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.