The vast expanse of permanent ice that has characterized the Arctic Ocean for
millennia is fated to disappear far faster than anyone imagined, and will certainly
be gone before the century is out, says a NASA satellite study.
The startling survey shows that an area of ancient ice roughly as large as
Alberta is vanishing every decade as the climate warms.
Over the course of this survey, which ran from from 1978 to 2000, about 1.2
million square kilometers of supposedly permanent ice melted away -- more than
the total area of Ontario.
And the rate of the melt -- roughly 9 per cent a decade -- is speeding up,
said physicist Josefino Comiso, senior scientist at NASA's Goddard Space Flight
Center in Maryland and author of the study.
"This year we had the least amount of permanent ice cover ever observed,"
Dr. Comiso said.
His findings, published in Geophysical Research Letters, have caused a stir
because they show that the permanent ice cover is melting at roughly three times
the rate scientists had thought. If the melt keeps up at this rate, the permanent
ice cover at the top of the Earth will be gone before the end of this century.
But Dr. Comiso doubts the melt will be as slow as that. Instead, as the dense
ice disappears and exposes the ocean for the first time in millennia, the ocean
will pull in greater and greater amounts of solar energy. That is bound to speed
up the rate of the melt, Dr. Comiso said.
As well, satellite data show that the surface temperature of the permanent
ice is rising at the rate of 1.2 degrees C every decade, meaning that that could
force the ice to melt even faster.
The findings have huge implications for global climate patterns. Arctic snow
and ice play a key role in controlling the planet's temperature. They act as insulation,
keeping heat and moisture in the land and ocean and out of the atmosphere.
But once the ice and snow are gone, that dynamic will end and this will affect
climate all over the planet in ways scientists have not yet begun to fathom.
The Arctic itself, so long forsaken, is likely to become humid and warm. Animals
and fish that thrive on the permanent ice and snow -- polar bears, for example
-- are likely to die off, unable to survive the heat.
The cause of all this warmth, said Tom Agnew, a research meteorologist with
the Meteorology Service of Canada, is linked to the greenhouse-gas emissions that
humans are pumping into the atmosphere as they burn fossil fuels.
And while Dr. Comiso's findings show that the warming and melting cycle is
happening faster than expected, scientists have long predicted that the disrupted
climate eventually will cause the permanent Arctic ice to vanish. Instead, the
Arctic Ocean will partly freeze in the winter and thaw in the summer. Scientists
do not believe the thawing trend is reversible.
"This change is already taking effect," Mr. Agnew said. "The whole
system is very slow to start and also very slow to stop."
© 2002 Bell Globemedia Interactive Inc
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