Wednesday, June 1, 2:00PM
Location: Revelle 4301
PhD Student, Stanford University, Stanford, CA
Development of subglacial drainage induces rapid ice flow rearrangement in West Antarctica
Subglacial meltwater modulates ice flow velocity from temperate alpine environments to the ice sheets on subannual time-scales. This short-term variability is due to the direct control of meltwater drainage on sliding properties at the ice-bed interface. In locations where ice flow is bounded laterally by topography, meltwater drainage only affects ice flow speed. This is not the case for ice streams, corridors of fast-flowing ice without lateral topographic constraints. In addition to subannual velocity changes, current and paleo-ice streams have exhibited large-scale morphological rearrangement on annual to centennial time scales. We propose that meltwater drainage has the ability to not only change ice flow velocity, but it can also induce these large-scale rearrangements of flow. We determine the effect of meltwater on the lateral extent of ice streams, called shear margins, by comparing theoretical models of subglacial drainage networks to surface observations of ice streams on the Siple Coast of West Antarctica. We find that the transition of subglacial drainage networks from distributed to efficient systems exerts direct control on the location and stability of shear margins. This suggests that ice streams would be expected to evolve at the time-scale of the drainage system. The impact of meltwater on shear margin location in combination with ice discharge’s dependence on (ice stream width)4 means that relatively small-scale drainage networks exert direct control on ice sheet-scale mass loss.