Mass balance reassessment of glaciers draining into the Abbot and Getz Ice Shelves of West Antarctica

We present a reassessment of input-output method ice mass budget estimates for the Abbot and Getz regions of West Antarctica using CryoSat-2-derived ice thickness estimates. The mass budget is 8 +/- 6 Gt yr(-1) and 5 +/- 17 Gt yr(-1) for the Abbot and Getz sectors, respectively, for the period 2006-2008. Over the Abbot region, our results resolve a previous discrepancy with elevation rates from altimetry, due to a previous 30% overestimation of ice thickness. For the Getz sector, our results are at the more positive bound of estimates from other techniques. Grounding line velocity increases up to 20% between 2007 and 2014 alongside mean elevation rates of -0.67 +/- 0.13 m yr(-1) between 2010 and 2013 indicate the onset of a dynamic thinning signal. Mean snowfall trends of -0.33 m yr(-1) water equivalent since 2006 indicate recent mass trends are driven by both ice dynamics and surface processes. Plain Language Summary There are large differences in mass balance estimates (the net loss or gain of ice mass) from independent techniques for glaciers draining into the Abbot and Getz Ice Shelves of West Antarctica. This is believed to be primarily due to previous uncertainties in the knowledge of ice thickness in these regions at the grounding line (the point where the ice sheet detaches from the bedrock and begins to float). We use new higher-accuracy ice thickness measurements derived from ESA's CryoSat-2 satellite to reassess the mass balance for these regions for the 2006-2008 period. Our results provide better agreement with other techniques and resolve outstanding discrepancies over the Abbot region in particular. We also find that grounding line retreat, a key indicator of ice sheet imbalance, has likely to have been occurring over the Getz region since this period. Our results demonstrate the ability for the satellite to more accurately calculate the mass loss from these regions and better constrain their subsequent contribution to sea level rise.