Climate variability a key driver of recent Antarctic ice-mass change

Multiple datasets show the Antarctic Ice Sheet has lost mass over recent decades and therefore contributed to sea-level rise. Short-term variability in ice mass has been associated partly with El Niño/Southern Oscillation (ENSO), for both the grounded ice sheet and its bounding ice shelves, but a connection with the Southern Annular Mode—the dominant climate mode in the region—is not fully clear. Here we show that satellite-based gravimetric estimates of ice-mass variability between 2002 and 2021 can be largely explained by a simple linear relation with both the Southern Annular Mode and lagged ENSO. Multiple linear regression reveals that the cumulative effects of the Southern Annular Mode and/or ENSO explain much of the decadal variability from the whole ice sheet down to individual drainage basins. A substantial portion of the net change in ice mass across the whole ice sheet between 2002 and 2021 can be attributed to a persistent forcing from a positive Southern Annular Mode. Understanding the drivers of variability in the Southern Annular Mode over this period, which are largely anthropogenic over multidecadal timescales, may be a pathway to partially attributing ice-sheet change to human activity.