Ocean melting has thinned Antarctica’s ice shelves at an increasing rate over the past two decades, leading to loss of grounded ice. The Ross Ice Shelf is currently close to steady state but geological records indicate that it can disintegrate rapidly, which would accelerate grounded ice loss from catchments equivalent to 11.6 m of global sea level rise. Here, we use data from the ROSETTA-Ice airborne survey and ocean simulations to identify the principal threats to Ross Ice Shelf stability. We locate the tectonic boundary between East and West Antarctica from magnetic anomalies and use gravity data to generate a new high-resolution map of sub-ice-shelf bathymetry. The tectonic imprint on the bathymetry constrains sub-ice-shelf ocean circulation, protecting the ice shelf grounding line from moderate changes in global ocean heat content. In contrast, local, seasonal production of warm upper-ocean water near the ice front drives rapid ice shelf melting east of Ross Island, where thinning would lead to faster grounded ice loss from both the East and West Antarctic ice sheets. We confirm high modelled melt rates in this region using ROSETTA-Ice radar data. Our findings highlight the significance of both the tectonic framework and local ocean–atmosphere exchange processes near the ice front in determining the future of the Antarctic Ice Sheet.
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The ROSETTA-Ice airborne survey data are available from http://www.ldeo.columbia.edu/polar-geophysics-group/data.
The code used to generate ocean simulations can be accessed at https://www.myroms.org/svn/src/. Modifications to the standard code used and ancillary input data are available on request from firstname.lastname@example.org.
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We gratefully acknowledge the support of the 109th Airlift Wing of the New York Air National Guard. We thank the United States Antarctic Program and staff of McMurdo Station seasons 2014–2018 and J. DeTemple during the development of the IcePod. This work was supported by the National Science Foundation 0958658, 1443534, 1443498, 1443677, 1443497 and 1341688, NASA NNX16AJ65G, the Moore Foundation, the Old York Foundation, the New Zealand Ministry of Business Innovation and Employment contract C05X1001, and New Zealand Antarctic Research Institute (NZARI no. 2014-11) funded Aotearoa New Zealand Ross Ice Shelf Programme (F.C.T. and G.O’B.). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the United States Government.