Mass gains of the Antarctic ice sheet exceed losses

Abstract

Mass changes of the Antarctic ice sheet impact sea-level rise as climate changes, but recent rates have been uncertain. Ice, Cloud and land Elevation Satellite (ICESat) data (2003-08) show mass gains from snow accumulation exceeded discharge losses by 82±25Gta-1, reducing global sea-level rise by 0.23 mm a-1. European Remote-sensing Satellite (ERS) data (1992-2001) give a similar gain of 112±61 Gt a-1. Gains of 136 Gt a-1 in East Antarctica (EA) and 72 Gt a-1 in four drainage systems (WA2) in West Antarctic (WA) exceed losses of 97Gta-1 from three coastal drainage systems (WA1) and 29Gta-1 from the Antarctic Peninsula (AP). EA dynamic thickening of 147 Gt a-1 is a continuing response to increased accumulation (>50%) since the early Holocene. Recent accumulation loss of 11 Gta-1 in EA indicates thickening is not from contemporaneous snowfall increases. Similarly, the WA2 gain is mainly (60Gta-1) dynamic thickening. In WA1 and the AP, increased losses of 66±16Gta-1 from increased dynamic thinning from accelerating glaciers are 50% offset by greater WA snowfall. The decadal increase in dynamic thinning in WA1 and the AP is approximately one-third of the long-term dynamic thickening in EA and WA2, which should buffer additional dynamic thinning for decades.