Physical geography seminar

Dr Chris Stokes, Department of Geography, Durham University

Chair: Tony Payne

Abstract:

Recent observations in Greenland and Antarctica reveal major changes in the dynamics of rapidly flowing ice streams/outlet glaciers (typically retreat and thinning), heightening concern about their future contribution to sea level. The danger of extrapolating short-term trends to draw conclusions about the future is, however, widely acknowledged, and numerous workers have sought to extend the observational record through investigation of palaeo-ice streams at millennial time-scales. Most palaeo-studies, however, are restricted to single ice streams or small numbers of ice streams. This paper presents the first preliminary attempt at synthesising the behaviour of an entire population of ice streams in the North American (Laurentide) Ice Sheet during deglaciation, with a view to assessing their overall role in ice sheet demise. Together with a data-calibrated numerical ice sheet model, we also explore ice stream activity during the growth of the ice sheet. During deglaciation, the focus of mass loss associated with ice streaming changes through time: some migrate inland during margin retreat, other others switch off, and yet others switch on. The overall trend, however, is that ice stream activity appears to decrease, suggesting that surface-driven melt becomes increasingly more important in terms of mass loss.

All welcome.