http://www.commondreams.org/headlines03/0310-07.htm
Published on Monday,
March 10, 2003 by the lndependent/UK
Polar Sea Ice Could be Gone by the End
of the Century
by Steve Connor
Much of the Earth's frozen north will have defrosted by the
end of the century, according to the latest study of the effect
of global warming on the Arctic.
New measurements of
the extent of sea ice around the entire
North Pole show that it has reduced by about 4 per cent a decade
on average over a 20-year period.
If the warming trend
continues, Arctic sea ice could, within
100 years, disappear almost completely during the summer months,
said Professor Ola Johannessen of the Nansen Environmental and
Remote Sensing Center in Bergen, Norway.
This would have a serious
impact on wildlife, such as the
estimated 22,000 polar bears living in the Arctic which need
abundant pack ice to hunt for seals during the summer.
Professor Johannessen
leads an international team of scientists
who measured sea ice across the entire Arctic region using a
phenomenon called elastic gravity waves - vibrations that can
be
used to estimate the thickness of the ice.
The findings, to be
published later this year, show the melting
of the Arctic ice has got considerably worse over the past 20
years.
By 2090, there could be 80 per cent less ice than there is today.
In addition, satellite
measurements have clearly shown that the
area of the Arctic Ocean covered by sea ice has shrunk on average
by about 8 per cent over the past quarter century, with the biggest
decline occurring in summer.
Professor Johannessen
said the marked and unprecedented thinning
of the Arctic sea ice took place in the last two decades of the
20th century. He believes it is largely the result of global warming
caused by man-made pollution.
"We believe there
are strong indications that neither the warming
trend nor the decrease of the sea-ice cover over the last two
decades
can be explained by natural processes alone," Professor Johannessen
said.
"[Two] climate
models both predict a dramatic decrease of the
ice cover, which could result in a nearly ice-free Arctic Ocean
during the summer months at the end of this century," he
said.
Previous attempts at
measuring the thickness of Arctic sea ice,
using declassified sonar data from military submarines, have
suggested that the ice has thinned by as much as 40 per cent
over the past 50 years.
However, Professor
Johannessen said that not all scientists
have agreed on the interpretation of these sonar measurements.
"The available sonar data remain inadequate for producing
a
reliable climatology of arctic ice thickness variability,"
he said.
Using elastic gravity
waves, the scientists were able to study
ice thickness over a wider area, as opposed to being restricted
to the routes followed by military submarines.
Conservationists fear
that melting sea ice in the Arctic
is forcing polar bears to swim for longer between floating
pack ice in search of seals, causing the loss of valuable
body fat.
A shortage of ice could
also affect hooded and harp seals
which rely on the ice to rear pups. A report by the International
Fund for Animal Welfare has warned the ice cover on Canada's
east coast - estimated to have fallen by up to 60 per cent
- is having a serious impact on seal populations.
© 2003 Independent
Digital (UK) Ltd
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