It really wasn’t a trend-setting year for Arctic sea ice extent. Yes, Arctic ice did set a new all-time low according to the most precise measure of ice extent, and it set record lows for calendar months along the way, but the new ice extent records were barely below previous marks from the last four years. What is really noteworthy about this summer’s Arctic sea ice is not the extent, but how broken up it was. Satellite photos from the densest areas of Arctic ice this summer showed virtually all of it broken into 1- and 2-kilometer pieces with gaps of hundreds of meters between. I didn’t see any areas where ice held together in solid blocks that extended for miles in all directions. The textbook picture of solid ice largely held true until this summer, but when it broke down, the breakup extended all the way to the North Pole.
Even as the gaps filled in with new ice fragments in September, the southern edges of the ice continued to retreat. As of today, open water stretches as far north as 83° north latitude, 800 kilometers from the North Pole. Svalbard, which by historical standards ought to be connected at its north and east coasts to a near-solid polar ice mass, still has 1,000 kilometers of open Arctic Ocean waters north of it. So even if the ice in 2011 didn’t convincingly break the 2007 extent minimum record, it gives every indication of being thinner and more fragile than we have ever seen.
As I have mentioned before, this was a spring and summer of unremarkable Arctic Ocean weather. Ice observers now believe calm conditions in March, cloud cover in July, and December and January snows protect the ice cover from melting. If we were to ever get a year with the opposite conditions in these three seasons, a series of new record lows would be virtually assured.