I think we all remember what the conclusion was after the last freezing season (see 2011/2012 Winter analysis):
sea ice on the Atlantic/Siberian side of the Arctic looks vulnerable, sea ice on the Pacific/North American side should be thicker. So far there has been a very clear confirmation of the first half of this conclusion, in that the ice on the Atlantic side of the Arctic, along the Siberian coast, has retreated very fast, perhaps even faster than last year.
This comparison I made a couple of days back (for the Fringe Fries 2 blog post) shows it well. For a more recent comparison I refer you to the Concentration Maps page on the ASI Graphs website.
I now want to take a look at how the ice on the other side has been doing so far. The Pacific/North American side basically consists of three regions: the Canadian Archipelago, the Beaufort Sea and the Chukchi Sea. In last month's blog post concerning the Northwest Passage it became clear that the Canadian Archipelago was mostly filled with first-year ice, but because of a relatively cold freezing season the ice was probably a bit thicker. The ice in the Northwest Passage and the rest of the Archipelago has been holding up pretty well, better than in previous years (as confirmed by the MASIE extent graph), but due to high temperatures and quite a bit of insolation in the last couple of weeks, the NWP now seems to be breaking up from the inside out. As the fast ice in Nares Strait broke up 10 days ago and ice transport from the Arctic Basin is about to start, I don't think the ice in the NWP is going to hold out much longer.
Because the Chukchi and Beaufort Seas are neighbours, I have made this comparison of University of Bremen sea ice concentration maps on July 7th in the 2004-2012 period, showing both regions (click for a larger version):
This year's ice in the Beaufort Sea clearly isn't any stronger than it was in previous years. We had already received a hint when the NSIDC released ice thickness data from IceBridge flight missions over parts of the Beaufort Sea, and the current big polynya and very low ice concentration there seem to confirm that this region isn't going to put a brake on this year's melt. But the region right next to it, the Chukchi Sea, just might.
It's obvious from the image above that 2012 is quite a bit behind record years 2007 and 2011. This NSIDC/NIC regional extent graph is showing the same:
Actually I'm a bit surprised that the sea ice area decrease in the Chukchi Sea hasn't progressed as much as in other years. Here's a comparison panel of the Chukchi Sea region from June 13th from the first Fringe Fries post. In most other years the edge of the ice pack has moved close to or past Wrangel Island, but this year the island is still well surrounded by ice.
In itself this isn't definite proof of anything, but it could be an indication that the ice here is thicker and stronger. Or it could mean that the sea surface temperatures are particularly low, sparing the ice at the edge of the pack. Or a combination of both.
The only info I have that says anything about ice thickness is this last image from Russian scientific institute AARI of the distribution of multiyear/old ice, dated May 29th:During the freezing season a band of multi-year and (I presume) thicker ice was transported all the way from the Beaufort Sea to the area where the melting has slowed down considerably. The influence of this ice on the final shape of the ice pack, and thus the outcome of the melting season, should not be underestimated. Both in 2010 and 2011 a relatively large area of ice just north and west of the Chukchi region managed to survive long enough for freezing temperatures to take over in September. I referred to this phenomenon as The Arm in 2010 and had something about to say about it in the final analysis of last year's melting season as well.
However, the amount of multi-year ice on the Pacific side of the Arctic isn't the be all and end all of final ice pack contours, as was proven in 2007. The ice was probably thicker back then, but it didn't matter one bit for the shape at the minimum. All of the ice on the Pacific side of the Arctic had been melted or transported toward the Atlantic. During my research for the recent Ocean heat flux blog post, I came across this 2009 research paper by Woodgate et al .: The 2007 Bering Strait oceanic heat flux and anomalous Arctic sea-ice retreat (a summary of which has been posted in the Papers section earlier this week). This paper shows that due to atmospheric patterns a large amount of oceanic heat was transported through Bering Strait in 2007, which played a significant role in the extent and area records that were set at the end of the melting season.
Here are a couple of excerpts from the paper that show why heat transport through Bering Strait, and thus SSTs in the Chukchi Sea are important:
- We suggest the Bering Strait inflow influences sea-ice by providing a trigger for the onset of solar-driven melt, a conduit for oceanic heat into the Arctic, and (due to long transit times) a subsurface heat source within the Arctic in winter.
- Year 2007 yields a clear record-length maximum, estimated at 3.5 x 1020 J/yr from A3 data alone and at 4–4.7 x 1020 J/yr including a 10–20 m surface layer. Adding 1 x 1020 J/yr for the ACC yields a total heat flux of 5–5.7 x 1020 J/yr. This is almost a doubling of the total 2001 heat flux (2.6– 2.9 x 1020 J/yr), and 1 x 1020 J/yr greater than the previous high in 2004 (4.3–4.8 x 1020 J/yr).
- How relevant is this amount of heat (3–6 x 1020 J/yr, i.e., 10–20 TW) in the Arctic? This much heat could melt 1–2 million km2/yr of 1 m thick ice.
- The Bering Strait heat flux is also comparable to the solar input to the Chukchi Sea, 4 x 1020 J/yr (1300 MJm2 yr1, 1998–2007 range [Perovich et al., 2007] (and subsequent extension), Chukchi Sea area 350 x 103 km2).
Later this week I'm writing a blog post that - among others - compares this year's sea surface temperatures to those of previous years. But I can say in advance that the SSTs are much lower this year in the North Pacific, Bering Strait and Chukchi Sea. As we all know some pretty extreme weather conditions this winter caused a huge amount of ice to form in the Bering Sea (see blog post), and although that ice melted out very quickly once the melting season got underway, it very well could have that buffering effect we speculated about at the end of the freezing season.
To give you an idea, here's what SSTs in the Bering Sea currently look like (from this blog post by Bob Tisdale):
I'll be writing more about this some other time as well.
To conclude: As things currently stand I think a combination of thicker ice and relatively low sea surface temperatures will turn the Pacific side of the Arctic yet again into a stronghold. It might very well prevent new extent/area records, although weather patterns are still the main factor, especially towards the end of the melting season. A minimum that is reached two weeks later rather than earlier, can make all the difference.
Or will these holes in the ice pack in the Beaufort Sea and in the Chukchi Sea, just to the north of Wrangel Island, play a role as well? Yes, some of the holes are in the Arctic Basin and East Siberian Sea as well. I'm not sure exactly where those demarcation lines are (see regional map on Cryosphere Today).
This just popped up here and there in the media today:
Ice delays Shell Alaska drillingHeavier than expected ice in Arctic waters off Alaska will likely delay until August Shell's long-anticipated exploration drilling in the Chukchi and Beaufort Seas, a company spokesman said on Friday.
Shell, which wants to search for oil in what are considered remote but promising frontiers, had planned to start the wells this month, said Curtis Smith, a company spokesman in Anchorage.
Sea ice is "the number one reason we won't be drilling in July," Smith told Reuters. "At this point, we're looking at the first week of August."
While sea ice cover is sparse in most of the Arctic, ice off Alaska is thicker than in recent years, and that ice is melting fast, according to the US National Snow and Ice Data Centre.
Shell plans to drill two wells this year in the Beaufort at a prospect about 20 miles offshore, and three in the Chukchi about 70 miles offshore. Drilling must take place during the brief ice-free season, since federal approvals for the plans require that Shell cease all operations for the year by 31 October.
The schedule is especially tight in the Chukchi, where Shell must cease drilling into known hydrocarbon-bearing zones by late September, with top-hole drilling allowed after then, Smith said.
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