of the glacier margin in relation to onset of Neoglaciation and a development of the glacier into a floating tongue after 2000 cal. yr BP. A comparison of our record with a record from the eastern North Atlantic indicates that a NAO-like anomaly pattern between subsurface waters in West Greenland and atmospheric temperature in the Eastern North Atlantic may have been operating during most of the late Holocene. However, during the past 1000 years the NAO signal may have weakened as some other mode of climate variability overprints the anti-phase climate signal in this region.

Citation

Andresen, C., McCarthy, D., Dylmer, C., Seidenkrantz, M., Kuijpers, A., & Lloyd, J. (2011). Interaction between subsurface ocean waters and calving of Jakobshavn Isbræ during the Late Holocene. Holocene, 21(2), 211-224. https://doi.org/10.1177/0959683610378877

• Journal Article Type: Article
• Publication Date: Mar 1, 2011
• Deposit Date: Aug 25, 2011
• Publicly Available Date: Aug 16, 2013
• Journal: Holocene
• Print ISSN: 0959-6836
• Electronic ISSN: 1477-0911
• Publisher: SAGE Publications
• Peer Reviewed: Peer Reviewed
• Volume: 21
• Issue: 2
• Pages: 211-224
• DOI: https://doi.org/10.1177/0959683610378877
• Keywords: Dinoflagellate, Foraminifera, Iceberg calving, Jakobshavn Isbrae, Late-Holocene climate variability, West Greenland Current
• Public URL: https://durham-repository.worktribe.com/output/1537313