GREENBELT, Md., March 1 (UPI) -- The oldest and thickest arctic sea ice is disappearing faster than younger and thinner ice at the edges of the Arctic Ocean's floating ice cap, NASA says.
Normally the thicker ice, known as multiyear ice, survives through the summer melt season while young ice that has formed over winter quickly melts again.
The rapid disappearance of older ice is making arctic sea ice even more vulnerable to further decline in the summer, researcher Joey Comiso at NASA's Goddard Space Flight Center in Greenbelt, Md., said.
The NASA study published in Journal of Climate examined how multiyear ice -- ice that has survived through at least two summers -- has diminished with each passing winter over the last three decades.
Multiyear ice "extent" is diminishing at a rate of 15.1 percent per decade, the researchers found.
"The average thickness of the arctic sea ice cover is declining because it is rapidly losing its thick component, the multiyear ice," Comiso said. "At the same time, the surface temperature in the arctic is going up, which results in a shorter ice-forming season.
"It would take a persistent cold spell for most multiyear sea ice and other ice types to grow thick enough in the winter to survive the summer melt season and reverse the trend."