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Antarctic glacier - Source: Reuters
A glacier in Greenland slides up to 220% faster towards the sea
in summer than in winter and global warming could mean a wider
acceleration that would raise sea levels, according to a study
published.
A group of experts led by Ian Bartholomew at Edinburgh University
in Scotland said the variability was much stronger than earlier
observations of glacier movement in Greenland.
The study, published in the journal Nature Geoscience, is a new
piece of a puzzle to understand the world's second biggest ice
sheet behind Antarctica.
Greenland has enough ice to raise world sea levels by about
seven metres if it all melted.
The study said GPS satellite measurements of the glacier in
south-west Greenland, up to 35 km inland and at altitudes of up to
1,095 metres, showed that the ice in some places slid at 300 metres
per year at peak summer rates.
"Our measurements reveal substantial increases in ice velocity
during summer, up to 220% above winter background values," it
said.
The scientists said that the summer slide might be linked to melt
water seeping under the ice. It did not speculate if the change in
speed between summer and winter was part of natural shifts or was
influenced by a changing climate.
But they wrote: "In a warming climate, with longer and more intense
summer melt seasons, we would expect that water will reach the bed
farther inland and a larger portion of the ice sheet will
experience summer velocity changes."
The United Nations panel of climate experts said in 2007 that
global warming was unequivocal and that it was more than 90%
certain that most warming in the past half century was caused by
human activities led by the burning of fossil fuels.
The UN panel has come under fire this year after officials said its
latest report in 2007 exaggerated the pace of melt of Himalayan
glaciers by saying they might all disappear by 2035.
More than 250 members of the US National Academy of Sciences
defended climate change research against political assaults, and
said that any delay in tackling global warming heightens the risk
of a planet-wide catastrophe.
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