I've been doing some simple analysis of the arctic sea ice extent data in order to generate my own prediction of the summer low. I'm now almost entirely convinced that the 2011 record will be smashed in 2011.
I've based it on the Jaxa arctic data from 2002 to 2011, which I imported into a gnumeric spreadsheet. You can see from the initial image that the SIE for 2011 is below the record-breaking year 2007 and has been every day since mid-May. In itself, this should be cause for alarm, but let's go back to 2007 to see why it's even worse than you might think.
2007 was a record-breaking year, but it didn't look that way until it lurched into free-fall in the last 10 days of June, due to a 'perfect-storm' of (AGW-induced) weather conditions, which set the scene for a record loss in late September. So the fact that 2011 has been lower since May isn't conclusive.
So, what I did was take the Jaxa data an import it into a spreadsheet. My first estimates were based simply on the ice loss from previous years after July 16 bolted on to July 16, 2011. There I discovered that the SIE minimum for this year would be about 4.16million KM2 - a new record, but not by much, a mere 80,000Km2. What's scary though is that simply bolting on the curves means that we'd get a record for 7/9 of the previous 9 years.
|July 16: 2011||7347656|
But it's not a realistic estimate - it's likely to be an underestimation. That's because SIE curves tend to have some continuity between the current state (and conditions) and the future state. So I constructed a slightly better estimation. In this one, I calculated the slope of the ice loss from July 1 to July 16 and compared the ratio with the eventual ice-loss at the minimum SIE for every year.
|July 1 to July 16:||1715157|
|July 1-July 16:||781563||1379844||1221562||1696406||1158750||1214375||1031250||1108750||1210937|
|Ratio to min SIE||5.11||3.24||4.04||2.97||2.98||3.54||4.15||3.55||3.63|
|July 1-16 Extrapolated:||3.002E+05||3.503E+06||2.131E+06||3.973E+06||3.946E+06||2.989E+06||1.951E+06||2.976E+06||2.835E+06|
With this, the best-case projection (i.e. maximum minimum SIE) will be 3.95million Km2 and the worst case will be 300,000Km2 (average 2.7million Km2). That's - stunning, and stunning doesn't even cover it: a 50% ice loss from 2007 in the best case, a 93% ice loss in the worst case, 33% ice loss in the average case.
The question is then how reliable these estimates are. Well, I'd be the first to say, "not very". My projections can be skewed easily by a steep anomaly in early July 2011 which would project a much lower summer minimum than would be likely.
The irony is that 2011 has had a smoothly falling curve between May and mid-July and it was 2007 which had the sudden acceleration over July. So 2007 makes my 2011 estimate look higher than it's likely to be. So, I'll stick my neck out at this point and say I figure the arctic record will be smashed this year, it's likely to be around 20% lower than 2007, probably in the range of 3.5million Km2, almost certainly lower than 4.0million Km2 and perhaps even as low as 3.0million Km2.