Investigating basal thaw as a driver of mass loss from the Antarctic ice sheet

<p>Contemporary mass loss from the Antarctic ice sheet primarily originates from the discharge of<br>marine-terminating glaciers and ice streams. The rate of mass loss is influenced by warming ocean<br>and atmospheric conditions, which lead to subsequent thinning or disintegration of ice shelves and<br>increased outflow of upstream grounded ice. It is currently unclear how the basal thermal state of<br>grounded ice could evolve in the future - for example as a result of accelerated ice flow or changes<br>in the ice sheet geometry - but a change in the basal thermal state could impact rates of mass loss<br>from Antarctica. Here, we use a combination of numerical simulations and ice-penetrating radar<br>analysis to investigate the influence of basal thawing on 100yr simulations of the Antarctic ice<br>sheet&#8217;s evolution. Using the Ice-sheet and Sea-level System Model, we find that thawing patches<br>of frozen bed near the ice sheet margin could drive mass loss extending into the continental<br>interior, with the highest rates of loss coming from the George V - Ad&#233;lie - Wilkes Land coast and<br>the Enderby - Kemp Land regions of East Antarctica. This suggests that the thawing of localized<br>frozen bed patches is sufficient to cause these East Antarctic regions to transition to an unstable<br>mass loss regime. We constrain model estimates of the basal thermal state using ice-penetrating<br>radar surveys and analyze radar characteristics including bed reflectivity and attenuation. In<br>combination, our work identifies critical regions of Antarctica where the ice-bed interface could<br>be close to thawing and where basal thaw could most impact mass loss.</p>