I agree with Neven, a complete ice-free Arctic this year is completely unrealistic. So far, the average Arctic SIE decline have been about 13% per decade by September. Roughly speaking, per NSIDC the SIE have declined by approximatively 2,5 Mn km2 during the last 35 years or so. If that pace would to continue, 2050 would be a much more realistic year to have ice-free conditions in the Arctic basin.
Personally, I don't think we'll see the race to the bottom until next switch to negative PDO occurrs. Slushy and fractured ice should be the dominant mode for the next 10-15 years.
Best, LMV
Excuse me, but SIE is irrelevant. Ice melts by volume, not by extent. Every extra Joule of energy converts to certain extra _volume_ of ice melt. Not to certain extra _area_ of ice cover melt. You can have same SIE for both 5-meters thick ice, and 0.5-meters thick. Obviously you'll need ten times more energy to melt the former than the latter. But if you only look to extent, you'd have NO idea about that. So why exactly should we pay any attention to your "based on SIE, ice-free is some time around 2050"? We should not. It's simply wrong.
If you do not understand such a simple fact, then i doubt we should pay attention to any thoughts of yours about more complex matters, until you do your homework. If you do understand, then it means you lie to us here about what you're actually thinking, in which case the conclusion would be the same: your opinion is of no importance.
There difference is, if it's the latter, then we're unable to help. But if it is the former, then we may be able to.
Neven's own blog entry
last October has the famous video, displaying annual minimum ASI volume for 1979...2015 period. If you'd pause it at 30 seconds mark, then you will see very clearly what's going on per-decade. It's very simple to see:
1980s = nearly 14M km^3 average annual minimum ASI volume;
1990s = nearly 12.5M km^3;
2000s = nearly 8M km^3;
2010s (so far) = nearly 5M km^3.
The latter number is expected to dip much down, because 2010s are not done yet, and the remaining 4 years, following this general multi-decadal trend, should be well below 5M km^3, thus pulling the average for 2010s decade down. To some 4M km^3 at very least - possibly much lower, even.
Even from this very basic statistic it is clear that 2020s are well expected to loose another ~4M km^3 of annual minimum volume, thus making it to 0M km^3 by ~2030. In reality, though, thin ice is unable to prevent storms and even simply somewhat strong winds to produce wave action, breaking thin ice apart into small pieces and mixing it with surface waters, which greatly accelerates melt (as we've seen by GAC 2012). And the thinner and weakier (structurally) ASI gets, the less intense wind becomes the "breaking point" in this mechanic. Which is why even 2030 is too optimistic an estimate.
Worse, there are other non-linear factors at play, as well. For example, during the peak insolation period, the further north you go within Arctic, the _more_ insolation you have per square meter. In the past, "far north" arctic sea ice was thick enough and cold enough to reflect most of that. Nowadays, it increasingly is not. The amount of extra energy entering the surface waters + ice system as a result of that, in the CAB, grows up non-linearly - and so does the amount of ice melt by that extra energy. There are many other factors, some positive feedbacks, some negative. Which is why you have Wadhams, Maslowski and some others predicting 1st ice-free year as soon as before 2020, and this is why you see some people talk about even this season's chances to end up ice-free (more specifically - less than 1M km^2 ASI minimum area). In this case, the area is used to quantify the "largely ice-free Arctic" event for the simple reason: it's _visible_ and can be presented to the public as such (i.e. "come on, just look on this satellite photo, there is almost no ice left!" way).
That all said, i wonder if you would be angry at me. If you would, then please consider this: i had few moments to write and desire to do so, but in my opinion, many others would simply not bother doing so. They would simply discount you as a worthy voice here, without letting you know in any way - because they would consider it a waste of time and forum space to write something like this post. So then who's doing better for you - i, or they?
Cheers.
