Arctic re-freeze officially began on September 19th. Now, twelve days later, all monitors are still showing sea ice area and extent below the record low set in 2007. Overall, departures from the 2007 minimum are still in the range of 150,000 to 250,000 kilometers. At the current pace of refreeze, it will still be a few more days before the lowest extent for 2007 is exceeded in some monitors.
Departures from the ‘average’ sea ice area for the period of 1979-2008 are still very high at 2.48 million square kilometers below the ‘norm.’ Departures from values seen during the 1980s, however, are much greater. In the range of 3.8 million square kilometers below values for the same date. This is a loss of 58% of sea ice for the same period since the 1980s.
As for sea ice extent, you can see from the graph below that we are also currently in the range of about 60% less than the 1980s for the September minimum. Current values tend to be holding this difference. As we go forward into winter we would expect at least some of this gap to erode. We’ll have to see by how much as the season progresses.
(image credit: Neven)
All current measurements for sea ice are showing record low values for this date in history and, as noted above, current values are still below all time records for every year except for 2012.
We are still waiting on a final sea ice volume measurement from PIOMAS to determine yearly volume losses for 2012. So far, losses are in the 400 cubic kilometer range. But this official measurement is as of August and a final number for September is yet to be produced. An excellent visual of sea ice volume losses through August 25, 2012, provided by L. Hamilton, can be seen below.