Melts At Record Level
By David Adam
30 September, 2005
Global warming in
the Arctic could be soaring out of control, scientists warned yesterday
as new figures revealed that melting of sea ice in the region has accelerated
to record levels.
Experts at the US
National Snow and Data Centre in Colorado fear the region is locked
into a destructive cycle with warmer air melting more ice, which in
turn warms the air further. Satellite pictures show that the extent
of Arctic sea ice this month dipped some 20% below the long term average
for September - melting an extra 500,000 square miles, or an area twice
the size of Texas. If current trends continue, the summertime Arctic
Ocean will be completely ice-free well before the end of this century.
Ted Scambos, lead
scientist at the Colorado centre, said melting sea ice accelerates warming
because dark-coloured water absorbs heat from the sun that was previously
reflected back into space by white ice. "Feedbacks in the system
are starting to take hold. We could see changes in Arctic ice happening
much sooner than we thought and that is important because without the
ice cover over the Arctic Ocean we have to expect big changes in Earth's
The Arctic sea ice
cover reaches its minimum extent each September at the end of the summer
melting season. On September 21 the mean sea ice extent dropped to 2.05m
square miles, the lowest on record. This is the fourth consecutive year
that melting has been greater than average and it pushed the overall
decline in sea ice per decade to 8%, up from 6.5% in 2001.
Walt Meier, also
at the Colorado centre, said: "Having four years in a row with
such low ice extents has never been seen before in the satellite record.
It clearly indicates a downward trend, not just a short term anomaly."
Surface air temperatures
across most of the Arctic Ocean have been 2-3C higher on average this
year than from 1955 to 2004.
The notorious northwest
passage through the Canadian Arctic from Europe to Asia - where entire
expeditions were lost in earlier centuries as their crews battled thick
ice and bitter cold - was completely open this summer, except for a
60 mile swath of scattered ice floes. The northeast passage, north of
the Siberian coast, has been ice free since August 15.
in the Arctic has begun much earlier in recent years; this year it started
17 days earlier than expected. The winter rebound of ice, where sea
water refreezes, has also been affected. Last winter's recovery was
the smallest on record and the peak Arctic ice cover failed to match
the previous year's level.
The decline threatens
wildlife in the region, including polar bears that spend the summer
on land before returning to the ice when it reforms in winter. It is
also the latest in a series of discoveries that have raised the spectre
of environmental tipping points: critical thresholds beyond which the
climate would be unable to recover. Duncan Wingham, an Arctic ice expert
at University College London, said: "One has to be a bit careful
with the notion of a tipping point because the situation is recoverable.
"If you drop
the atmospheric temperature then the ice will come back again. There
is a distinction between that and the Greenland ice sheet, which wouldn't
reform because the modern climate is far too warm."
Prof Wingham is
head of a European project that will launch a new satellite next weekend
to monitor the thickness of the Arctic sea ice - and to check on the
role global warming plays in its decline. Some had suggested that a
periodic weather system called the Arctic oscillation had blown thick
sea ice from the Arctic during the 1990s, leaving thin ice more liable
to melting in its place.
© Guardian Newspapers Limited 2005