Abstract
Several recent studies predict that the West Antarctic Ice Sheet will become increasingly unstable under warmer conditions. Insights on such change can be assisted through investigations of the subglacial landscape, which contains imprints of former ice-sheet behavior. Here, we present radio-echo sounding data and satellite imagery revealing a series of ancient large sub-parallel subglacial bed channels preserved in the region between the Möller and Foundation Ice Streams, West Antarctica. We suggest that these newly recognized channels were formed by significant meltwater routed along the ice-sheet bed. The volume of water required is likely substantial and can most easily be explained by water generated at the ice surface. The Greenland Ice Sheet today exemplifies how significant seasonal surface melt can be transferred to the bed via englacial routing. For West Antarctica, the Pliocene (2.6–5.3 Ma) represents the most recent sustained period when temperatures could have been high enough to generate surface melt comparable to that of present-day Greenland. We propose, therefore, that a temperate ice sheet covered this location during Pliocene warm periods.
Highlights
The marine-based West Antarctic Ice Sheet (WAIS) is considered highly susceptible to ocean and climate warming (Pritchard et al, 2012; Joughin et al, 2014), experiencing numerous oscillations since its formation (Naish et al, 2009)
radio-echo sounding (RES) data and satellite imagery reveal preserved, major subglacial channels incised into subglacial topography in the region between the Möller and Foundation Ice Streams (MIS and FIS, respectively) in West Antarctica
DR1 and DR2 in the Data Repository). Topography in this region is characterized by hills and valleys, predominantly lies below sea level, and marks the geological boundary between West and East Antarctica (Jordan et al, 2013)
Summary
The marine-based West Antarctic Ice Sheet (WAIS) is considered highly susceptible to ocean and climate warming (Pritchard et al, 2012; Joughin et al, 2014), experiencing numerous oscillations since its formation (Naish et al, 2009). While radio-echo sounding (RES) is the primary tool used to map topography beneath modern ice sheets (Fretwell et al, 2013), satellite imagery of the ice surface has been shown to provide insights where RES is unavailable (Ross et al, 2014). Using this combination of data sets, we have identified a series of large (kilometer-scale), linear subglacial features, which we interpret as preserved, ancient subglacial meltwater channels. Our findings have implications for the processes driving former ice-sheet oscillations and the response of the WAIS to warmer climatic conditions
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