The role of ocean dynamics and meltwater input on the fate of Ellesmere’s ice shelves, glacier tongues and epishelf lakes
Investigators: A. Hamilton, D. Mueller, B. Laval
The project will evaluate ice-ocean dynamics of the Milne Fjord ice shelf and epishelf lake system on the northern coast of Ellesmere Island, Nunavut. Despite the existence of ice shelves in this region for the majority of the past 3000 to 5500 years (1-2) recent atmospheric warming has contributed to collapse of the remaining ice shelves and the loss of ice-shelf dammed lakes (epishelf lakes) (3-5). These studies have primarily addressed surface processes as the causal factors for ice shelf breakup, but changes in ocean stratification, meltwater flux, and subglacial thermodynamics may strongly influence the integrity and fate of these system. Despite the growing evidence of the importance of oceanic processes on tidewater glacier mass balance in Greenland (6-7) these processes remain poorly studied on related systems in the Canadian Arctic Archipelago (CAA). In addition, the recent sharp increase in mass loss from the glaciers and ice caps of the CAA, primarily in the form of meltwater runoff (8) suggest understanding the aquatic and oceanic factors contributing to ice shelf integrity and epishelf lake formation is critical.
Milne Fjord is the site of the only remaining epishelf lake in the Arctic, a tidally influenced freshwater layer overlying denser seawater that harbours a unique ecosystem that owes its existence to the integrity of the Milne Ice Shelf and input of meltwater runoff from the Milne Glacier catchment. The primary aims of this project are to: 1) Provide the first comprehensive oceanographic description of the Milne Fjord system; 2) Estimate freshwater input to the fjord; 3) Determine the mass, heat, salt and energy flux of the ocean-epishelf lake-ice shelf-glacier tongue system; 4) Determine how the system evolves over a full annual cycle; 5) Describe the physical processes contributing to the stability or collapse of the system. This work will enable improved understanding of how ocean and epishelf lake dynamics relate to ice shelf and glacier tongue stability. Numerical modeling of these processes will help predict how changes in climate and meltwater flux will alter this system, leading to greater insights into recent and past ice shelf break-up events along the coast of northern Ellesmere Island.
Listen to a CBC radio interview with PhD Candidate Andrew Hamilton on recent changes on Ellesmere Island (August 2013):
(1) England, J. H., et al. 2008. Geophys. Res. Lett., 35, L19502.; (2) Antoniades, D. et al. 2011. PNAS, doi/10.1073/pnas.1106378108; (3) Mueller, D. R. et al. 2003. Geophys. Res. Lett. 30: 2031, doi:10.1029/2003GL017931.; (4) Copland, L. et al. 2007. Geophys. Res. Lett., 34, L21501.; (5) Mueller, D.R., et al. 2008.. EOS, Trans., Am. Geophys. Union, 89(49), 502-503.; (6) Johnson, H.L., et al. 2011. J. Geophys. Res., 116, C01003. ; (7) Straneo, F. et al. 2010. Nature Geosci. doi: 10.1038/NGEO1109; (8) Gardner, A. et al. 2011. Nature Geosci. doi:10.1038/nature10089.