Antarctic Ice Sheet

Antarctic Ice Sheet
NASA Goddard's Scientific Visualization Studio · Public domain · source
Name	Antarctic Ice Sheet
Caption	Satellite view of Antarctica
Area	~14 million km²
Volume	~26.5 million km³
Highest point	Dome A
Thickness	up to ~4,800 m
Status	changing

Antarctic Ice Sheet The Antarctic Ice Sheet is the vast continental-scale ice mass covering the continent of Antarctica and surrounding islands. It is the largest single mass of ice on Earth and a dominant component of the Cryosphere that influences global Climate change and Sea level rise. The ice sheet is divided broadly into the East Antarctic Ice Sheet and the West Antarctic Ice Sheet, each interacting with atmospheric, oceanic, and geological systems studied by organizations such as the British Antarctic Survey, the United States Antarctic Program, and the Scientific Committee on Antarctic Research.

Overview

The ice sheet originated during the Cenozoic cooling after the breakup of Gondwana and the opening of the Southern Ocean gateways near the Eocene–Oligocene extinction event. Its mass balance integrates accumulation from precipitation over the Antarctic Plateau and losses from calving at ice shelves like the Ross Ice Shelf and the Filchner–Ronne Ice Shelf, and from basal melting influenced by the Antarctic Circumpolar Current. The ice sheet overlies bedrock features including the West Antarctic Rift System and subglacial basins such as the Wilkes Subglacial Basin and Amundsen Sea Embayment, affecting ice flow and stability in ways explored by missions including Operation IceBridge and satellites like ICESat and GRACE.

Physical characteristics

Thickness varies from a few hundred meters along the margins to nearly 4,800 meters at locations such as Dome Argus and Dome A. The surface elevation ranges from coastal sea level to the high interior plateau, featuring grounded ice and floating ice shelves that buttress outlets like Pine Island Glacier and Thwaites Glacier. The ice sheet contains ancient ice cores retrieved from sites like Vostok Station and EPICA that preserve records of greenhouse gases during glacial cycles tied to the Milankovitch cycles. Bed conditions beneath the ice range from frozen beds to warm, wet beds with subglacial lakes including Lake Vostok and Lake Whillans, and topography mapped by projects such as BEDMAP.

Glaciology and dynamics

Ice dynamics are controlled by processes including internal deformation, basal sliding, and calving, modulated by feedbacks involving meltwater, sediment, and structural features like ice streams such as the Siple Coast ice streams. Marine ice sheet instability and marine ice cliff instability theories address retreat in marine-based sectors such as the Amundsen Sea Embayment and the Getz Ice Shelf margins. Numerical models used by the Intergovernmental Panel on Climate Change and research centers like the Potsdam Institute for Climate Impact Research implement ice flow physics (e.g., Glen's flow law) and couple to ocean models from groups like NOAA to simulate grounding line migration and potential thresholds identified in studies of Thwaites Glacier.

Climate interactions and recent changes

The ice sheet responds to changes in atmospheric circulation patterns such as the Southern Annular Mode and to oceanic forcing including warm water incursions via the Circumpolar Deep Water that enhance basal melting beneath ice shelves. Observational programs by NASA and the European Space Agency using satellites like CryoSat and Sentinel-1 document accelerating mass loss in sectors connected to the Amundsen Sea and parts of the West Antarctic Ice Sheet. Paleoclimate evidence from Antarctic ice cores links past interglacials such as the Last Interglacial and events like the Pleistocene deglaciations to substantial ice sheet retreat, while contemporary anthropogenic warming traced to emissions from industrial regions examined in reports by the Intergovernmental Panel on Climate Change is implicated in recent trends.

Sea level rise and impacts

If fully melted, the ice sheet would raise global mean sea level by about 58 meters, affecting coastal regions worldwide from New York City to the Netherlands and island nations like Maldives. Contemporary contributions to sea level rise come primarily from dynamic thinning and increased iceberg calving in West Antarctica, with particular concern focused on the potential collapse of sectors anchored in sub-sea-level basins such as the Thwaites Glacier catchment. Assessment frameworks used by bodies including the United Nations Framework Convention on Climate Change and national agencies inform adaptation planning for cities such as Miami and infrastructure governed by entities like Port Authority of New York and New Jersey.

Human activity and scientific research

Human presence in Antarctica is governed by the Antarctic Treaty System and supported by research stations including McMurdo Station, Amundsen–Scott South Pole Station, and Casey Station. Scientific research spans glaciology, paleoclimate, and marine studies conducted by multinational collaborations such as the International Thwaites Glacier Collaboration and field campaigns like ROSETTA-Ice. Key datasets are produced by programs including SCAR and repositories coordinated with institutions like Lamont–Doherty Earth Observatory and Scripps Institution of Oceanography. Human impacts are regulated under agreements like the Protocol on Environmental Protection to the Antarctic Treaty, while ongoing expeditions from organizations such as Australian Antarctic Division and Russian Antarctic Expedition continue to refine understanding of ice sheet behavior and risks to global systems.

Category:Antarctica Category:Glaciology Category:Climate change