NASA examines the reasons behind the record low Arctic ice cover
From Nasa news, Oct 1. Contact information at end of article.
NASA EXAMINES ARCTIC SEA ICE CHANGES LEADING TO RECORD LOW IN 2007
A new NASA-led study found a 23-percent loss in the extent of the Arctic’s thick, year-round sea ice cover during the past two winters. This drastic reduction of perennial winter sea ice is the primary cause of this summer’s fastest-ever sea ice retreat on record and subsequent smallest-ever extent of total Arctic coverage.
A team led by Son Nghiem of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., studied trends in Arctic perennial ice cover by combining data from NASA’s Quick Scatterometer (QuikScat) satellite with a computing model based on observations of sea ice drift from the International Arctic Buoy Programme. QuikScat can identify and map different classes of sea ice, including older, thicker perennial ice and younger, thinner seasonal ice. Between winter 2005 and winter 2007, the perennial ice shrunk by an area the size of Texas and California combined. This severe loss continues a trend of rapid decreases in perennial ice extent in this decade. Study results will be published Oct. 4 in the journal Geophysical Research Letters.
The scientists observed less perennial ice cover in March 2007 than ever before, with the thick ice confined to the Arctic Ocean north of Canada. Consequently, the Arctic Ocean was dominated by thinner seasonal ice that melts faster. This ice is more easily compressed and responds more quickly to being pushed out of the Arctic by winds. Those conditions facilitated the ice loss, leading to this year’s record low amount of total Arctic sea ice.