The last Sea Ice Outlook of this year has been published. The SIO is now organized by the Sea Ice Prediction Network (as part of the Arctic research program 'Study of Environmental Arctic Change', or SEARCH), and is a compilation of projections for the September 2014 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs (public outlooks).
Here's the summary for the August report:
Thank you to the groups that contributed to the August 2014 Outlook. We received 23 pan-Arctic contributions. Of the 23 contributions, some are unchanged from July. The median Outlook value for September extent is 5.0 million square kilometers with a quartile range from 4.58 to 5.22 million square kilometers. The overall range is between 4.0 and 5.6 million square kilometers. The median value for August is increased from the June and July values of 4.7 and 4.8 million square kilometers, respectively. This increase reflects the relatively slower decline in ice extent through August than what had been projected earlier. The overall range has narrowed since July, suggesting that the projections are tending to converge, as one would expect with a shorter forecast period. There were four regional Outlooks submitted with a fairly large range in both spatial extent and ice-free dates. There have not been any significant extreme weather events this summer as was seen during the record low years of 2007 and 2012. The more quiet conditions have likely played a role in the evolution of the sea ice extent this summer. While the extent is far from a record low, all contributions will put 2014 as one of the ten lowest September extents in the 36-year satellite record.
Read the entire report here.
And here's the figure showing all the projections (click for a larger version):
The September minimums for the last 9 years (in millions km2, found here):
Obviously the range has become smaller. June saw a range of 3.2 - 6.3, July had 3.2 - 5.9, and for August the range is 4.0 - 5.6 million km2. The CPOM (Schröder et al.) prediction, based on the fraction of melt pond cover in May, has hardly changed between the three SIOs. Which makes sense, of course. Their prediction might turn out a tad too high, but I still think they are on to something. When combined with other factors, like NH snow cover at the end of winter and initial state of the sea ice (thickness distribution etc), we might be able to tell in melting seasons to come whether there's a chance of new records towards the end of a melting season.
As far as submissions based on community voting goes, the WUWT prediction went down from 6.1 in June to 5.6 million km2 now. The poll on the Arctic Sea Ice Forum resulted in 4.0 in June, followed by 4.2 in July, and ending with 4.7 million km2 for the August poll. If we combine the results from both WUWT and ASIF polls, we get an average of 5.15, which is slightly above the median value of 5.0 million km2 from all SIO contributions. I've put the spreadsheet with the poll results on Google Drive, in case anyone would like to check for errors.
Like I wrote in the latest ASI update, it's very much neck and neck between 2014 and last year, so we'll have to wait and see where the average September sea ice extent ends up.