Ice shelves of Antarctica

Ice shelves of Antarctica
Paleo nim · CC BY-SA 4.0 · source
Name	Antarctic ice shelves
Type	Ice shelf
Location	Antarctica
Area	~1.54 million km² (historical estimates)
Status	Variable; widespread thinning and losses since late 20th century

Ice shelves of Antarctica are floating extensions of the Antarctic ice sheet where grounded glacier and ice stream flow meets the Southern Ocean. These features, including the Ross Ice Shelf, Filchner–Ronne Ice Shelf, and Larsen Ice Shelf, serve as buttresses for inland West Antarctica and East Antarctica ice, modulate sea level contributions, and mediate interactions among atmosphere, oceanography, cryosphere and climate change processes.

Overview

Antarctic ice shelves fringe coastal regions of Antarctic Peninsula, Ross Sea, and Weddell Sea, ranging from the vast Ross Ice Shelf adjacent to McMurdo Sound to smaller, vulnerable shelves such as parts of the Larsen Ice Shelf near Graham Land. They form part of the broader cryosphere and are monitored by agencies including NASA, European Space Agency, British Antarctic Survey, and Australian Antarctic Division using satellite platforms like Landsat, Sentinel-1, ICESat, and ERS-1. Ice shelves interact with regional phenomena such as Antarctic Circumpolar Current, Amundsen Sea Low, and events like El Niño–Southern Oscillation through coupled climate teleconnections.

Formation and Structure

Ice shelves originate where grounded ice sheet flow exceeds ablation and floats on the ocean, producing a basal freeboard and a grounding line that marks the transition from grounded to floating ice. Structural elements include basal channels, melt ponds on the surface, and crevasse fields linked to stresses from tributary glacier flow such as from Pine Island Glacier and Thwaites Glacier. Thermodynamic processes involve sea ice formation, oceanic heat transport beneath shelves via Circumpolar Deep Water, and refreezing in polynyas near features like Ross Ice Shelf and George V Coast. Morphology is influenced by bed topography beneath grounded ice, including subglacial basins like the West Antarctic Rift System and ice streams that drain into shelves.

Major Antarctic Ice Shelves

Key shelves include the Ross Ice Shelf—the largest, bordering Victoria Land and receiving inflow from the Hatherton Glacier system; the Filchner–Ronne Ice Shelf in the Weddell Sea incorporating the Ronne Ice Shelf and Filchner Ice Shelf; and the series of shelves along the Antarctic Peninsula such as the Larsen Ice Shelf complex (Larsen A, Larsen B, Larsen C). Other notable features are the Getz Ice Shelf in the Amundsen Sea, the Amery Ice Shelf in East Antarctica adjacent to Mawson Station, and the PIIS (Pine Island Ice Shelf) front near Pine Island Glacier. These shelves are referenced in scientific work by institutions like SCAR and nations maintaining research stations including Rothera Research Station, Halley Research Station, McMurdo Station, and Casey Station.

Dynamics, Mass Balance, and Ice-Ocean Interactions

Ice-shelf dynamics link calving, basal melt, and grounding-line migration, driven by forces documented by researchers at Scripps Institution of Oceanography, British Antarctic Survey, Columbia University, and University of Washington. Basal melting is modulated by inflow of warm Circumpolar Deep Water and intrusions mediated by continental shelf processes near features like the Antarctic Slope Front. Mass balance measurements combine satellite altimetry from ICESat-2, gravity change from GRACE and GRACE-FO, and radar sounding from Operation IceBridge to quantify thinning, grounding-line retreat, and changes in ice discharge from outlets such as Thwaites Glacier and Pine Island Glacier. Calving events produce icebergs cataloged by International Ice Patrol and influence ocean stratification, while isostatic adjustments relate to glacial isostatic adjustment models.

Historical Changes and Recent Collapse Events

Several shelves experienced rapid retreat and collapse in the late 20th and early 21st centuries. The dramatic disintegration of Larsen B in 2002 followed prolonged warming on the Antarctic Peninsula and preceded earlier losses like Wordie Ice Shelf retreat. More recent concerns center on accelerating thinning of the Pine Island Glacier and Thwaites Glacier outlets, and fracture propagation in Larsen C culminating in major iceberg A-68 calving. These events are interpreted through frameworks such as marine ice sheet instability and marine ice cliff instability debated in literature from groups including the Intergovernmental Panel on Climate Change and researchers at National Snow and Ice Data Center.

Ecological and Climate Significance

Ice shelves shape coastal marine ecosystems by modulating freshwater fluxes, nutrient delivery, and habitat for organisms studied by teams at institutions like Australian Antarctic Division, Monash University, Woods Hole Oceanographic Institution, and University of Cape Town. Retreat and collapse open fjords and embayments, altering primary productivity and impacting species linked to Antarctic krill, penguin colonies (e.g., Adélie penguin and Gentoo penguin), and benthic communities documented at locales such as Prydz Bay and Pine Island Bay. Climatically, shelf loss reduces buttressing, increasing grounded ice discharge and contributing to global sea level rise projections considered by IPCC assessments, national adaptation planning, and international efforts such as the Antarctic Treaty System.

Category:Glaciers of Antarctica