Antarctic ice-shelf advance driven by anomalous atmospheric and sea-ice circulation

The disintegration of the eastern Antarctic Peninsula's Larsen A and B ice shelves has been attributed to atmosphere and ocean warming, and increased mass losses from the glaciers once restrained by these ice shelves have increased Antarctica's total contribution to sea-level rise. Abrupt recessions in ice-shelf frontal position presaged the break-up of Larsen A and B, yet, in the -20 years since these events, documented knowledge of frontal change along the entire -1,400-km-long eastern Antarctic Peninsula is limited. Here, we show that 85% of the seaward ice-shelf perimeter fringing this coastline underwent uninterrupted advance between the early 2000s and 2019, in contrast to the two previous decades. We attribute this advance to enhanced ocean-wave dampening, ice-shelf buttressing and the absence of sea-surface slope-induced gravitational ice-shelf flow. These phenomena were, in turn, enabled by increased near-shore sea ice driven by a Weddell Sea-wide intensification of cyclonic surface winds around 2002. Collectively, our observations demonstrate that sea-ice change can either safeguard from, or set in motion, the final rifting and calving of even large Antarctic ice shelves.

Automated summary

The study finds that 85% of the seaward ice-shelf perimeter along the 1400-km-long eastern Antarctic Peninsula has experienced continuous advance between the early 2000s and 2019, in contrast to the two previous decades. This advance is attributed to enhanced ocean-wave dampening, ice-shelf buttressing, and the absence of sea-surface slope-induced gravitational ice-shelf flow. These phenomena are enabled by increased near-shore sea ice driven by a Weddell Sea-wide intensification of cyclonic surface winds around 2002. The findings demonstrate that sea-ice change can either protect or trigger the final rift and calving of even large Antarctic ice shelves.