Although past studies have described the extent of multiyear ice -- ice that survives at least one melt season -- little is known about changes within the multiyear ice cover itself.

Using satellite-derived estimates of sea ice age and thickness, a team led by James Maslanik of the University of Colorado-Boulder constructed a thickness record for 1982 to the present. The researchers discovered 58 percent of multiyear ice consists of relatively young and thin 2- to 3-year-old ice, compared with 35 percent during the mid-1980s, with a nearly complete loss of the oldest, thickest ice.

The scientists said the decline helps expose more open water, which increases the absorption rate of solar energy. That not only helps explain recent large ice loss trends but also increase the potential of the current younger, thinner Arctic ice cover to rapidly melt.

The research, which included National Aeronautics and Space Administration scientists appears, in the journal Geophysical Research Letters.