Recent changes in the MCMURDO ICE SHELF TRANSITION ZONE and Hut Point Peninsula, West Antarctica

McMurdo Ice Shelf (MIS) and Ross Island act as both lateral margins and pinning points for the Ross Ice Shelf, as well as logistic hubs for the United States and New Zealand Antarctic Programs. Recent thinning and retreat of MIS has motivated an evaluation of the future stability of this critical region and potential adaptation. If MIS were to collapse, it could initiate sizeable teleconnections across West Antarctica, as well as stifle Antarctic research that relies on MIS/Ross Island-based logistics. One logistics component already experiencing change is the Transition Zone (TZ) road, which connects MIS with the research stations on Hut Point Peninsula (HPP), Ross Island. Here we assess the vulnerability of the TZ road and a proposed rerouting location (TZ Hillside), by using a combination of in situ, remote sensing, and numerical modeling approaches. We evaluate overall elevation change by differencing late summer, WorldView-derived, DEMs (2011-2015), and evaluate the practicality of both a stable ice surface and bare earth road using a numerical ice volume flux model, informed by GPR and GPS measurements of ice thickness and velocity (2015-2016). Results show overall ice elevation change of up to 3 m, and 204 +/- 24 m(3) a(-1) of ice flux across the TZ Hillside. Combined, these results indicate that the TZ Hillside is unsuitable for either type of road, and point to MIS terminus retreat and TZ Hillside melt as a continuing risk for TZ stability, which could prelude broader changes.