I've been thinking about the relationship between volume and area, so I plotted a scatter plot of PIOMAS volume at annual minimum and CT area at annual minimum. I can't believe I've not done this before, or if I have that I've forgotten, not having seen the significance.
What initially fascinated me is the linearity, despite all the complexity of changes over the last 34 years, it's so damned linear. So the apparent acceleration of volume loss is closely tied to that of area.
I've extended that curve to zero volume for a purpose. This relationship that has held for 34 years must cease, because if maintained when the area at minimum is at 1.82M km^2 volume will be zero! This is impossible! It's worth noting here that this year's minimum was 2.234M km^2.
Crucial to answering how this relationship will fail is, I suspect, the answer to the question: Why there is a constant of proportionality of 0.222 between area and volume? I should stress that vague terms like crash aren't what I'm taking about when I say 'how', I'm thinking more about the physical processes.
Also relevant to this is the ratio of area and volume.
The jump in ratio at the end of the series is due to the volume loss of 2010. But before I start rambling on about the importance of that year...
It might seem puzzling that the ratio can jump, while the linear trend in the first graphic still holds. If you subtract the offset 1.8224 from area then the ratio is closer to 0.222, indeed the average of all the year's ratios is 0.221388, so that jump is due to volume and can be seen in the first graphic as the last three points being separated from the previous group of three (2007 to 2009) both groups being separated from the pre 2006 mass of data points. But despite the magnitude of the 2007 and 2010 events they have not caused a break away from the relationship shown in the first graphic and a deviation towards a trend that intersects the zero volume = zero area origin.
Which makes me wonder what sort of magnitude of event we face.
PS - I should have waited before posting, I'm too tired and have missed the bleedin' obvious! If you invert the relationship Area/Vol you get Vol/Area, which is thickness, I think that the problem with physical implausibility of the first graphic is due to us being on the edge of critical thickness, below which the ice cannot survive. I'm trying to pin down a figure for such a threshold or reconcile a trajectory between where graphic one leaves off and zero.
PS2 - Plot of Volume/Area which is thickness at minimum.
With reference to the PIOMAS thickness plots at the end of this post. I am now wondering if the deviation implied by the first graphic of this post could actually be relatively slow. With the ice in the interior surviving for some years. The first graphic of this post tells us nothing about rate, and both the 2007 and 2010 events were driven by anomalous weather.
First graphic redone as Volume/Area.
I'll be going over this some more, but have made some progress. Over at Neven's Sea Ice Blog I'm discussing this issue, as I went over there to ask for opinions. My latest new information is here, but the rest of the discussion is worth browsing.
Data - PIOMAS volume and Cryosphere Today Area.