Outburst flooding and the initiation of ice-stream surges in response to climatic cooling: A hypothesis

Outburst flooding from subglacial reservoirs and associated surging of ice-streams are caused by processes following climatic cooling that produce ice-shelf grounding on proglacial sills trapping subglacial water, according to an hypothesis presented here. Glaciers often advance into proglacial water bodies. Cooling may allow ice-shelf formation and advance causing grounding on a proglacial sill, trapping subglacial water. Ice-shelf freeze-on to the sill and development of a local reversal in ice-air surface slope over the sill then are likely, allowing ice thickening and water overpressurization. If basal thawing then occurs, as is likely, an outburst flood and a surge may be triggered. These processes may have been involved in Heinrich events, generation of Antarctic subglacial lakes, and meltwater scouring of some regions. (c) 2005 Elsevier B.V. All rights reserved.