Wednesday, 15 June 2016

Sea Ice is Disintegrating North of Svalbard

Ten Mile Wide Chunks of Arctic Sea Ice are Disintegrating North of Svalbard

14 June, 2016

Over the past 10 days, the rate of sea ice extent loss in the Arctic has slowed down somewhat. And as a result sea ice extent measures, though maintaining in record low ranges, are much closer now to the 2012 line. Low pressure systems have come to dominate the Arctic Ocean zone. And the outwardly expanding counter-clockwise winds from these systems have tended to cause the ice to spread out and to thin. In the past, such events were seen as an ice preserving feature. But this year, there’s cause for a little doubt.

The first cause comes in the form of record Arctic temperatures for all of 2016. As Zack Labe shows in the compelling graphic below, not only has the first half of 2016 been a record warm six months for the Arctic, it’s been a record warm half-year like no other.

Zach Labe
(The first half of 2016 is about 1.5 C hotter in the Arctic than the previous record hot year. It’s a huge jump to new record warmth that should cause pretty much everyone to feel a deep sense of concern about this sensitive region. Image source: Zack Labe.)

And if extra heat is guaranteed to do one thing — it’s melt frozen water. We can see that in the current near record low snow coverages for the Northern Hemisphere. We can see it in the fact that — despite what would be ‘bad melt’ weather conditions such as cloud cover and low pressure systems dominating the Arctic during the middle of June — Arctic sea ice extents are still in record low ranges and Arctic sea ice volume continues to track just below 2012’s record low trajectory. And we can certainly see it in the fact that despite the clouds that would normally promote cooler Arctic conditions during this time of year, surface temperatures have remained well above normal for the majority of June.
Overall, these conditions are unprecedented for the Arctic. And, in microcosm, we can tell a little bit of this story of heat by tracking the life of a ten mile wide hunk of ice that was recently blown away from the ice pack and into the warming waters north of Svalbard.
Ocean Zone North of Svalbard — A New Sea Ice Melt Field

Ice Chunk June 8
(June 8 — a 10 mile wide hunk of sea ice exits the ice pack North of Svalbard. LANCE MODIS image.)

On June 8th, this ten-mile wide chunk of ice was ushered away from a thinning but concentrated grouping of ice about 80 miles to the North of the Island Archipelago of Svalbard. In past decades during June, the sea ice had tended to remain closer to Svalbard, often enveloping this Arctic island chain straddling the 80th parallel. But during recent years sea surfaces around Svalbard have dramatically warmed due to a human-forced heating of the atmosphere and oceans. And today, sea surface temperatures surrounding Svalbard range from 1 to 8 degrees Celsius above 20th Century averages.

That’s still cold water in the range of 32 to 46 F. At least to the human perspective — as neither you nor I would find it a pleasant experience to plunge into sea waters that are still relatively close to freezing. But to sea ice, this water is basically warm enough to represent an oceanic killing field.
Arctic sea ice june 10 frame 2
(June 10 — the large ice island shatters in waters warmed by climate change. LANCE MODIS image.)

By June 10, our ten mile wide hunk of ice had been ejected about 30 miles into this warm water zone north of Svalbard. After only two days, the previously contiguous structure of the ice is riddled with cracks large enough to be plainly visible in the 250 meter satellite resolution. The sudden contact with warmer waters was more than enough to shatter the surface of this island-sized hunk of Arctic sea ice.

Export into warmer waters has long been a melt issue for ice moving out through the Fram Strait. And loss of ice in this fashion due to strong winds circulating clockwise around Greenland has become a growing concern. Ice originating in the thick (though much thinner than in past decades) ice pack north of Greenland can be funneled along the Greenland Coast and eventually propelled out into the warmer waters of the North Atlantic where it has no chance to survive.
Arctic sea ice June 13 frame 3
(June 13 — the ice island breaks into tiny pieces. LANCE MODIS image.)

But this is exactly what happened to this 10 mile wide chunk of ice as it entered waters North of Svalbard. It exited the ice pack, lost access to the fresh water field protecting the ice. It entered 1-3 C surface waters. And it basically disintegrated.
Arctic Ocean Near Summer Melt Tipping Points?

Added Arctic heat is not just a measure, therefore, of atmospheric temperatures. It’s a measure of implied ocean surface heat and ocean heat lurking just beneath the surface. In the end, what we see is that new ways to lose sea ice are now emerging. And it appears that sea ice export into the northern Barents and near Svalbard waters is yet one more sea ice melt risk potential. It’s a matter worth bringing up due to the simple fact that this zone of ocean water was once frozen, was once a consistent part of the Northern Hemisphere ice pack. And after warming just enough, it’s a region that is now hostile to sea ice.
ARC model June 2016
(More reliable US Navy ARCc model shows rapid thinning of remaining Beaufort sea ice taking hold over the next seven days. With so much heat baked into the Arctic over the past six months, we should remain vigilant regarding outlier melt possibilities for 2016. Image source: US Navy.)

Looking north, there’s risk that human caused climate change will drive that ice hostility zone into the near polar region itself. During the melt phase, broken ice can generate a bit of negative feedback by promoting cloud formation through increased water evaporation and reduced albedo as surface melt ponds are essentially dumped back into the ocean. But such floes are at the mercy of transport and waves. And they sit upon a warming surface ocean. A discontinuous floe can hit a melt tipping point pretty rapidly — covering a large region and then disappearing in a very short period. We’ve seen instances of such events during late June for Baffin Bay, Hudson Bay, and the Kara Sea.
Now, much of the Arctic Ocean is covered by these floes. And with so much heat in the system, it’s worth considering that the old rules no longer fully apply. It’s worth realize that the ice is dancing in an increasingly tenuous temperature zone between the warming waters below and the warming airs above.
Hat tip to Neven

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