[Arctic sea ice] Extent is, however, just a two-dimensional measure of how Arctic sea ice is trending. We know that the third dimension — thickness — has also been melting away (see “Arctic sea ice volume: The death spiral continues; One-year-old ice in Beaufort Sea now a foot thinner than in 2009″).
The best modeling of Arctic sea ice volume is done by the Polar Science Center of the Applied Physics Laboratory at the University of Washington. They have recently improved their PIOMAS model using the best observational data — and they have released their data for others to analyze. They have also added ‘conservative’ error bars to their estimates. Finally, they just published their reanalysis in the Journal of Geophysical Research, “Uncertainty in Modeled Arctic Sea Ice Volume.”
Their key conclusion is that the death spiral of Arctic sea ice continues:
… the 2010 September ice volume anomaly did in fact exceed the previous 2007 minimum by a large enough margin to establish a statistically significant new record.
So those who have been asserting that the Arctic is in some sort of recovery are wrong. Quite the reverse.
Here is PSC’s improved 30-year trend-line for the reduction in volume:
Daily Sea Ice volume anomalies for each day are computed relative to the 1979-2010 average for that day of the year.
PSC reports, “Monthly averaged ice volume for June 2011 was 15,700 km³. This value is 37% lower than the mean over this period, 47% lower than the maximum in 1979, and 2.5 standard deviations below the trend. Shaded areas represent one and two standard deviations of the residuals of the anomaly from the trend.”
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