Assessment of Antarctic Ice Sheet mass balance from 2005 to 2016

Abstract

The Antarctic ice sheet is an important indicator of climate change and a driver of sea level rise, with a volume in sea level equivalent terms of 58.3 m. Its tiny change could have a significant impact on the global sea mean level, which is considered to be one of the most serious consequences of future climate change. Therefore, understanding where and how the Antarctic ice mass changes is of societal importance. Considering the few assessments of the interannual change in the Antarctic mass balance, the objective of this paper is to demonstrate the estimation and uncertainty of the annual material balance of the Antarctic ice sheet from 2005 to 2016 based on the Input‒Output Method (IOM). The reasons for the change in the Antarctic ice sheet in various basins have been investigated, which will provide effective supporting data for further studies on the loss of the Antarctic ice sheet. Compared with other methods for estimating the Antarctic mass balance, the IOM quantifies the difference between mass gain through primarily snowfall and loss by sublimation, meltwater runoff and ice discharge. The advantage of this approach is that it separately calculates changes in each component at the scale of individual glacier drainage basins. Unquestionably, using different datasets could cause great variation. Here, we improve the method to finely evaluate the ice discharge over the grounding line, which can accurately calculate the flux at each outlet unit, ensure time series continuity, and define flux export widths. Finally, for the first time, year-to-year estimates of the ice flux from the islands around Antarctica have been achieved. Our results are within a reasonable range compared to the international estimates of the Antarctic ice sheet mass balance. During 2005—2016, Antarctica was basically in a loss state, with an average mass loss of 109.1 ± 34.9 Gt/a and a standard deviation of ± 84.1 Gt/a. West Antarctica dominated the mass loss and contributed 65.1% of the total loss, East Antarctica 26.4%, the Peninsula 4.5% and islands 4.0%. All of East Antarctica was in a positive mass balance and showed evident ice mass loss in some basins. The Peninsula fluctuated at zero equilibrium. The islands, accounting for 1.15% of the Antarctic ice sheet, were assessed individually for the first time and found to be in a persistent negative mass balance, with mass loss even exceeding the Peninsula in some years. On the whole, the change in the Antarctic ice sheet mass balance was dominated by the surface mass balance, which was mainly influenced by interannual variability in the climatological factors. From a small-scale perspective, the dynamic changes in ice flux at the grounding line due to ice shelves thinning and iceberg calving affected the mass balance in some regions, resulting in an increase in mass loss during the years of calving events. This study improves the IOM method for the detailed assessment of the Antarctic ice sheet mass balance during 2005—2016.