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The Cryosphere An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/tc-2017-19
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
16 Mar 2017
Review status
A revision of this discussion paper was accepted for the journal The Cryosphere (TC) and is expected to appear here in due course.
Dynamic response of an Arctic epishelf lake to seasonal and long-term forcing: implications for ice shelf thickness
Andrew K. Hamilton1,2, Bernard E. Laval1, Derek R. Mueller2, Warwick F. Vincent3, and Luke Copland4 1Department of Civil Engineering, University of British Columbia, Vancouver, British Columbia, Canada
2Geography and Environmental Studies, Carleton University, Ottawa, Ontario, Canada
3Department of Biology and Centre for Northern Studies (CEN), Université Laval, Quebec City, Quebec, Canada
4Department of Geography, Environment, and Geomatics, University of Ottawa, Ottawa, Ontario, Canada
Abstract. Changes in the depth of the freshwater-seawater interface in epishelf lakes have been used to infer long-term changes in the thickness of ice shelves, however, little is known about the dynamics of epishelf lakes and what other factors may influence their depth. Continuous observations collected between 2011 and 2014 in the Milne Fiord epishelf lake, in the Canadian Arctic, showed that the depth of the halocline varied seasonally by up to 3.3 m, which was comparable to interannual variability. The seasonal depth variation was controlled by the magnitude of surface meltwater inflow and the hydraulics of the inferred outflow pathway, a narrow basal channel in the Milne Ice Shelf. When seasonal variation and an episodic mixing of the halocline were accounted for, long-term records of depth indicated there was no significant change in thickness of ice along the basal channel from 1983 to 2004, followed by a period of steady thinning at 0.50 m a-1 between 2004 and 2011. Rapid thinning at 1.15 m a-1 then occurred from 2011 to 2014, corresponded to a period of warming regional air temperatures. Continued warming is expected to lead to the breakup of the ice shelf and the imminent loss of the last known epishelf lake in the Arctic.

Citation: Hamilton, A. K., Laval, B. E., Mueller, D. R., Vincent, W. F., and Copland, L.: Dynamic response of an Arctic epishelf lake to seasonal and long-term forcing: implications for ice shelf thickness, The Cryosphere Discuss., https://doi.org/10.5194/tc-2017-19, in review, 2017.
Andrew K. Hamilton et al.
Andrew K. Hamilton et al.

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Short summary
Meltwater runoff trapped by an ice shelf can create a freshwater lake floating directly on seawater. We show that the depth of the freshwater-seawater interface varies substantially due to changes in meltwater inflow and drainage under the ice shelf. By accounting for seasonality the interface depth can be used to monitor long-term changes in the thickness of ice shelves. We show that the Milne Ice Shelf, Ellesmere Island, was stable before 2004, after which time the ice shelf thinned rapidly.
Meltwater runoff trapped by an ice shelf can create a freshwater lake floating directly on...
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