Subglacial controls on dynamic thinning at Trinity-Wykeham Glacier, Prince of Wales Ice Field, Canadian Arctic

ABSTRACT

Mass loss from glaciers and ice caps represents the largest terrestrial component of current sea level rise. However, our understanding of how the processes governing mass loss will respond to climate warming remains incomplete. This study explores the relationship between surface elevation changes (dh/dt), glacier velocity changes (du/dt), and bedrock topography at the Trinity-Wykeham Glacier system (TWG), Canadian High Arctic, using a range of satellite and airborne datasets. We use measurements of dh/dt from ICESat (2003–2009) and CryoSat-2 (2010–2016) repeat observations to show that rates of surface lowering increased from 4 m yr⁻¹ to 6 m yr⁻¹ across the lowermost 10 km of the TWG. We show that surface flow rates at both Trinity Glacier and Wykeham Glacier doubled over 16 years, during which time the ice front retreated 4.45 km. The combination of thinning, acceleration and retreat of the TWG suggests that a dynamic thinning mechanism is responsible for the observed changes, and we suggest that both glaciers have transitioned from fully grounded to partially floating. Furthermore, by comparing the separate glacier troughs we suggest that the dynamic changes are modulated by both lateral friction from the valley sides and the complex geometry of the bed. Further, the presence of bedrock ridges induces crevassing on the surface and provides a direct link for surface meltwater to reach the bed. We observe supraglacial lakes that drain at the end of summer and are concurrent with a reduction in glacier velocity, suggesting hydrological connections between the surface and the bed significantly impact ice flow. The bedrock topography thus has a primary influence on the nature of the changes in ice dynamics observed over the last decade.

Acknowledgements

Landsat and ASTER imagery were downloaded from the Earth Explorer Data portal (https://earthexplorer.usgs.gov), as well as the ASTER GDEM. Glacier outlines for the Prince of Wales Ice Field and Trinity-Wykeham Glacier catchment were downloaded from the GLIMS data viewer (https://glims.org/maps/glims). We thank the developers at the California Institute of Technology for the freely accessible COSI-corr plugin for ENVI (http://www.tectonics.caltech.edu/slip_history/spot_coseis/download_software.html). CAGE data were collected under NERC grant NE/K004999, and NASA OIB data were taken from Leuschen et al. (2010). We thank Toby Benham for assistance with the CAGE data. This is UTIG contribution 3519. We would also like to thank Prof. Timothy Warner as editor and three anonymous reviewers whose insightful comments greatly improved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

European Space Agency [4000114224/15/I-SBO]; Natural Environment Research Council [NE/K004999,NE/L002434/1].