Variable Antarctic ice flux linked to ocean forcing, bed topography and ice shelf extent

Abstract: It has been widely reported that ice flux from the Antarctic Ice Sheet has increased over the preceding decades. The vast majority of these increases can be attributed to the ongoing destabilization of the Amundsen Sea sector in West Antarctica, with a much more limited change in East Antarctica. However, much less attention has been focussed on the temporal and spatial variations of ice flux in Antarctica over the observational period.

In this study we combine existing velocity products (ITS_LIVE and MEaSUREs) to create 12 timestamped velocity mosaics between 1999 and 2018 to investigate both overall trends in ice flux and the temporal and spatial variability across our observational period. Overall we report a 41±11 Gt yr-1 increase in ice flux, with a 45±8 Gt yr-1 increase West Antarctica and -4±7 Gt yr-1 decrease in East Antarctica. However, the rate of change has not been consistent through time and in the second half of our time series, between 2009-2010 and 2018 we report on a much more limited increase in net ice flux of the WAIS and EAIS (4±8 Gt yr-1). Despite the overall increase in ice flux in West Antarctica, clear periods of deceleration are observed in most individual glacier catchments. In East Antarctica, despite overall consistency, 3-10% variations in ice flux are observed at several major outlet glaciers (e.g. Denman, Totten, Frost, Cook, Matusevitch, Rennick). These variations can be linked to regional oceanic variability which we estimate by quantifying anomalies in the rate of ice shelf thickness change, along with highly localised differences in bed topography and ice shelf calving. In some cases, this can result in neighbouring catchments simultaneously undergoing opposing trends.

atmospheric sciencescryosphere sciencesocean sciencesatmospheric and oceanic physics

Audience: researchers in the topic

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