British Parliament Audit: Arctic Ice free within a Decade

Tldr; between 2003 and 2011 the Arctic sea ice volume decreased by 50% or 900km³ per year. Latest PIOMAS volume reads 3,400 km³.

With a tremendous effort and more importantly in a public way the Environmental Audit Committee invited and interviewed experts and scientists to collect all evidence about the conditions in the Arctic.

Topics cover everything from methane, permafrost, black carbon over sea ice to polar bears and more. The report went online earlier this day and is the most extensive and actual reader available now.

Here is the paragraph concerning volume and the conclusion:

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My Problem with Sea Ice Extent

Since 1979 there is a sea ice extent record for the Arctic with mostly daily measurements. The trend is clear and down, so what is the problem?

Imagine a single idealized ice floe: 1 kilometer long and 1 kilometer wide with a thickness of 2 meter drifting in the Arctic Ocean - a pretty flat cuboid. Roughly 20 centimeter are visible above sea surface as freeboard. NASA’s Arctic Mosaic at highest resolution would represent the floe with 16 white pixels arranged as square.

Let’s further assume bottom- and top melting are equal and and there is enough energy available to melt 1 meter of ice from each of the six sides within a month (30 days). How much ice is left after this period? Exactly, zero.

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Yearly Sea Ice Volume Loss

The question: "When will the Arctic be ice free?" can be posed differently as: "When will we have 100% ice loss during the melting season?". The interactive chart above tries to answer second question. The yearly loss is defined as the difference between maximum and minimum volume.

'Ice free' and 'ice loss' are slightly different concepts or metaphors. A loss of 100% means the Arctic is ice free and a loss of 0% there was no Summer. Ice-free-ness implies the sheet starts phasing out somewhere in the future. Actually this is already happening and it is accelerating. The real question is when will it hit the ground? Having 100% ice loss eliminates all room for discussion, because there is no such thing as 110% loss, 100% loss simply means game over.

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Applying Gauss to PIOMAS

An accelerating trend is an invitation to do all kind of weird math to anticipate the future. I'm no exception, so here you go: The PIOMAS June data was just released stating Ice volume for March 2012 and 2011 was ~20,800 km³. That's the orange line on the left.

Now the data also tells three month later a lot of ice was already lost and the loss is approximately 1000 km³ greater than the year before. It would be interesting to know who provides an extra energy of 3x10e20 Joules to melt the ice, but that's another story. Let's assume for now the trend continues and every year an additional cube of ice with an edge length of 10km disappears. What's the math?

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Sea Ice Thickness Forecast

Just out of curiosity I wanted to know what the average sea ice thickness in the Arctic actually is. So I took the available GSFC Dataset, filled the holes and used the overlapping time range with the IJIS/JAXA data set to perform a least error approach and gained a table starting 1979-01-01 and ending 2010-12-31. This range is also covered by the PIOMAS sea ice volume data set and calculating daily thickness was easy then.

But average thickness is a value which works only within a certain range. Having an average of zero, does no way mean there are any floes with negative thickness. Also, it turns out yearly thickness minimum is not in September, but rather in December when the Arctic is covered with a lot of fresh and thin ice.

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