Seasonal subglacial hydrological evolution and impact on ice dynamics at a High Arctic glacier

• Main Authors: Bingham, RG, Nienow, PW, Sharp, MJ, Boon, S
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2001
• Subjects: Arctic; Ellesmere Island; John Evans Glacier; Climate change
• Online Access: https://hdl.handle.net/1983/dcc37276-82f3-4153-b623-306de40c1b33; https://research-information.bris.ac.uk/en/publications/dcc37276-82f3-4153-b623-306de40c1b33

An improved understanding of the response of Arctic glaciers to climate change is required in order to provide inputs for models of global sea-level change. Currently, our knowledge of subglacial hydrological processes in polar regions, and how they impact upon patterns of ice dynamics, remains poor. However, recent research has shown that subglacial hydrology is a crucial determinant of ice dynamics and ice profiles in temperate regions - could this also be the case for polythermal ice masses? During summer 2000, intensive field investigations were undertaken at John Evans Glacier, a polythermal valley glacier situated on eastern Ellesmere Island in the Canadian High Arctic, in order to: i) determine the subglacial drainage system structure, and whether it evolves over the course of the melt season; and ii) investigate whether variations in subglacial hydrology affected rates of glacier motion. Known quantities of fluorescent dye were periodically injected into the englacial system via moulins, and dye emergence was detected in a single stream emerging from the base of the glacier at the snout 5 km downstream. In early June, dye return curves were highly dispersed and dye velocities were low (0.14 m/s), implying that inefficient distributed drainage was taking place. By late July, little dispersion of dye was observed, and dye velocities reached 0.69 m/s. These results suggest that the subglacial drainage system evolved over the course of the melt season. Frequent survey measurements made during the season reveal that much of the surface of the lower sector of the glacier was uplifted and experienced highest horizontal velocities during late June. This period of increased motion may be a direct result of large supraglacial inputs entering a still-inefficient distributed subglacial drainage system at this time. We emphasise the importance of understanding these processes further in order to provide realistic data for future models of Arctic glacier response to climate change. An improved understanding of the ...