http://www.commondreams.org/headlines01/0202-01.htm
Published on Friday,
February 2, 2001 by Inter Press Service
Major Glacier in Antarctica is Shrinking,
Say Scientists
by Danielle Knight
[ See
picture of the Antarctic Pine Island Glacier shrinking...
]
CAPTION:
"The huge but remote Antarctic Pine Island Glacier is thinning
at rates fast enough to raise global sea levels, British
researchers said on February 1, 2001. The glacier,
which is the largest glacier in West Antarctica, is seen
in this satellite photo taken January 3."
(National Snow and Ice Data Center via Reuters)
http://www.nsidc.org/
WASHINGTON - A major glacier formation in Antarctica is shrinking,
according to a new scientific report which is likely to heighten
concerns that global warming is causing the world's ice cover
to melt.
Scientists at the University
College London and the British
Antarctic Survey presented new evidence Thursday suggesting
that the West Antarctica's Pine Island Glacier is thinning
at a rate that, if continued, will have the glacier afloat
within 600 years.
Using satellite data, the scientists monitored the glacier
between 1992 and 1999 and found that this inland glacier
of the West Antarctic Ice Sheet lost about 31 cubic kilometres
of ice during this time. The study appeared Thursday in the
journal Science, a peer review publication.
The glacier is decreasing
by approximately four gigatons
per year, which is equivalent to approximately 0.01 millimetres
of sea level rise, says the report.
The Pine Island Glacier
is the largest of all the ice streams
that feed into the ocean and could therefore be a key indicator
of any larger changes afoot in the ice sheet's interior,
according to the researchers.
Scientists have taken
an interest in monitoring the
West Antarctic Ice Sheet because it contains enough
water to raise global sea level by approximately five
metres if the ice melted.
Andrew Shepherd, one
of the scientists involved in the
study, told IPS that there is no suggestion that the
findings are a sign of global warming. ''The cause of
the thinning/retreat still remains a mystery,'' he says.
But Shepherd says the
new data add ''weight to the argument
that changes at the ice sheet coastline, such as those
that may occur due to global warming, can affect the interior
of the ice sheet, where the majority of ice is stored''.
He says questions still
remain about the speed at which the
ice sheet is thinning. Scientists studying glaciers have
debated for many years whether or not a retreat of the
West Antarctic Ice Sheet would be an accelerating process.
''At present, our data
show that the retreat has been uniform
for the past eight years,'' says Shepherd.
If the retreat were
to accelerate, the resulting increase
in global sea levels could be far greater and sooner
than currently predicted, he says.
Other scientific studies
of the massive Antarctic ice cover,
which represents 91 percent of Earth's ice, have also concluded
that the ice is melting. But there is disagreement over how
quickly this is happening.
One study published
in Science in 1999 estimates that
the Western Antarctic Ice Sheet, the smaller of the
continent's two ice sheets, has retreated at an average
rate of 122 metres a year for the past 7,500 years and
is in no danger of collapse.
But other studies suggest
that the sheet may break more
abruptly if melting accelerates. They point to signs of
past collapse, as well as to fast-moving ice streams
within the sheet that could speed ice melt.
The new findings published
Thursday are likely to increase
concerns that global warming caused by the burning of oil,
gas and coal is having an impact on the Earth's ice cover.
At an international
conference in China on Jan. 22,
an international panel of hundreds of scientists from
more than 100 countries unanimously approved a report
that confirmed that the evidence for humanity's influences
on the global climate is stronger than ever.
The Intergovernmental
Panel on Climate Change predicts
an average warming of 1.4 to 5.8 degrees Celsius over
the coming century. Scientists expect this will cause
more frequent and intense storms, droughts and floods.
Sea levels are projected to rise by 0.09 to 0.88 metres
from 1990 to 2100, according to the report.
The Panel concludes
that it is very likely that snow cover
has decreased by about 10 percent since the late 1960s
in the mid- and high- latitudes of the Northern Hemisphere.
It also says it is likely that there has been a 40 percent
decline in Arctic sea-ice thickness during late summer
to early autumn in recent decades.
According to the Worldwatch
Institute, an environmental
think-tank here in Washington, scientists worldwide
are witnessing a dramatic melting at the planet's
coldest regions.
''From the polar regions
to high mountain glaciers,
Earth's ice cover is melting at an astonishing rate,''
says Lisa Mastny, a researcher at the Institute.
The World Glacier Monitoring
Service in Switzerland
says that the planet's glaciers are now shrinking
faster than they are growing and losses in 1997-1998
were ''extreme''.
Scientists predict
that up to a quarter of the global
mountain glacier mass could disappear by 2050, and
up to half by 2100 - leaving large patches only
in Alaska, Patagonia, and the Himalayas.
Mastny says the disappearance
of the Earth's ice cover
would significantly alter the global climate since
ice reflects large amounts of solar energy back into
space and helps cool the planet.
''When ice melts, however,
this exposes land and water
surfaces that retain heat - leading to even more melt
and creating a feedback loop that accelerates the
overall warming,'' she says.
Copyright 2001
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