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Arctic ponds 'drying up'
03/07/2007 07:54 - (SA)
Chicago - Ancient ponds in the Arctic are
drying up during the polar summer as warmer temperatures
evaporate shallow bodies of water, Canadian researchers said on
Monday.
They said the evaporation of these ponds - some of which
have been around for thousands of years - illustrates the
rapid effects of global warming, threatening bird habitats and
breeding grounds and reducing drinking water for animals.
For the past 24 years, researchers at the University of
Alberta in Edmonton and Queen's University in Kingston,
Ontario, have been tracking ponds at Cape Herschel, located on
the east coast of Ellesmere Island in Nunavut, formerly the
Northwest Territories of Canada.
Last year, when they went back to check, some of these
6 000-year-old ponds had vanished.
"We were surprised. We arrived in early to mid-July and the
ponds we had been monitoring were dry. Some of them had dried
up completely. Some were just about to lose the last remaining
centimetres of water," said Marianne Douglas, director of the
Canadian Circumpolar Institute at the University of Alberta.
"It's really interesting to see how quickly it is
happening. We could see this trend had started a while ago but
at no time did we expect it to accelerate," said Douglas, whose
work appears in the journal Proceedings of the National Academy
of Sciences.
Douglas said a study of the fossilised sediments in these
pools of water - which are less than two metres deep
- showed climate changes beginning as long as 150 years ago.
The researchers had thought these ponds were permanent.
But change has come rapidly.
"It is a bit of a tipping point. We don't know how far this
warming or drying will go," she said.
Douglas, John Smol of Queen's University and colleagues
took water samples to measure the concentration of minerals and
sediments in the water. They compared it to data from the 1980s
and found a significant change.
Evaporation had made the sediments much more concentrated.
They also discovered that ponds that formerly remained
frozen until mid-July were free of ice as early as late May.
"No small wonder that we are seeing evaporation occurring,"
she said. "An extra month is tremendously long up there where
the growing season is so short."
The changes will have significant impact on the birds and
animals that rely on these sources of fresh water to survive
and breed.
"The ecological ramifications of these changes ... will
cascade throughout the Arctic ecosystem. ... Lower water levels
will have many indirect environmental effects, such as further
concentration of pollutants," they wrote.
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