Arctic ice 'shrinking fast'
2006-09-14 14:16
Paris - Year-round sea ice in the Arctic shrank by one seventh between 2004 and 2005, a dramatic event that could herald a vicious regional circle of warming, a new study says.
Perennial sea ice is ice that floats on the sea and remains there year-round and can be up to three metres thick.
It is different from "seasonal" ice, which is only between 30 centimetres to two metres thick and survives for only one winter before melting in summer.
The study, published in the latest issue of Geophysical Research Letters, a US journal, said ice coverage of the Arctic in September 2005 was the lowest recorded in terms of area since 1978, when satellite monitoring began.
The loss of perennial ice in the East Arctic Ocean, which is above Europe and Asia, reached 50% between 2004 and 2005, as some of the ice moved to the West Arctic Ocean, above North America.
Overall, about 720 000 square kilometres - an area the size of Texas - was lost from one year to the next.
The scientists, who used data from Nasa's QuikSCAT satellite, took further measurements in April 2006, and found that perennial ice extent in the East Arctic Ocean had depleted by 70% compared with October 2005.
If the ice retreat continues, the impact will be profound, the study said.
Ice, being white, reflects the Sun's rays. Less ice therefore means the sea warms, which in turn accelerates the shrinkage.
In addition, marine animals, such as polar bears and seals, whose life cycle depends on the ice, could be badly affected.