Assessing the potential for ice flow piracy between the Totten and Vanderford glaciers, East Antarctica

Abstract

Abstract. The largest regional drivers of current surface elevation increases in the Antarctic Ice Sheet are associated with ice flow reconfiguration in previously active ice streams, highlighting the important role of ice dynamics in mass balance calculations. Here, we investigate controls on the evolution of the flow configuration of the Vanderford and Totten glaciers – key outlet glaciers of the Aurora Subglacial Basin (ASB) – the most rapidly thinning region of the East Antarctic Ice Sheet (EAIS). We synthesise factors that influence the ice flow in this region and use an ice sheet model to investigate the sensitivity of the catchment divide location to changes in surface elevation due to thinning at the Vanderford Glacier (VG) associated with ongoing retreat and thickening at the Totten Glacier (TG) associated with an intensification of the east–west snowfall gradient. The present-day catchment divide between the Totten and Vanderford glaciers is not constrained by the geology or topography but is determined by the large-scale ice sheet geometry and its long-term evolution in response to climate forcing. Furthermore, the catchment divide migrates under relatively small changes in surface elevation, leading to ice flow and basal water piracy from the Totten to the Vanderford Glacier. Our findings show that ice flow reconfigurations occur not only in regions of West Antarctica like the Siple Coast but also in the east, motivating further investigations of past, and the potential for future, ice flow reconfigurations around the whole Antarctic coastline. Modelling of ice flow and basal water piracy may require coupled ice sheet thermomechanical and subglacial hydrology models constrained by field observations of subglacial conditions. Our results have implications for ice sheet mass budget studies that integrate over catchments and the validity of the zero flow assumption when selecting sites for ice core records of past climate.

Reply on RC2

“…These are associated with seasonal to diurnal surface melting cycles (Ehrenfeucht et al, 2023) and flood events, including jökulhlaups (Roberts, 2005). Ice stream 'water piracy', involving the re-routing of subglacial water from one ice stream to another, may occur in response to relatively small changes in glacial mass-balance or bed conditions (McCormack et al, 2023;Alley et al, 1994;Vaughan et al, 2008). It is likely that ongoing changes in cryosphere systems will increase the frequency and intensity of high-flow events in the future, and so increased sediment flux to the ocean (Delaney and Adhikari, 2020) To express the consequences of cryosphere change on marine systems, and to fully comprehend the implications of sedimentary records of the past and present cryosphere there is a need for a quantitative understanding of subglacial fluvial sediment transport systems (Delaney and Adhikari, 2020).…”

Modelling subglacial fluvial sediment transport with a graph-based model, GraphSSeT

“…These are associated with seasonal to diurnal surface melting cycles (Ehrenfeucht et al, 2023) and flood events, including jökulhlaups (Roberts, 2005). Ice stream 'water piracy', involving the re-routing of subglacial water from one ice stream to another, may occur in response to relatively small changes in glacial mass-balance or bed conditions (McCormack et al, 2023;Alley et al, 1994;Vaughan et al, 2008). It is likely that ongoing changes in cryosphere systems will increase the frequency and intensity of high-flow events in the future, and so increased sediment flux to the ocean (Delaney and Adhikari, 2020) To express the consequences of cryosphere change on marine systems, and to fully comprehend the implications of sedimentary records of the past and present cryosphere there is a need for a quantitative understanding of subglacial fluvial sediment transport systems (Delaney and Adhikari, 2020).…”