Some Antarctic ice form from bottom
Sat, 05 Mar 2011 18:45:39 GMT
An international scientific team has found that some Antarctic ice sheets are formed from the bottom up as a result of water re-freezing from below.
According to a report published in journal Science, snow is not the only element responsible for the formation of Antarctic ice sheets.
A group of scientists from six countries, who studied a jagged mountain range as high as the Alps in East Antarctica, found that almost a quarter of the ice sheet was formed by a thaw and re-freeze of water from beneath.
The ice below the surface flows into narrow, submerged valleys which are often melted due to high pressure and heat from the earth below. The thawed ice then re-freezes when it is forced up again.
"We usually think of ice sheets like cakes -- one layer at a time added from the top,” said lead author at Columbia University in New York Robin Bell in a statement.
“This is like someone injected a layer of frosting at the bottom -- a really thick layer," he added.
According to the report, about 24 percent of the ice around Dome A, a plateau the size of California in East Antarctica, was formed by re-frozen ice.
"In some places up to half the ice thickness has been added from below," the report said in reference to the ice above the invisible Gamburtsev Mountain range.
Experts hope to use the new finding in tackling the climate change issue as the South Pole contains enough ice to raise world sea levels by about 57 meters if it all melted.
It will also be helpful in understanding flows of Antarctic and Greenland ice sheets and possible responses to global warming.
The study gave "new understanding about ice sheet growth and movement that is essential for predicting how the ice sheet may change as the Earth's climate warms," said the British Antarctic Survey (BAS).
Some bulges which were detected by radars were so big that "we almost thought the equipment was broken," co-author Tom Jordan of BAS told Reuters.
Antarctic ice sheet were formed about 32 million years ago but some experts now believe that the oldest one only dated back to 1.4 million years old, Jordan said.