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Neven

Fixed. Thanks, Wipneus.

Derek

Very back of the envelope, but if the volume declines from current levels as per the 1979-2010 trend we will have only 2.5 1000km3. With increasd albedo affects perhaps lower.

Andrew Xnn

For 2010 the anomaly graph still shows a sharp drop and subsequent partial recovery. Does anybody know the bottom date of the 2010 dip?

Is is possible we will see a similar anomalous anomaly this year?

I'm thinking we are already past the 2010 date, but not sure.

Wipneus

Andrew: Does anybody know the bottom date of the 2010 dip?

day 179 ( 29th of June): anomaly -9.179 [1000 km3]

In 2011 the last date ( first of July) has the highest anomaly -9.736 [1000 km3]

Wipneus

Derek: 2.5 1000km3

Currently absolute ice volume is 0.615 [1000 km3] less compared with 2010.

If sustained, the minimum will be around 3.8 [1000 km3]

That would be nearly on top of the exponential trend for September. But a bit below a Gompertz fit.

Lord Soth

That's two years in a row that we have seen the identical plunge of death for June. And this time, we can't blame it all on Hudson Bay.

crandles

Derek: 2.5 1000km3

Wipneus: Currently absolute ice volume is 0.615 [1000 km3] less compared with 2010.

If sustained, the minimum will be around 3.8 [1000 km3]

Derek was looking at 1979-2010 trend. Wipneus is comparing to 2010. For a third version:

Volume reduction declines of 2005-2010:

Year July August to min
2005 -6.311 -2.71 -0.384
2006 -6.053 -2.662 -0.424
2007 -6.421 -2.52 -0.194
2008 -6.187 -3.432 -0.751
2009 -6.751 -2.595 -0.403
2010 -5.85 -2.38 -0.218

Average -6.2621 -2.7165 -0.3957
Std dev 0.3117 0.3692 0.1997

2011 30 Jun volume=12.261 less Jul avg -6.2621 - Aug avg -2.7165 - to Sep min -0.3957
gives projected min volume 2011 of 2.9 k km^3.

2010 had smallest volume declines in July/Aug/Sep compared to 2005-2009 so it is not unreasonable to project lower volume than a follow 2010 path.

George Phillies

If you have the same volume drop as last year, about 4000 cubic kilometers, you go down from -7000 or so to -11,000, and -11,000 off the September minimum is close to zero, indeed it approaches being within the error bard of zero. (Hitting zero is of course an excellent calibration for the models.)

crandles

Sorry George, I don't follow. The closest I can get to a 4000 km^3 drop last year is 30 June 2009 16.642 to 30 June 2010 12.876 a drop of 3.766 k km^3 over a period of a year.

But 30 June 2011 is 12.261 which is only 0.615 below this time last year. For that 0.615 to grow to 4 in 2.5 months not a year would be a dramatic acceleration in the rate of decline.

I suspect you are not comparing the same times of year. 3rd graph in post above may help.

Average decline from 30 June to minimum over last six years is 9.37 k km^3 with a std deviation of 0.65. For 12.261 to fall to 0.94k km^3 or lower would be 3 standard deviations more drop than the average of last 6 years and should be considered very unlikely.

I mentioned that just an average drop gets us down to 2.9k km^3 but to put that in perspective it would mean that more than a third of the minimum ice volume in 2010 of 4.428 k km^3 would have disappeared.

George Phillies

I am doing something completely different than you are, which is not to say I have any disagreement with your numbers.

What I am saying is that last year there was a sudden precipitous drop in the anomaly curve. When the drop started, the anomaly was about -5000. At the pointy bottom of the drop, the anomaly was about -9000. I am comparing two months on the graph within the same year 2010. That drop has never occurred before, at least on the graphs I have seen. It is a new phenomenon. I am discussing what would happen if that very jagged change in the size of the anomaly, as seen last year, were to repeat this year.

This year, the very sharp drop started to be visible last month, with an anomaly before the drop began around -7000. If we get the same sharp change in the anomaly this year that we had during summer 2010, at the bottom this year we will be down at -11000.

This is one of those things that would be a lot easier to do over a piece of paper.

Seke Rob

Someone will have done this before [on cue, off a chart type presentation posted at tamino, plotting the annual minimum / maximum points and the annual km^3 of melt per the PIOMAS (2.0) data... every year a little bit more. Given the previous ''normal'' of 16kkm^3 and up of annual freeze and melt, one wonders what the real losses are off the Greenland ice-sheet.

hmmm, preview button does not work, so apologies if this skews the view.

Twemoran

Seke
Works fine in new tab

Climateforce

Re Fig.1: Uhm, wouldn't it make sense to put the actual year number not "Current year"?

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