Influences on Antarctic Ice

The floating ice shelves around Antarctica are key to buttressing land-based ice. Observations, simulations and analyses from around Antarctica now identify mechanisms that lead to basal melting of these vulnerable shelves.

Excessively warm and fresh surface water along the Amery Ice Shelf, Antarctica, in 2017 led to more ice melt and delayed dense water formation, according to analyses of in situ observations.

At the calving front of Nansen Ice Shelf, Antarctica a 10-km wide eddy dominated the local circulation in austral summer 2018/19 and led to substantial vertical heat transport, according to rare observations with an autonomous glider and microstructure turbulence measurements.

Positive phases of the Southern Annular Mode lead to enhanced basal melt overall in the Antarctic ice shelves, with strong losses in the Bellingshausen and Western Pacific sectors and gains in the Amundsen Sea, according to ice-ocean model experiments.

Regional climate warming amplified the exceptional heatwave on the Antarctic Peninsula observed in February 2020, suggest analyses of atmospheric flow analogs.

Ice loss from the Amundsen Sea sector of West Antarctica is rapidly accelerating. Here, the authors reveal that this region also underwent thinning and retreat from 9 to 6 thousand years ago, due to atmospheric connections with a warming tropical Pacific.

Most of the eastern Antarctic Peninsula’s coastline has undergone uninterrupted advance since the early 2000s due to enhanced near-shore sea ice, according to satellite observations and reanalysis data.

The most intense atmospheric rivers to hit the Antarctic Peninsula induce extremes in temperature, surface melt, sea ice disintegration or swell that destabilize the ice shelves with 40% probability, suggest analyses of observations and regional climate model simulations.

A new metric measuring the exposure of the Antarctic coastline to full open-ocean conditions reveals strong regional and seasonal change and variability occurred over the past four decades due to the loss and/or gain of an offshore sea-ice buffer.

The rate of deformation in Antarctic ice shelves is proportional to stress to the power of 4, not 3 as often used in models, according to a calibration of Glen’s Flow Law with satellite remote sensing data from Antarctic ice shelves.

The growth of the West Antarctic Ice Sheet was inhibited by incursions of relatively warm circumpolar deep water as early as the Eocene-Oligocene transition, according to seismic imaging of a sediment drift on the shelf of the Amundsen Sea Embayment.

The Pope, Smith and Kohler glaciers in West Antarctica have exhibited faster than expected retreat rates in recent years, according to grounding-line observations from satellite radar interferometry.

Antarctic sea ice extent is thought to be stable or increasing, in contrast to Arctic declines. Estimates of seasonal Antarctic sea ice from reconstructions show that increases are confined to the satellite era, post-1979, with substantial decreases in the early and mid-twentieth century.

The Antarctic Ice Sheet’s sea-level contribution in a high-emissions scenario is indistinguishable from that in a low-emissions scenario for the next century, but its long-term contribution depends on warming this century, according to ice sheet simulations and an emulator-based analysis.

Circumpolar Deep Water is efficiently transported towards the shelf break off Totten Ice Shelf, East Antarctica by cyclonic eddies, suggest comprehensive hydrographic observations.

Foehn warming played a dominant role in the generation of record-high temperatures on the Antarctic Peninsula in February 2020, in line with mechanisms of previous warm summer events, suggests an investigation of reanalysis data.

Direct observations at the grounding zone of a tidewater glacier ice cliff in the Weddell Sea, obtained by remotely operated vehicle, reveal evidence for a freeze-on of meltwater above the seafloor, grounding line retreat and high productivity.

A highly variable meltwater distribution with interlinked layers and columns is found in the Amundsen Sea in winter, and it may sustain polynyas in the region, according to hydrographic data obtained by seals.