I just never brought it up because volume has to modeled based on a variety of different sensors. Area is a direct measurement, you just count pixels in the imagery. Volume has to be calculated and a lot of assumptions have to be made.

Denialists have never accepted volume figures because they claim the models are all rigged by Liberal scientists, that the assumptions are all phony, so I never used those figures until recently when I started publishing PIOMAS data here. I only use the sea ice extent (SIE) graphs because they are clear, unambiguous, and undenialble. (SIE = area of ocean with at least 15% ice cover.) However, that is not the only dataset that's out there, its just the most convincing one.

Of course, the denialists never accepted the SIE figures either... They, like creationists, refuse to believe the science for religious reasons. I guess they have just convinced themselves that if AGW goes away they'll get their nice job at the coal mine back. Sorry for the snark, but I've been very depressed and very angry lately, and that's not a good combination.

Neven's ice blog keeps track of the monthly PIOMAS volume report. Here are the September figures and chart. Follow the links to the PIOMAS website and see the whole report. As you can see, volume didn't go below the 2012 SIE record either, but the comparison with the last few years and the averages tells the same sad story. Volume doesn't track SIE perfectly, but its pretty close.

http://neven1.typepad.com/.a/6a0133f03a1e37970b01b8d2a83128970c-800wi