You can't navigate through multiyear ice... photo: arcticroute.com via flickr.
You've probably seen all sort of predictions about when the Arctic will see it's first ice-free summer in, umm, all of human history. Well, the University of Manitoba's David Barber, just returned from an expedition to examine multi-year ice in the Beaufort Sea, has told Reuters that, for all practical purposes we're already there:Barber's expedition failed to largely find the multiyear ice they sought, instead finding hundreds of miles of 50cm-thick "rotten ice" that could be navigated through.
Multiyear Ice is the Barrier to Development of Arctic
From a practical perspective, if you want ship across the pole, you're concerned about multiyear sea ice. You're not concerned about this rotten stuff we were doing 13 knots though.
I would argue that, from a practical perspective, we almost have a seasonally ice-free Arctic now, because multiyear sea ice is the barrier to the use and development of the Arctic.
Add to all this news via Climate Progress which points out that as winter sets in Arctic sea ice is now refreezing more slowly, and you start to get a picture of what's happening as the Arctic warms three times more quickly than elsewhere.
Arctic Sea Ice
Arctic Sea Ice Melt 20 Years Ahead of Schedule
NASA Confirms Dramatic Thinning of Arctic Sea Ice - Multi-Year Ice Area the Size of Alaska Lost
2009 Arctic Summer Sea Ice Minimum Third Lowest on Record - Well Outside Natural Variability