Arctic ice 'shrinking rapidly'
Ice is declining in the Arctic
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Tuesday, 01, May 2007 11:48
Arctic sea ice is shrinking more rapidly than scientists had predicted, a new study claims.
The decline is so great that it surpasses the rates predicted by any of the 18 computer models used by the Intergovernmental Panel on Climate Change (IPCC) in preparing its 2007 assessments.
Models of climate change simulated a loss in September ice cover of 2.5 percent per decade from 1953 to 2006.
The fastest decline predicted by a model was 5.4 per cent per decade.
But scientists claim information from aircraft and ship reports along with more recent satellite measurements show that the September ice actually declined at a rate of about 7.8 percent per decade during the 1953-2006 period.
Julienne Stroeve of Colorado's National Snow and Ice Data Centre said: "This suggests that current model projections may in fact provide a conservative estimate of future Arctic change, and that the summer Arctic sea ice may disappear considerably earlier than IPCC projections."
National Centre for Atmospheric Research (NCAR) scientist Marika Holland, one of the study's co-authors, added: "While the ice is disappearing faster than the computer models indicate, both observations and the models point in the same direction: the Arctic is losing ice at an increasingly rapid pace and the impact of greenhouse gases is growing."
The study's authors conclude that due to the discrepancies between the models' predictions and actual rates, the shrinking of summertime ice is about 30 years ahead of the climate model predictions.
As a result the Arctic could be seasonally free of sea ice earlier than the IPCC's predicted time of between 2050 and 2100.
The research is published in today's online edition of Geophysical Research Letters.