Calculated from April PIOMAS gridded data, source.
Region - all ice pack,
Month - April. Originally posted March data, but now updated to April the month of peak volume.
Volume contribution for above and below 2m thick sea ice. 2m having been chosen because above this thickness growth is mainly compression and ridging, below 2m growth is mainly thermodynamic, so the 2m split represents a good proxy for young ice (<2m) and old ice (>2m). This also shows how the volume loss has previously been from thicker older ice.
Conclusion; despite this year and the previous two having similar net volumes, the decline of the pack is continuing.
What will happen in June when the Arctic Ocean melt starts in earnest with all that thinner ice?
I'm reminded of Maslanik et al, 2007, "A younger, thinner Arctic ice cover: Increased potential for rapid, extensive sea-ice loss."
This extreme and abrupt loss of ice cover in 2007, following the extensive and sustained reduction in the oldest, thickest ice beginning in the late 1980s, is consistent with the premise that younger, thinner ice is likely to be more sensitive to melt and to area loss due to ridging and rafting, with a variety of implications for the basic nature of the Arctic Ocean...
...the mean age and thickness of ice within the remaining multiyear ice pack have decreased due to loss of the oldest ice types, and the remaining older and thicker ice is now confined to a much smaller portion of the Arctic Ocean than in earlier years. Given this, the ice cover is likely to be increasingly susceptible to large, rapid reductions in ice extent and fractional coverage.
Source spreadsheet available here.