A simple technique to visualize 1-week changes in the pack was used before by others, consisting on using only two images (in this case UH AMSR2 Jun 25 and Jul 02) and smoothly transition from one to the other, ignoring the real variations.
What strikes me about this is -- well, a lot of things, really -- but in particular the devolution of the
eastern Beaufort into a killing field
and the continued development of the CAA/CAB crack. I've been somewhat skeptical that the crack would play out as a "real" feature rather than a temporary artifact caused by wind driving the ice. But even just an open/close boundary created by wind oscillations does retain a structural weakness.
If the east flank of the Beaufort collapses as dramatically as AMSR2 suggests it's about to, then there's every reason to expect that the same factors driving melt in the Beaufort can infiltrate along the structural instability of the crack. Indeed, while there are reasons to be suspicious of HYCOM's methodologies, their thickness map also shows propagation of melt along the CAA/CAB boundary, at least as far as Borden Island. HYCOM also appears to show separation along the west coast of Ellesmere, although I'm less convinced that has a counterpart in AMSR2.
Between Borden and Ellesmere is Ellef Ringnes Island, long considered the bastion of the "cold core" of the Arctic environment. The station on that island, Isachsen, consistently reported the coldest summers of all Arctic weather monitoring stations. Accordingly, Ellef Ringnes marked the western vertex of the "triangle" (broadly speaking: Ellef Ringnes - Cape Morris Jessup - North Pole) of protected ice with greater thickness and better tendency to oversummer.
Last year, we saw the right vertex of that triangle under attack when open water propagated along the north coast of Greenland from the east. If the Beaufort's collapse, couples with a CAA/CAB crack that originated as a wind effect but evolves into a melt feature, then we may very well see damage on the opposite side of what passes for a safe harbor for ice. We're a long way -- hopefully -- from that triangle of ice actually melting out in its entirety (because that's effectively the same thing as a BOE). But nibbling away at its edges, especially in relatively novel ways, damages the integrity of the ice and reduces its ability to resist melting in later years.
In the meantime, this directly targets volume in a way that won't necessarily be reflected in area or extent measurements and exposes the normally secure reaches of the CAA to melting factors from the
north. Nothing about this is good, even if it doesn't show in the bottom line metrics.