Data from the US National Snow and Ice Data Center (NSIDC) shows that the year began with ice covering a larger area than at the beginning of 2007.
But now it is down to levels seen last June, at the beginning of a summer that broke records for sea ice loss.
Scientists on the project say that much of the ice is so thin that it melts easily, and the Arctic may be ice-free in summer within five to 10 years.
"We had a bit more ice in the winter, although we were still way below the long-term average," said Julienne Stroeve from NSIDC in Boulder, Colorado.
"So we had a partial recovery. But the real issue is that most of the pack ice has become really thin, and if we have a regular summer now, it can just melt away," she told BBC News.
In March, Nasa reported that the area covered by sea ice was slightly larger than in 2007, but much of it consisted of thin floes that had formed during the previous winter. These are much less robust than thicker, less saline floes that have already survived for several years.
A few years ago, scientists were predicting ice-free Arctic summers by about 2080.
Then computer models started projecting earlier dates, around 2030 to 2050.
Then came the 2007 summer that saw Arctic sea ice shrink to the smallest extent ever recorded, down to 4.2 million sq km from 7.8 million sq km in 1980.
By the end of last year, one research group was forecasting ice-free summers by 2013.
"I think we're going to beat last year's record melt, though I'd love to be wrong," said Dr Stroeve.
"If we do, then I don't think 2013 is far off any more. If what we think is going to happen does happen, then it'll be within a decade anyway."