- New scientific evidence reveals that the Antarctic ice
shelf is at more risk of melting than previously calculated.
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- Rising summer temperatures rather than overall mean annual
temperatures are exposed as the biggest threat to the polar ice.
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- Scientists warn that the vast ice shelves are "just
a few degrees" away from a potentially catastrophic meltdown.
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- If the ice melts, the rush of billions of gallons of
water into the oceans will lead to rising sea levels, affect global weather
systems and, ultimately, adversely impact on wildlife and mankind.
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- While some areas of the Antarctic have warmed by as much
as 2.5C in the past 50 years, few records have been kept of seasonal temperatures
over ice shelves. Researchers from NASA and teams of university scientists
report in the latest issue of the Journal of Glaciology that warmer surface
temperatures over just a few months in the Antarctic can splinter an ice
shelf and prime it for a major collapse.
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- Tell-tale signs of melt water on the ice surface were
studied using a sophisticated computer simulation of the motions and forces
within an ice shelf. The scientists demonstrated that added pressure from
surface water filling crevasses only a few feet deep can crack through
the ice entirely. They warn that this process can be expected to become
more widespread if Antarctic summer temperatures continue to increase.
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- Christina Hulbe, of the University of Maryland and NASA's
Goddard Earth Science & Technology Centre, said: "The importance
of melt water implies that ice shelf stability may not be limited by the
mean annual temperature, as has long been thought, but by the mean summer
temperature. As the mean summer temperature exceeds 0 degrees Celsius,
surface melting is likely to promote ice-shelf retreat."
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- Ted Scambos, of the National Snow and Ice Data Centre
at the University of Colorado, added: "This result implies that other
ice shelves are closer to the breaking point than we previously thought."
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- Further research is being carried out by the team that
focussed on the Larsen Ice Shelf on the Antarctic Peninsula, which experienced
major retreats in 1995 and 1998.
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