From the National Geographic article:

This year's ice cover was not a record low, but it did continue a
dubious streak. The past six years (2004-09) have seen the least
Arctic ice at the time of maximum cover, in winter, since satellite
records began in 1979.

[ . . . ]

"From a record low last year of 5 percent or less [it was] back where
it used to be, in the 10 to 15 percent range," Meier explained.

But he remains skeptical that enough of the younger ice could survive
coming summers to make up for losses of older ice.

"This is not something that can be done in a couple of cold winters.
We're way below where we used to be, and it would take many years to
get back to where we were in the 1980s."

[ . . . ]

Comprehensive Arctic satellite data stretches back some three decades,
though some regions near Alaska and Siberia have been otherwise
closely monitored since the 1950s.

Data from the rest of the 20th century, and previous centuries, are
far less comprehensive. But scientists do have reports of ice cover
from shipping records and other historic documents.

"It's been a long time since we've seen so much open water," said Ron
Lindsay of the University of Washington's Polar Science Center.

"It really is unprecedented, what we've been seeing, for centuries and
maybe thousands of years."

http://news.nationalgeographic.com/n...e-younger.html