Airborne geophysical investigations of conditions at the bed of fast-flowing outlet glaciers of large Canadian Arctic ice caps

Recent work has shown that the single largest unknown in assessing the contribution of mountain glaciers and ice caps to contemporary global sea-level rise is the rate of mass loss by iceberg calving from large Arctic ice caps (Radic and Hock, 2011, Nature Geoscience). The largest ice caps in the Arctic, and indeed the largest ice masses outside the Antarctic and Greenland ice sheets, are those of the Canadian Arctic islands. Importantly, new findings indicate that, for 2004-2009, a sharp increase in the rate of mass loss also makes the Canadian Arctic Archipelago the single largest contributor to global sea-level rise outside Greenland and Antarctica (Gardner et al., 2011, Nature). Each of these large Canadian ice caps is divided into a series of drainage basins that flow into fjords via narrow, heavily crevassed fast-flowing outlet glaciers which dissect the islands' fringing mountains. A major question for scientists and policymakers is, therefore, how these ice caps will continue to react to the temperature rises that are predicted for the 21st century, noting that Atmospheric General Circulation Models predict that temperature rise will be significantly greater in the Arctic than at lower latitudes. Numerical modelling of large ice masses is constrained, however, by a lack of knowledge of the geometry and nature of the bed of these outlet glaciers. We will acquire geophysical data from ice-cap outlet glaciers draining the large ice caps on Ellesmere and Devon islands in the Canadian Arctic using an airborne ice-penetrating radar, laser altimeter, gravimeter, magnetometer and GPS instruments. We will focus on three key areas of each drainage basin: the heavily crevassed fast-flowing outlet glaciers themselves, an upper transition zone between the ice-cap interior and the narrow outlet glaciers; and the grounding zone marking the transition to floating ice tongues at the head of some Canadian High-Arctic fjords. Our scientific objectives are: (a) to determine ice-surface and subglacial-bed elevation; (b) to characterize the substrate, in particular whether it is bedrock or deformable sediment; (c) to establish the distribution of subglacial melting; (d) to reveal basal character changes at the transition zones between inland ice, outlet glaciers and the grounding zone; (e) to provide new estimates of outlet glacier calving fluxes and their variability on up to decadal timescales. This information, integrated with satellite datasets on outlet-glacier surface motion and our earlier observations of the regional-scale geometry of these ice caps, will provide fundamental boundary conditions for the numerical modelling of these ice caps and, thus, how they may respond to atmospheric and ocean warming over the coming decades, with implications for sea-level rise.

This research project is focused on the behaviour of the major outlet glaciers of the ice caps of the Canadian Arctic islands. Mass loss from the ice of the Canadian Arctic islands is the largest contributor to sea-level rise outside the Great Ice Sheets. Our work will provide new information on the boundary conditions beneath these narrow outlet glaciers or gateways. These boundary conditions will yield information not only on the shape of the underlying bed, but also on subglacial patterns and processes that lead to fast flow including the nature of the substrate and the presence and character of subglacial water. It is largely through the reduction of basal friction that these outlet glaciers flow fast.
The enhanced understanding of these basal processes is of significance to the whole glaciological community. In particular, the ice-sheet numerical modeling community requires the detailed specification of the basal boundary conditions in these ice-sheet outlet glaciers in order to reconstruct present outlet glacier flow, and to predict how this may change over the coming century. Our findings will be published in ISI-recognised journals, and talks and posters at international conferences (e.g. AGU, EGU) will allow the presentation of our research to the scientific community.
Governments at regional and national level also need to know about environmental change issues and, in this case, what the rate of sea-level is likely to be in the next few decades. This is so that they can take remedial action concerning, for example, the provision of coastal defense systems. They will be better informed as a result of our work. We have strong links to several government departments, to whom we provide advice. The PI and Co-Is have also been invited to address groups ranging from MPs to regional political decision-makers, and we will continue to project our research in response to such requests.
The oil and gas industry is surveying the shelf seas of the Canadian Arctic for exploration and possible exploitation of hydrocarbons. The hydrocarbons industry will benefit through the enhancement of our observational knowledge, and ability to predict, the flux of icebergs from these ice caps and the natural hazards to shipping and engineering structures that result. The PI has given seminars to the Arctic groups of several hydrocarbons companies (e.g. BP, Eni). The PI also participates in the university's short courses for business leaders, providing continuing opportunities to project our research.
Finally, the general public has become increasingly engaged with environmental change research and its implications in the past decade or so. As a contribution to our understanding of the cryospheric component of environmental change, our work will be projected to the public through various media outlets. Dialogue will take place with the television, radio and print media. Cambridge and Edinburgh universities each have press offices, and newsworthy stories relating to this research project will be circulated to the media through these channels. The PI and Co-Is have a long record of working with the media. Britain's only dedicated Polar Museum is located in the Scott Polar Research Institute. A recent grant of £1 million from the Heritage Lottery Fund has allowed the complete redesign and refurbishment of the museum. About one-fifth of the permanent gallery space is devoted to the environmental significant of the polar regions to the whole planet and to humankind. We will use our additional temporary gallery space which hosts a series of special exhibitions each year (and our virtual web presence) to project our findings to the 45,000 or so members of the public who visit the museum annually. It should be noted that our museum also receives about 120 formal school visits per year, and thus the outreach to children studying several parts of the national curriculum is assured.