NSFGEO-NERC: Investigating the direct influence of meltwater on Antarctic Ice Sheet dynamics

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Surface melting is widespread around the periphery of Antarctica and predicted to increase significantly. This could impact sea-level rise by allowing surface-derived meltwater to reach the ice-sheet bed and modify glacier flow into the ocean. This mechanism has received little attention in Antarctica, partly because evidence for it happening today has only recently been published, by members of our team. This mechanism is likely to become increasingly important as Antarctica warms and we will take the first steps towards understanding and predicting these changes. We will test three hypotheses: (1) short-term changes in ice velocity indicated by satellite data result from surface meltwater reaching the bed of outlet glaciers in the Antarctic Peninsula, (2) this is widespread in Antarctica today, and (3) this results in a measurable increase in mean annual ice discharge.We propose a targeted field campaign supported by the British Antarctic Survey (BAS) on an Antarctic Peninsula outlet glacier, to test hypothesis 1 using a combination of well-established and more experimental techniques. BAS will support the fieldwork because of our field site's proximity to Rothera Research Station. Immediate outcomes will include a direct comparison of in situ melt rates (from energy-budget weather stations) and ice dynamic changes (from GPS and uncrewed aerial vehicles) and subglacial water flow (from passive seismometers and ice-penetrating radar). We will also conduct a continent-wide remote sensing survey, using synthetic aperture radar and multi-spectral imagery to comprehensively map meltwater on grounded ice (most similar efforts have focused on floating ice shelves) and short-term velocity variations. Comprehensive new datasets from the field and remote-sensing surveys will be used to test our three hypotheses.There is rapid growth in the glaciology community's interest in surface melting and hydrology on Antarctic ice shelves. This project will take the discipline in a new, but related direction and make important progress in understanding the different processes involved in the response of grounded ice to increasing melt rates. As one of the first projects to focus on this aspect of atmosphere/ice-dynamics coupling, we will produce early insights into both the drivers and implications of short-term changes in ice flow velocity caused by surface melting. For example, showing conclusively that meltwater directly impacts Antarctic ice dynamics would have significant implications for our understanding of the response of Antarctica to atmospheric warming, as it did in Greenland when the phenomenon was first detected there nearly 20 years ago. This work will also have implications for other fields, as surface-to-bed meltwater flow may have implications for ice rheology, subglacial hydrology, submarine melting and calving, ocean circulation, and ocean biogeochemistry.