Odd stuff at RealClimate: Arctic has always shown large internal variability; sea ice volume data is much more useful than extent; we don't have much data on sea ice volume

RealClimate: An icy "retreat"

A single regional cold spell has not a lot to do with climate – let alone with global climate...the Arctic has always shown large internal variability...For the measurement of this extent, it doesn’t matter at all how thick the ice is: any ice, however thin, contributes to sea-ice extent. Therefore, only considering a possible “recovery” of just the extent of Arctic sea ice always remains somewhat superficial, since sea-ice extent contains no information on the thickness of the ice. A much more useful measure for the state of Arctic sea ice is therefore the total sea-ice volume. However, for its estimation one additionally requires information on the overall distribution of ice thickness, which we have not been able to measure routinely in the past. While this will hopefully change in the future because of the successful launch of the Cryosat 2 satellite a couple of weeks ago, at the moment we unfortunately must rely on judging the current state of the Arctic sea-ice cover mostly by its extent...if the summer should turn out to be colder than during the previous years, a sea-ice minimum similar to that observed in 2009 would not be too surprising