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Topic: Antarctic ice sheet


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In the News (Fri 13 Nov 09)

  
 Antarctic Ice Shelves
Antarctic Glaciers Speed Up: Scientists at NSIDC have found that glaciers around the area of the Larsen B Ice Shelf accelerated immediately after it collapsed early in 2002, and are still speeding up.
Antarctic Ice Shelf Collapse Triggered by Warmer Summers: Recent work by scientists at NSIDC, NASA's Goddard Space Flight Center, and the University of Maryland, indicate that the shelves are particularly sensitive to climate change.
Ice Shelf Feels the Heat: "Warming waters may doom the Antarctic Peninsula's Larsen Ice Shelf, and other Antarctic ice shelves could be more endangered than had been thought, according to a paper published in the 31 October issue of Science." NSIDC researcher Ted Scambos is quoted in the paper.
nsidc.org /iceshelves   (536 words)

  
 Antarctic ice sheet decline startles scientists | Special reports | Guardian Unlimited
"The overall balance of the Antarctic ice is dependent on regional changes in the interior and those in the coastal areas," she said.
Previous studies have shown that the glaciers on the Antarctic peninsula, which sticks out from the West Antarctic ice sheet towards Argentina, began melting rapidly after the collapse of the Larsen B ice shelf in 2002.
The change in Antarctic ice mass is hard to measure because of the size and complexity of the ice sheets.
www.guardian.co.uk /antarctic/story/0,,1722581,00.html   (745 words)

  
 Antarctic ice sheet, 01-28-02
Antarctica's huge ice sheets are fed by snow falling in the interior of the continent.
The West Antarctic ice sheet is considered less stable than the larger East Antarctic ice sheet because much of it rests on land that is below sea level, and parts of it, called ice shelves, are floating on the sea.
Ice streams are fast-moving currents of ice within the ice sheet that carry large volumes of ice out onto the floating ice shelves.
www.ucsc.edu /currents/01-02/01-28/antarctica.html   (553 words)

  
 Antarctic ice sheet - Wikipedia, the free encyclopedia
The Antarctic ice sheet is the largest single mass of ice on Earth.
Around 90 percent of the fresh water on the Earth's surface is held in the ice sheet, an amount equivalent to 70 m of water in the world's oceans.
Ice enters the sheet through snow and frost and leaves by calving of icebergs and melting, usually at the base but also sometimes at the surface at warm sites
en.wikipedia.org /wiki/Antarctic_ice_sheet   (300 words)

  
 ScienceDaily: Antarctic Ice Sheet Losing Mass, Says University Of Colorado Study
Greenland Ice Sheet Still Losing Mass (September 29, 2006) -- Data gathered by a pair of NASA satellites orbiting Earth show Greenland continued to lose ice mass at a significant rate through April 2006, and that the rate of loss is accelerating, according to a...
Ice sheet -- An Ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometers (19,305 square miles).
Ice shelf -- An ice shelf is a thick, floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface, typically in Antarctica or Greenland.
www.sciencedaily.com /releases/2006/03/060302180504.htm   (2107 words)

  
 The Antarctic ice sheet and rising sea levels   (Site not responding. Last check: 2007-10-14)
The contribution to sea level rise of ice sheets in Antarctica and Greenland over this period is not well established and is subject of conflicting assessments, but it could account for around one third of the present rate of sea level rise which is ~2 mm per annum.
New snow is constantly added to the ice sheet as snowfall, and ice is constantly being lost through, direct melting into the seas, a small amount of runoff during periods of summer melt, and the calving of icebergs.
A decade of satellite measurements of the ice sheet surface in West Antarctica have shown that the portion of the ice sheet that drains into the Amundsen Sea is thinning at rates of several centimetres to several metres per year.
www.antarctica.ac.uk /Key_Topics/IceSheet_SeaLevel/index.html   (1176 words)

  
 Antarctic ice sheet is an 'awakened giant' - earth - 02 February 2005 - New Scientist
The massive west Antarctic ice sheet, previously assumed to be stable, is starting to collapse, scientists warned on Tuesday.
Glaciers on the Antarctic peninsula, which protrudes from the continent to the north, were already known to be retreating.
The last report of the Intergovernmental Panel on Climate Change, published in 2001, said that collapse of this ice sheet was unlikely during the 21st century.
www.newscientist.com /article.ns?id=dn6962   (561 words)

  
 Two New Lakes Found Beneath Antarctic Ice Sheet -- The Earth Institute at Columbia University   (Site not responding. Last check: 2007-10-14)
The shorelines of the lakes appeared in satellite images of the region as perturbations in the surface of the East Antarctic ice sheet.
In addition, because the ice is effectively floating on the surface of the lakes, the ice sheet exhibits slight depressions over the lakes that appear in radar and laser elevations.
Moreover, laser mapping of the ice sheet surface by NASA’s Ice Cloud and Land Elevation Satellite (ICESat) revealed that this water-ice boundary, or ceiling, is tilted.
www.earthinstitute.columbia.edu /news/2006/story01-26-06.html   (927 words)

  
 Fact Sheet: Ice Shelves
The weight of Antarctica's ice is so enormous that it has literally pressed the continent two thirds of a mile (one kilometer) into the earth.
During normal years, the total mass of calvings is an extremely small percentage of the ice cap, and the ice lost through calving equals the mass of snowfall on the continent.
Three more shelves, according to the National Snow and Ice Data Center, the National Oceanic and Atmospheric Administration, and the University of Colorado, have receded past a "point of no return." These three are the Larsen B, the Wilkins, and the George VI Ice Shelves.
www.asoc.org /general/iceshelve.htm   (995 words)

  
 Antarctic Ice Sheet Losing Mass, According To CU-Boulder Study | News Center | University of Colorado at Boulder
The estimated ice mass in Antarctica is equivalent to 0.4 millimeters of global sea rise annually, with a margin of error of 0.2 millimeters, according to the study.
While the CU researchers were able to differentiate between the East Antarctic ice sheet and West Antarctic ice sheet with GRACE, smaller, subtler changes occurring in coastal areas and even on individual glaciers are better measured with instruments like radar and altimeters, he said.
Ice shelves on the peninsula -- which has warmed by an average of 4.5 degrees Fahrenheit in the past 60 years -- have decreased by more than 5,200 square miles in the past three decades.
www.colorado.edu /news/releases/2006/86.html   (848 words)

  
 What Is Happening to the West Antarctic Ice Sheet?
The size of the ice sheet depends on snow accumulation, wind-driven reduction of glacial snow and ice, iceberg splitting, and subglacial melting and freezing.
Retreating West Antarctic ice exposed the floor of the Ross Sea to examination by marine geologists.
Ice coring at Siple Dome, begun in late 1997, is expected to contribute a detailed historical record of atmospheric chemistry and surface elevation.
www.agu.org /sci_soc/articles/bind.html   (2005 words)

  
 West Antarctic Ice Sheet - Wikipedia, the free encyclopedia
Away from the interior, the ice is channelled into anomalously fast-flowing ice streams, transporting ice from the center of the continent to the sea.
The inter-stream ridges are frozen to the bed while the bed beneath the ice streams consists of water-saturated clay.
In January 2006, in a UK government-commissioned report, the head of the British Antarctic Survey, Chris Rapley, warned that this huge west Antarctic ice sheet may be starting to disintegrate, an event that could raise sea levels by at least 16 feet.
en.wikipedia.org /wiki/West_Antarctic_Ice_Sheet   (1029 words)

  
 US NSF - OPP - ANT - Ice Sheets   (Site not responding. Last check: 2007-10-14)
The West Antarctic Ice Sheet contains more than 3.2 million cubic kilometers of ice, is the last ice sheet on Earth resting in a deep marine basin and is the most likely player in any future, rapid sea level rise.
Glacial geologic studies of land and marine-based deposits in the northern hemisphere, where most marine ice sheets once existed, have shown that this type of ice sheet is inherently unstable and vulnerable to rapid collapse.
Nearly 90 percent of the ice flowing across West Antarctica converges into ice streams that are the most dynamic, and perhaps unstable, components of the ice sheet.
www.nsf.gov /od/opp/antarct/science/icesheet.jsp   (389 words)

  
 Antarctic
The volume of the ice sheet is estimated to be 30 million cu.
The Antarctic ice sheet exerts one of the major controls on the climate of the southern hemisphere.
It is thus important to assess the stability of the cryosphere under a warming climate as noted by the Intergovernmental Panel on Climate Change, particularly as ice-core records have yielded evidence of a strong correlation between CO in the atmosphere and past temperatures.
www.aber.ac.uk /~glawww/antarctic.shtml   (2668 words)

  
 Global Sea Level Rise Forecast to Flood Low-Lying Coastlines
At the Royal Society in London, the Antarctic climate scientists are examining the latest evidence for climate change on the icy continent and its effects on the southern ice sheet, at a two day scientific meeting that winds up today.
Rignot is a principal investigator on NASA funded projects to study the mass balance of the Greenland and Antarctic ice sheets using radar interferometry combined with other methods; the interactions of ice shelves with the ocean; and the retreat of Patagonian glaciers.
Rignot presented data that shows ice shelves and glaciers in East Antarctica are thinning and losing mass, even though ice in that area is thought to be thickening overall due to increased amounts of snow and rainfall.
www.ens-newswire.com /ens/oct2005/2005-10-18-02.asp   (1076 words)

  
 Antarctic Ice Sheet Is Melting Rapidly (via CobWeb/3.1 planet03.csc.ncsu.edu)   (Site not responding. Last check: 2007-10-14)
The Antarctic ice sheet is losing as much as 36 cubic miles of ice a year in a trend that scientists link to global warming, according to a new paper that provides the first evidence that the sheet's total mass is shrinking significantly.
Richard Alley, a Pennsylvania State University glaciologist who has studied the Antarctic ice sheet but was not involved in the new research, said more research is needed to determine if the shrinkage is a long-term trend, because the new report is based on just three years of data.
Scientists have been debating whether the Antarctic ice sheet is expanding or shrinking overall, because the center of the sheet tends to gain mass through snowfall whereas the coastal regions are more vulnerable to melting.
www.washingtonpost.com.cob-web.org:8888 /wp-dyn/content/article/2006/03/02/AR2006030201712.html   (1012 words)

  
 CNN - NASA animates 20,000 years of Antarctic ice history - February 3, 1999
The majority of the west Antarctic ice sheet sits atop dry land, while the east Antarctic ice sheet is grounded below sea level.
Changes in the east Antarctic sheet would have little effect on sea levels since the ice displaces water, but a complete melt of west Antarctic ice would pour new water into the oceans.
Bindschadler said there is evidence that the west Antarctic ice sheet may have melted and reformed several times during the past 11 million years.
www.cnn.com /TECH/science/9902/03/antarctic.ice.sheet   (455 words)

  
 West Antarctic ice sheet is thickening - 17 January 2002 - New Scientist
The giant West Antarctic ice sheet, long the subject of warnings about its continuous melting and collapse, is actually getting thicker in parts.
That is a dramatic change in an ice sheet covering about a third of West Antarctica and that has retreated nearly 1300 kilometres since the end of the last ice age.
The ice is a kilometre thick, so "it would take thousands of years for surface temperature to affect the bed of the ice stream," he told New Scientist.
www.newscientist.com /article.ns?id=dn1806   (514 words)

  
 BBC News | SCI/TECH | Ice 'thickens' in West Antarctica   (Site not responding. Last check: 2007-10-14)
While the East Antarctic Ice Sheet is considered relatively safe, there have been fears that climate change could cause the WAIS to disintegrate, raising global sea levels by as much as five metres.
Most researchers are agreed that the West Antarctic Ice Sheet has been retreating over the last 10,000 years, but the new findings, published in the journal Science, could be evidence that that this trend is about to be reversed.
Most of the growth is on an ice sheet called ice Stream C. "The ice sheet has been retreating for the last few thousand years, but we think the end of this retreat has come," says Dr Joughin.
news.bbc.co.uk /1/hi/sci/tech/1766064.stm   (449 words)

  
 New Structure Found Deep Within West Antarctic Ice Sheet
Until now, scientific observations suggested that change to the West Antarctic Ice Sheet would be restricted to the edges implying that large-scale instability of the ice sheet is unlikely.
Ice sheets normally consist of flat layers of ice, so finding this huge fold was a complete surprise.
Its presence suggests that a few thousand years ago surface ice at the centre of the ice sheet was moving rapidly and being 'drawn down' towards the bottom of the ice sheet.
www.spacedaily.com /news/antarctic-04n.html   (453 words)

  
 Winter 2000 - Conway, Antarctic Ice Sheet
Using evidence gathered from raised beaches and radar imaging of subsurface ice structures to reconstruct historic changes, the scientists found the ice sheet has both thinned and decreased in area since the last glacial maximum 20,000 years ago.
Ice covering the region once was as much as a half-mile thick in places.
Floating ice now surrounds it, but reconstructions suggest that ice in the area of Roosevelt Island was about 1,600 feet thicker and was grounded during the last ice age.
www.artsci.washington.edu /newsletter/Winter00/Conway.htm   (387 words)

  
 BBC News | SCI/TECH | Antarctic ice sheet shrinks
A team of UK scientists has found evidence that a large area of Antarctic ice is shrinking.
The loss is being caused by changes in the fast-flowing Pine Island glacier (PIG), the largest glacier in West Antarctica, which carries ice from the interior to the sea.
Their data suggest that the thinning is the consequence of changes in the ice flow within the PIG, not of changes in snow accumulation.
news.bbc.co.uk /1/hi/sci/tech/1148183.stm   (642 words)

  
 Geodynamics - Antarctic ice sheet balance
Global sea level is affected by numerous factors, including human contributions from groundwater pumping and dam building, and the growth and decay of mountain glaciers and polar ice sheets.
An ice sheet that is gaining or losing mass would exert a changing force on the surface of the Earth, a force the Earth would respond to, in the same way that a spring scale responds to a weight.
The size and location of postglacial uplift in Antarctica depends on the timing, magnitude, and location of past Antarctic ice mass changes, all of which are rather poorly known, although Antarctica likely contributed 20-30 m to sea level rise since about 20,000 years ago.
gsc.nrcan.gc.ca /geodyn/antice_e.php   (468 words)

  
 NASA - NASA Mission Detects Significant Antarctic Ice Mass Loss
Because ice sheets are a large source of uncertainties in projections of sea level change, this represents a very important step toward more accurate prediction, and has important societal and economic impacts.
Grace is able to overcome these issues, surveying the entire ice sheet, and tracking the balance between mass changes in the interior and coastal areas.
The Antarctic mass loss findings were enabled by the ability of the identical twin Grace satellites to track minute changes in Earth's gravity field resulting from regional changes in planet mass distribution.
www.nasa.gov /vision/earth/lookingatearth/antarctica-20060302.html   (679 words)

  
 Satellite Images Show Antarctic Ice Sheet Losing Mass
The Antarctic ice sheet is losing mass, according to scientists using data from a pair of satellites orbiting the globe.
The Antarctic ice sheet is responsible for 90 percent of the world's ice.
As one satellite passes over an irregular mass on the ice sheet, it emits a slightly increased gravitational pull that slows it down slightly, and the deceleration is recorded by the other satellite.
www.voanews.com /english/2006-03-02-voa66.cfm   (513 words)

  
 Continents - Antarctica (via CobWeb/3.1 planet03.csc.ncsu.edu)   (Site not responding. Last check: 2007-10-14)
The Arctic is an oceanic basin lying beneath a thin layer of ice.
Antarctica is a land continent buried under a permanent ice sheet and surrounded by ocean.
The ice sheet that covers almost all of Antarctica is more than a mile thick.
www.uen.org.cob-web.org:8888 /utahlink/activities/view_activity.cgi?activity_id=3794   (1040 words)

  
 West Antarctic Ice Sheet Research   (Site not responding. Last check: 2007-10-14)
If the entire ice sheet was to collapse, sea level would rise 5-6 meters (about 20 feet).
Scientists believe that all marine-based ice sheets may be unstable; all other marine-based ice sheets have melted since the lastmajor ice age.
While there, we will be making three types of measurements to help us better understand the motion of the ice streams, their history, and what the conditions are like at the bottom of the ice sheet inthese areas.
itll.colorado.edu /ITLL/Templates/AntarcticResearch/Research/index.html   (452 words)

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