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solonavi 12 December 2006 Climate, General, Global Warming 186 views No Comment Print This Post  Email This Post

bbc

The Arctic may be close to a tipping point that sees all-year-round ice disappear very rapidly in the next few decades, US scientists have warned.

The latest data presented at the American Geophysical Union Fall Meeting suggests the ice is no longer showing a robust recovery from the summer melt.

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The sea ice reached its minimum extent this year on 14 September, making 2006 the fourth lowest on record in 29 years of satellite record-keeping and just shy of the all time minimum of 2005.

Dr Serreze’s concern was underlined by new computer modelling which concludes that the Arctic may be free of all summer ice by as early as 2040.

The new study, by a team of scientists from the National Center for Atmospheric Research (NCAR), the University of Washington, and McGill University, found that the ice system could be being weakened to such a degree by global warming that it soon accelerates its own decline.

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In one of the model’s simulations, the September ice was seen to shrink from about 5.9 million sq km (2.3 million sq miles) to 1.9 million sq km (770,000 square miles) in just a 10-year period.

By 2040, only a small amount of perennial sea ice remained along the north coasts of Greenland and Canada, while most of the Arctic basin was ice-free in September.

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The average sea ice extent for the entire month of September this year was 5.9 million sq km (2.3 million sq miles). Including 2006, the September rate of sea ice decline is now approximately -8.59% per decade, or 60,421 sq km (23,328 sq miles) per year.

At that rate, without the acceleration seen in the new modelling, the Arctic Ocean would have no ice in September by the year 2060.

In one NCAR simulation, September ice was seen to shrink from about 5.9 million sq km to 1.9 million sq km in just a 10-year period. By 2040, only a small amount of perennial sea ice remained along the north coasts of Greenland and Canada, while most of the Arctic basin was ice-free in September.