Antarctic ice shelves

Antarctic ice shelves
Name	Antarctic ice shelves
Caption	Aerial view of an Antarctic ice shelf front
Location	Antarctica
Area	variable
Type	ice shelf

Antarctic ice shelves are floating extensions of the Antarctic Ice sheet that fringe the continent and mediate exchanges between the Antarctic Peninsula, West Antarctica, East Antarctica and the Southern Ocean. They influence the stability of grounded ice streams, the discharge of mass from the Antarctic Ice Sheet, and interactions with atmospheric systems such as the Southern Annular Mode and the Antarctic Oscillation. Research on Antarctic ice shelves connects work by organizations including the British Antarctic Survey, United States Antarctic Program, Australian Antarctic Division, and international programs such as the Scientific Committee on Antarctic Research.

Overview

Antarctic ice shelves form broad floating platforms along coasts like the Ross Ice Shelf and the Ronne Ice Shelf that buttress inland glaciers and regulate flow toward the Southern Ocean. Major shelves span regions defined by features such as the Amundsen Sea Embayment, the Weddell Sea, and the Bellingshausen Sea and interact with oceanic processes tied to the Antarctic Circumpolar Current and Circumpolar Deep Water. Their behavior is central to projections by bodies such as the Intergovernmental Panel on Climate Change and studies using frameworks from the International Geophysical Year legacy.

Formation and Structure

Ice shelves originate where grounded ice flows from catchments like the East Antarctic Ice Sheet and the West Antarctic Ice Sheet onto floating terrain near embayments and continental shelves. Structural elements include grounding lines near troughs like the Falkland Trough, basal channels formed by oceanic upwelling, and surface features such as rifts and crevasses (observed on the Larsen Ice Shelf). Layering records preserve signatures of volcanism from the West Antarctic Rift System and deposition events linked to the Antarctic Convergence.

Geographic Distribution

Antarctic ice shelves are unevenly distributed: large continuous shelves like the Ross Ice Shelf and the Ronne Ice Shelf occupy the Weddell Sea sector, while narrower, more fragmented shelves occur along the Antarctic Peninsula adjacent to the Drake Passage. Regions such as the Getz Ice Shelf and the Pine Island Glacier margin in the Amundsen Sea host dynamic smaller shelves. Shelf extent is mapped by missions including Landsat, MODIS, CryoSat-2, and the ICESat campaigns.

Dynamics and Processes

Ice-shelf dynamics are governed by processes including basal melting driven by intrusions of Circumpolar Deep Water, calving controlled by propagation of fractures and rifts, and grounding-line migration influenced by bed topography (e.g., reverse slopes in the Amundsen Sea Embayment). Interactions with atmospheric warming linked to El Niño–Southern Oscillation teleconnections and regional warming over the Antarctic Peninsula affect surface melting and hydrofracture. Numerical modeling efforts use codes developed in centers such as NERSC and groups at the University of Cambridge and University of Colorado Boulder.

Historical Changes and Collapse Events

Documented collapse events include dramatic disintegration of parts of the Larsen B Ice Shelf and retreat of Wordie Ice Shelf during late 20th and early 21st century episodes correlated with regional warming and ocean changes. Earlier paleo-records from ice cores and marine sediments show fluctuations during periods like the Last Glacial Maximum and the Holocene Thermal Maximum. Satellite-era observations by ERS-1, Envisat, and Sentinel-1 have documented accelerated retreat at fronts of Pine Island Glacier and Thwaites Glacier, prompting studies by consortia such as the Thwaites Glacier Collaboration.

Ecological Importance

Ice shelves create unique habitats by modulating ice-ocean interfaces where communities of krill, polar cod, and benthic fauna exploit polynyas and sub-ice-shelf cavities. Fronts and iceberg calving deliver refugia and nutrient inputs that support food webs connected to species like the Antarctic krill and apex predators including the Emperor penguin, Adélie penguin, and leopard seal. Ecosystems beneath shelves host microbial mats and chemosynthetic assemblages studied by expeditions like those organized by the Monterey Bay Aquarium Research Institute and the Alfred Wegener Institute.

Monitoring and Research Methods

Monitoring combines remote sensing from platforms such as Landsat 8, Sentinel-1, ICESat-2, CryoSat-2, and airborne campaigns like Operation IceBridge with in situ techniques including GPS deployments, hot-water drilling near grounding lines, and autonomous underwater vehicles built by institutions like WHOI and MBARI. Geophysical methods—seismic reflection, radar sounding pioneered at places like the Scott Polar Research Institute—resolve bed topography and basal conditions. Numerical models of ice–ocean interaction use frameworks developed by centers including NCAR, MPI for Meteorology, and the British Antarctic Survey.

Impacts on Global Sea Level and Climate

Loss or thinning of ice shelves affects global sea level primarily by modifying the rate of grounded-ice discharge from the Antarctic Ice Sheet; collapse can accelerate mass loss from basins such as the Amundsen Sea Embayment and potentially contribute to scenarios assessed by the IPCC AR6. Interactions with the Southern Ocean influence carbon uptake and regional climate feedbacks relevant to projections used by institutions such as the World Meteorological Organization and the United Nations Framework Convention on Climate Change.

Category:Ice shelves Category:Antarctica Category:Glaciology