The lowest point has been reached on all sea ice area and extent graphs, and so the melting season has ended. I'll have more on the details later this week, but here's a quick preview of one of the most important features of this melting season, and that's the decimation of multi-year ice (MYI) on the Pacific side of the Arctic.
Here's a nice video that shows how the melting season developed and ended, based on AMSR2 data. It's made by Felicia Brise of the University of Hamburg, and I've taken the liberty to upload it to YouTube:
There's a stunning contrast between the destruction on the Pacific side of the Arctic, and the relative stable and compact situation on the Atlantic side of the Arctic, even though the ice there was thinnest at the start of the melting season. In fact, this region of first-year ice was so large that it even covered the North Pole, perhaps for the first time on record. I even speculated in my 2014/2015 Winter analysis that under the right conditions the North Pole could become ice-free this year.
But the opposite happened, the first-year ice on the Atlantic side was spared (there was also remarkably little transport of ice through Fram Strait) and it was the multi-year ice on the Pacific side that took barrage after barrage of warm, sunny weather. Now that the ice age distribution maps (developed by J. Maslanik and C. Fowler, and currently produced by M. Tschudi of CCAR) have been updated, we can see how things have proceeded since my last blog post on the subject three weeks ago:
As expected, all of the 5+-year old ice on the Pacific side of the Arctic has disappeared in truly spectacular fashion. As there wasn't that much 4-year old ice to begin with, there will be less of the oldest class of ice next year. On the other hand a lot of the 3-year old ice (green) will become 1 year older, and as said, first-year ice (dark blue) got off lightly.
Nevertheless, it seems that part of the rebound in MYI that happened since 2012 has been wiped out (something I speculated about almost two months ago in this guest blog for the Guardian Environment page). We'll know how much exactly when the NSIDC puts up their monthly analysis two weeks from now. Of course, ice age doesn't necessarily tell us how thick the ice is - this isn't our (grand)fathers' Arctic anymore - but it gives us an idea of long-term changes in the Arctic.
Another indicator is sea ice volume, both modelled and observed. To know whether 2015 will dip below rebound years 2013 and 2014, we'll also have to wait a week or two for the PIOMAS model to be updated. Either way, yet another fascinating melting season is now behind us. Thanks for watching.