Ice Shelf

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ice shelf

[′īs ‚shelf]
(oceanography)
A thick sheet of ice with a fairly level or undulating surface, formed along a polar coast and in shallow bays and inlets, fastened to the shore along one side but mostly afloat and nourished by annual accumulation of snow and by the seaward extension of land glaciers.

Ice Shelf

 

a glacier that is floating or partially resting on the bottom and flowing from the shore into the sea in the form of a plate that diminishes in thickness toward the edge and terminates in a cliff.

The ice shelf is a continuation of land ice sheets. More rarely, it is formed by the accumulation of snow on sea ice and by the cementing together of accumulations of icebergs by snow and ice. Ice shelves are found almost exclusively in Antarctica. Their total area is 1,460,000 sq km; the volume is about 0.6 million cu km; and the thickness varies from 200–1,300 m at the land edge to 50–400 m at the sea edge. The accumulation area usually encompasses the entire upper surface and the coastal section of the lower surface where ice forms; in the marginal zone the ice melts on the bottom (up to 1 m per year). A large part of the loss occurs from the breaking off of icebergs (a volume at times of thousands of cu km). The rate of movement of the ice shelf, which increases toward the edge, varies from 300–800 m to 1,800 m and more per year. (The largest ice shelf is the Ross Ice Shelf.)

REFERENCES

Shumskii, P. A. “Oledenenie Antarktidy.” In the collection Osnovnye itogi izucheniia Antarktiki za 10 let. Moscow, 1967.
Atlas Antarktiki, vol. 2. Leningrad, 1969.
References in periodicals archive ?
While the melting or breakup of floating ice shelves does not directly raise sea level, ice shelves do have a door stop effect, said the study published in the journal Nature Geoscience.
Researchers have drilled holes through ice shelves and dropped instruments into the frigid water beneath, but even that's been done at fewer than 20 sites in Antarctica in the past half-century, says Keith W.
What the team observed was that during the summer, relatively warm surface waters are pushed beneath the ice shelves by strong wind-driven currents.
Washington, Feb 23 (ANI): A new research by US Geological Survey (USGS) has determined that ice shelves are retreating in the southern section of the Antarctic Peninsula due to climate change, which could result in glacier retreat and sea-level rise if warming continues.
Infragravity waves may produce ice-shelf fractures that enable abrupt disintegration of ice shelves that are also affected by strong surface melting," according to the researchers.
At present, there is little change in ice shelves and coastal glaciers away from the Antarctic Peninsula, but if more Antarctic ice is lost as a result of climate change then these new blooms have the potential to be a significant biological sink for carbon," said Professor Peck.
If the trend continues, ice shelves closer to the pole will disintegrate, they predict.
Loss of the Antarctic ice shelves, which extend from the southern polar land mass over the underwater continental shelf, are likely to result in the glaciers behind them flowing more rapidly into the sea.
Two other ice shelves in the area, Larsen A and B, have broken up and disappeared since 1995.
Glaciologists from Aberystwyth University will be flying to Antarctica at the beginning of next month to study the phenomenon of large lakes that have been forming on the surface of ice shelves
Ice shelves line 45 percent of Antarctica's coast, helping stem the flow of the continent's ice sheets and glaciers into the ocean.
Spence explained the warm water could cause the melting of ice shelves around Antarctica, including the ice sheets.