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 ?
Co-author Dr Poul Christoffersen, from Cambridge University's Scott Polar Research Institute, pointed out that collapsing ice shelves can double or triple the speed at which glaciers flow to the ocean.
South African oceanographers from the University of Cape Town and Nelson Mandela University will take measurements of the salinity and temperature of the water column adjacent to the floating ice shelves to assess the modern oceanographic setting and melt rate, while researchers from the Nekton Oxford Deep Ocean Research Institute will sample deep sea marine life, and perhaps discover species new to science.
The hum is too low in frequency to be audible to human ears, but the new findings suggest scientists could use seismic stations to continuously monitor the conditions on ice shelves in near real-time.
Since ice shelves are already floating, their melting doesn't cause any change to global sea levels.
"It is a sign that ice shelves are more and more vulnerable," she told AFP.
"The data allows us to create models to make more long-term forecasts for even bigger ice shelves."
Ice shelves are the floating extensions of the continent's massive land-based ice sheets.
NASA and researchers in Europe separately report evidence of accelerated melting and destabilization of Antarctic ice shelves
" While melting ice shelves do not themselves cause sea levels to rise, they have an indirect ect, the scientists pointed out.
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.
Ice shelves line 45 percent of Antarctica's coast, helping stem the flow of the continent's ice sheets and glaciers into the ocean.