NASA: Arctic Sea ice still at risk

Washington -- The U.S. space agency said updated satellite data show Arctic Sea ice has increased in some colder-than-average areas but continues to decline elsewhere.

National Aeronautics and Space Administration scientists said the increased area of sea ice this winter is due to recent weather conditions, while the decline in perennial ice reflects the longer-term warming climate trend.

Perennial sea ice is the long-lived, year-round layer of ice that remains even when the surrounding short-lived seasonal sea ice melts during the summer. NASA said it is that perennial sea ice, left from the summer melt period, that has been rapidly declining from year to year.

The latest satellite data show where perennial ice used to cover 50 percent to 60 percent of the Arctic. This year it covers less than 30 percent. Very old ice that remains in the Arctic for at least six years comprised more than 20 percent of the Arctic area in the mid-to-late 1980s, but this winter it decreased to only 6 percent.

Researchers said the Arctic ice cover is much thinner overall and thus in a more vulnerable state heading into the summer melt season.

Copyright 2008 by United Press International.