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.

Expansion of the Ross Gyre increases poleward transport of Circumpolar Deep Water toward the Amundsen Sea and the West Antarctic Ice Sheet and has implications for oceanic heat supply to the continental shelf, according to numerical modelling.

Dronning Maud Land’s largest ice stream was thicker than today, rather than thinner as expected, following the Pliocene collapse of its buttressing ice shelf, likely because of high lateral stresses, suggest high-resolution ice-sheet model simulations.

Record-low sea ice coverage around Antarctica in 2022 and 2023 co-occurred with substantial subsurface ocean warming, which could be indicative of a change in the mechanisms that govern Antarctic sea ice, suggests an analysis of sea ice extent and ocean temperatures since 1979.

Large expansions and interglacial melting of the Antarctic ice-sheet during the warmer-than-present climate of the late Oligocene were driven by both bottom-up ocean warming and top-down atmospheric warming, suggests an analysis of high-resolution benthic foraminifera proxy records.

The Heimefrontfjella escarpment in Dronning Maud Land, East Antarctica divides inland precipitation-dominated ice dynamics from coastal dynamics dominated by grounding line migration, suggest inverse model simulations constrained by cosmogenic nuclide measurements.

Warming of the subsurface Southern Ocean played only a minor role in shrinking Antarctic Sea ice extent in 2016, but was critical for the persistence of negative anomalies between 2016 and 2021, according to coupled climate model simulations partially constrained by observations.

Decadal sea ice variability in the west Antarctic seas can be skillfully predicted, with highest skill in a decadal reforecast experiment where sea surface temperature, sea ice concentration and subsurface ocean temperature and salinity are initialized from observations.

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.

Systematic satellite, ocean and atmosphere records show the pace and extent of melting in West Antarctica vary by location, with glaciers flowing to the Amundsen Sea most sensitive to atmosphere‒ocean variability atop a marine ice-sheet instability.

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.