Jim,

From the paper I linked to:

When considering this part [1995 to 2007]of the sea ice–volume time series, one can estimate a negative trend of −1,120 km3 year−1 with a standard deviation of ±2,353 km3 year−1 from combined model and most recent observational estimates for October–November 1996–2007.

Given the estimated trend and the volume estimate for October–November of 2007 at less than 9,000 km3 (Kwok et al. 2009), one can project that at this rate it would take only 9 more years or until 2016 ± 3 years to reach a nearly ice-free Arctic Ocean in summer. Regardless of high uncertainty associated with such an estimate, it does provide a lower bound of the time range for projections of seasonal sea ice cover. (We do note that other published estimates also have large or indeterminate uncertainties.)

So this prediction is based on 2007 data and extrapolating forward the volume losses since then based on the 1995 to 2007 trend.

With regards PIOMAS, I'm using September data, not October/November as used above. Average interannual losses are -564 km^3 per year, StdDev=1,435 km^3 for 1995 to 2007. 1995 turns out to be a reasonable choice for the steepening of the trend as with NAME.

Applying these losses to the 2007 minimum 6528 km^3, gives zero at 11.6 years, call it 12. That's 2019, at the upper end of Maslowski's calculation. Sept 2012 is 3156 km^3 down from 2007, which should have taken 5.6 years, drop the .6 and 2012 was on time - more coincidence than anything. Applying the 1995 to 2007 loss rate of -564 km^3 per year to the 2013 September average volume for PIOMAS (5043km^3) and we have 9 years to zero. That's 2022.

I think the basic message of Maslowski and Wadhams that the end could be a fast crash to very low levels before we see some length of tail (residual remaining ice) needs to be kept in mind, and should not be dismissed out of hand. But the 2016 +/-3 isn't looking so persuasive after 2013. That said Crandles may be correct and I may be wrong, the 2013 volume gain may not impact the coming maximum as much as I suspect.

Dr Serreze is one of the world's leading cryosphere scientists.