The below average winter ice cover follows 2012's record-low summer ice extent. Photo: NASA
The Arctic sea ice reached its maximum winter extent last month -- and NASA says it was the fifth lowest on record.
At a little over 15 million square kilometres, the winter coverage peak was 374,000 square kilometres below the 35-year average.
That's following on the summer of 2012, which boasted the lowest-ever Arctic ice levels ... about 3.4 million square kilometres.
Joey Cosimo, principal investigator of NASA's Cryospheric Sciences Program, says since much of the Arctic is in total or near-total darkness during the winter months, most of the solar radiation that acts on it is infrared or long-wave, which he says is associated with greenhouse warming effects.
"A decline in sea ice cover in winter is thus a manifestation of the effect of the increasing greenhouse gases on sea ice," he says.
But Cosimo says the winter maximum doesn't necessarily give any indication on how the summer Arctic ice might fare.
"It isn't as simple as that," he says. "You can have a lot of other forces that affect the ice cover in the summer, like the strong storm we got in August last year, which split a huge segment of ice that then got transported south to warmer waters, where it melted."
NASA says nine of the last 10 record low winter ice maximums occurred within the last decade.