A first, very crude, attempt to analyse this strange year.
And a rather long tale, I fear...)
I compared high concentration (UB +90%)/low concentration area 2013 to 2012 for 26 August.
On high concentration: ’12 had 2,1 mkm2 against ’13 2,7 mkm2 (Note: ’13 also has 0,7 mkm2 HC ice on the far Siberian side of the CAB. I’ll get to that later…). This is the core of the sea ice cover, in which the remaining “mesh-pack” is embedded. After checking my CAD work, I see not much difference in the area covered by the “mesh pack” in both years, about 1,1 mkm2, although the regional spread of it has changed considerably.
On the low concentration side, ’12 had 0,9 mkm2 against 2,0 mkm2 for ’13 (including the 0,7 mkm2 Siberian side HC swath).
The important difference in ‘13 is the 0,6 mkm2 larger HC area in the core. This difference is located on the Beaufort side of the CAB. It fits well with the area that’s been about an average of 3 dC colder during the May-August period than last year.
The most poignant difference is the 1,1 mkm2 larger LC area stretching way into the ESAS. That part of the Arctic was colder than last year, but much less pronounced than near the CAA, about 0,5dC.
The only stretch with less ice than last year is the Atlantic side. Dismissing the bunch of stubborn fast ice SW of Severnaya Zemlya in the Kara Sea, the difference is 250K, partly in the EGS, most in the Barentsz sector of the CAB. That fits with the vast area of +2dC warmer temps than last year over the Barentsz and Norwegian Seas.
What happened? The mobility of the pack in winter pushed vast parts of the “mesh pack” into the Beaufort sector. Likewise, the remaining HC ice of ’12 in the Laptev sector (the’Goat’s Head, FI) rotated back into the Greenland sector, while the Fram express never really picked up except for first- and second year ice that was over the Nansen Basin late winter/spring.
In the same rotation, some second- and good new FYI headed for the ESAS sector.
In a way, the reorganisation at work in the atmosphere over the Northern Hemisphere helped to set up a circulation that kept ice within the CAB and suppressed summer warming. A strong, persistent low over the American CAB side kept winds defending against much warming from the South. It is a feature related to the reorganisation I mentioned, as it went all the way up to the stratosphere. All Geopotential levels were anomalously low this summer over a tight area. This created it’s own Jet on 200Mb, while the Polar Jet, normally located over 55dN, almost faded out.
On the sideline, in summer the Jet usually is less strong than during winter. But this summer really stands out.
Based on the pattern, crudely described above, I see what happened not as a statistical ‘revert’ to normal, or rebound or whatever you can call the ups-and-downs in a range. I see this as a stage in a dynamical whirl of change. I think it is important to approach what’s going on like that. Whether the statistical or dynamical approach is taken, the short term effects are more or less the same. We see a possible range of ‘long-tail’ years rising. If so, it may be time to express some reconciliation to the pro’s and modellers. It is very possible the state of Arctic sea ice and the trend in GHG forcing will be more in line. At least, for some years.
That ASI won’t be an immediate “canary-in-the-coalmine” doesn’t mean the whirl of change will be less severe in other parts of our World.
In a way, that’s a pity. ASI is a clear feature to show what AGW is doing. Other events will be less concentrated and eyecatching, so much easier to deny any interrelation.
I tend to get to a new forecast. I do think this new pattern will regularly return in the coming few years. Maybe the winters might get less severe, thus still affecting the inevitable demise of the sea ice. I don’t think the reorganisation of NH atmospheric circulation is solely dependent on the state of the sea ice. There are more processes at work. A new stage will be met as soon as the stored heat in deeper ocean layers start to manifest consequences.
At some point, an anomalous sort of ENSO event will rise, and among other regions Antarctica may well be the place to look for new action. After all, it has been a bit quiet over there… (right, AbruptSLR?)
A last word on the high concentration swath on the Siberian side… When MODIS is studied, it is obvious that the properties of it’s ice are much different from the core pack. It is loose and thin. It is one of the reasons I think a qualitative interpretation should be added to the raw numbers come this year’s minimum.
The state of ASI isn’t going to get better, even though there now are obvious processes to promote a long tail… hat tip to Chris Reynolds, who supposed that even before this summer arrived.
Does it mean pro’s like Maslowski or Wadhams have it all wrong?
No. A first ice-free Arctic (less than 1 mkm2 remaining sea ice) at minimum is possible any year under the right conditions. But there’s evidence now in the real World how this will fit in a “long tail”.
