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Some surprises within the polar bear sea ice habitat in mid-October 2020

Reposted by Polar Bear Science

Published on October 17, 2020 |

Arctic sea ice has grown steadily since the minimum level was reached a month ago. Ice near the coast is now developing along the Russian and Alaskan coasts, while the ice cover in the central Canadian Arctic is expanding. While it is true that the main package of Arctic ice is far from the Russian coast, bears can hunt seals long before the ice in the central Arctic basin reaches the Siberian coast, such as in the western and southern Hudson, with the rapidly developing coastal ice Bay every fall.

Speaking of Western Hudson Bay, it's been a very slow season around Churchill for problematic polar bears (photo below) – the quietest mid-October for the Polar Bear Alert Program in the last five years and perhaps the quietest in decades (which I could say) for sure, when I had the records but I didn't).

The average sea ice cover in September was the second lowest since 1979, but was still within the 3-5 km² (see graph below) that polar bear experts had falsely predicted that 2/3 of the world's polar bears would be lost (Crockford 2017, 2019, 2020)):

ARCTIC SEA ICE THICK

Compare above with 2012 on the same date, courtesy of DMI below:

BEAUFORT SEA ICE VERY CLOSE TO THE COAST

Soon the near-coast ice along the southern Beaufort will meet the pack ice advancing south and the region will be covered again – after an ice-free period of less than 3 months (see table below from July 18, 2020 to see when that Ice is left the shore:

Pruned sea ice extent on July 15, 2020 (Day 197), NSIDC Masie

And what a difference a few days make! It literally took two days for the ice cover to change significantly in the southern Beaufort Sea. As the Canadian Ice Service table below shows, until Oct. 17, the Arctic packing mass was associated with the rapidly developing offshore ice along the central Alaskan coast, meaning polar bears eager to resume the hunt will be plentiful from then on Have the opportunity today:

BARENT SEA LAGS BEHIND 2012 REFREEZE

The pack ice movement in the Barents Sea this year (picture above on the post) is behind 2012 (below), but not by much. It will probably only take a few days for the ice to reach Franz Joseph Land and the Severnaya Zemlya archipelago in the Kara Sea (middle of the picture below, third group of islands east of Greenland). However, if 2012 shows signs of this, it will likely be early December before enough inshore ice develops on the east coast of Novaya Zemlya (that long, thin island in the top right of the picture) – where all the bear problems were in early 2019. Let bears that have spent the summer on land resume hunting (similar to bears in Western Hudson Bay in a late freeze year, see discussion below). It will be later (January / February?) Before the Kara Sea is filled with ice.

Sea ice on October 16, 2012 (day 290), NSIDC Masie.

SIGNIFICANCE IN WESTERN HUDSON BAY

No ice cream yet, of course – we wouldn't expect ice cream in Hudson Bay even in the good old days of the 1980s. But this year's bears seem unusually mellow, content to wait patiently for the freeze to occur without causing much trouble, at least near Churchill. In Arviat, a little further north, the situation could develop differently. For your entertainment, see below a video of a bear at Cape Churchill patiently killing the time that waits for the sea ice:

The latest report on problematic polar bears in Churchill for Week 7 (below, Oct 5th-11) suggests a rather boring time for the Polar Bear Alert folks:

Forty-four incidents ("Incidents") are very minor overall at this time of year – and zero dealt with and zero in prison (the "Holding Facility") are virtually unknown. While last year (2019) in Churchill was also a slow year for bear problems compared to other years, it was nowhere near as slow as this year:

Compare the last two years to 2018 (below) which (like 2019) was an early year of freezing. In 2018, by the end of the second week of October, there had already been 154 incidents, 8 bears in prison and 13 caught and released on site:

In contrast, 2016 was the last year since the freeze was very late (i.e. early December), but with the bears coming off the ice in great shape, the situation in the second week of October was no worse than 2018 when the freezing up was early:

Unless the freeze is very late this year – like 1983 – this fall will be something like 1984 last week of August in terms of polar bear problems in Churchill after a similarly late start to the season as this year (which started the year). In the meeting report of the Polar Bear Specialist Group from 1985 (Calvert et al. 1986: 24) the problem bear situation from 1984 was described as follows:

"In 1984, Churchill's polar bear control program season was September 1 through November 2. more than a month shorter than the 1983 season. 69 incidents were reported and 200 man-days were expended. There was a serious encounter – an abuse that seemed to have extenuating circumstances. "(My bold)

Time will tell and will depend on whether there is a freeze in early November, as it did in most (but especially not all) of the 1980s.

REFERENCES

Calvert, W., Stirling, I., Schweinsburg, R. E., Lee, L. J., Kolenosky, G.B., Shoesmith, M., Smith, B., Crete, M. and Luttich, S. 1986. Polar bear management in Canada 1982-84. In: Polar Bears: Report on the 9th IUCN / SSC Polar Bear Specialist Group Meeting, August 9-11, 1985 in Edmonton, Canada. Anonymous (ed.). Gland, Switzerland and Cambridge UK, IUCN. http://pbsg.npolar.no/en/meetings/ pg. 19-34.

Crockford, S.J. 2017. Testing the hypothesis that routine sea ice cover of 3-5 mkm2 leads to a decrease in the population size of polar bears (Ursus maritimus) by more than 30%. PeerJ Preprints March 2, 2017. Doi: 10.7287 / peerj.preprints.2737v3 https://doi.org/10.7287/peerj.preprints.2737v3

Crockford, S.J. 2019. The polar bear disaster that never happened. Global Warming Policy Foundation, London. Available in paperback and e-book formats.

Crockford, S.J. 2020. Polar Bear Condition Report 2019. Global Warming Policy Foundation Report 39, London. pdf here.

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