Polar bear habitat update: ice forming along Hudson Bay, Wrangel & Franz Josef Islands surrounded

From Polar Bear Science

Dr. Susan Crockford

Western Hudson Bay polar bears near Churchill will be able to leave shore within days, at most one week later than in the 1980s, although you wouldn’t know that from the climate change activists at Polar Bears International who have spent the last week promoting some egregiously false and misleading statementsPBI controls the narrative surrounding Western Hudson Bay bears through their partnership with the biggest polar bear tourist outfits in Churchill and online.

Yesterday, it was “See how the climate crisis is changing their world”.

Developing no slower than it did in 2007 (16 years of no change), Arctic sea ice is providing polar bears in southern regions with their second-most critical feeding opportunities while in areas like Wrangel Island and Franz Josef Land, they now have easy access to and from important summer refuge/maternity denning islands. And contrary to predictions of increased ‘conflict’ between polar bears and people around Churchill, there have been fewer problem bear reports there in recent years, this year included. In other words, there is no ‘climate crisis’ for polar bears, even in Western Hudson Bay, and recent models of a dire future for polar bears are based on totally implausible worst-case climate scenarios. Sea ice loss since 1979 has been so gradual that polar bears have been able to adapt, either through natural selection or changes in behaviour.

Arctic Sea Ice Conditions

From the NSIDC, October summary shows no declining trend in sea ice coverage since 2007, despite repeated claims by some activists that sea ice conditions have been continuously deteriorating:

What the ice charts show

Close-up images take from the chart above for 9 November 2022 (overall ice coverage 9.5mk2)

Western Hudson Bay

Freeze-up this year has been a bit slower than 2020, which was as early as the earliest freeze-ups in the 1980s, but not by much. In the 1980s, most bears left for the ice at freeze-up (10% sea ice coverage) about 16 November ± 5 days (Castro de la Guardia 2017, see graph below). The earliest the bears left the ice was in 1991 and 1993, on 6 November (Julian day 310)–in 2020, most bears were gone by 8 November, one of the earliest dates on record.

Therefore, freeze-up dates of 10-12 November or so (Day 314-316) for 2017, 2018, and 2019 were some of the earliest freeze-up dates recorded since 1979 (the earliest being 6 November, Day 310, in 1991 and 1993), even earlier than the average for the 1980s. Barring offshore winds that force the ice away, this year should be similar.

That means Explore.org PBI-affiliated moderator ‘Cloud’ was passing along disinformation to viewers when she said two days ago [my bold]:

“The ice is just starting to form on Hudson Bay. It is much later than years past, but typical for our present times.”

Virtually all Western Hudson Bay bears leave the shore within about 2 days of sea ice concentration reaching 10% (Castro de la Guardia 2017), although Southern Hudson Bay bears leave when it reaches about 5% (Obbard et al. 2015, 2016). In other words, the bears go as soon as they possibly can (Stirling et al. 1977).

Hudson Bay Sea ice coverage

Weekly coverage at 7 November compared to previous years and the long-term average (courtesy Canadian Ice Service) for the NW sector of the bay, showing just how little change there has been in recent decades:

Daily coverage for 9 November:

and to the south…

Churchill Problem Bears

After 15 weeks onshore this year, there have been few problems with polar bears in Churchill:

Compare the above to the same week in 2016, when freeze-up was quite late:

Polar bear photos from Wapusk National Park

Courtesy the Explore.org web cams

Four bears sharing a seal kill, 5 November 2022.
Female with two cubs, 8 November.

Below: two males sparring vigorously, 8 November.

References

Castro de la Guardia, L., Myers, P.G., Derocher, A.E., Lunn, N.J., Terwisscha van Scheltinga, A.D. 2017. Sea ice cycle in western Hudson Bay, Canada, from a polar bear perspective. Marine Ecology Progress Series 564: 225–233. http://www.int-res.com/abstracts/meps/v564/p225-233/

Obbard, M.E., Stapleton, S., Middel, K.R., Thibault, I., Brodeur, V. and Jutras, C. 2015. Estimating the abundance of the Southern Hudson Bay polar bear subpopulation with aerial surveys. Polar Biology 38:1713-1725.

Obbard, M.E., Cattet, M.R.I., Howe, E.J., Middel, K.R., Newton, E.J., Kolenosky, G.B., Abraham, K.F. and Greenwood, C.J. 2016. Trends in body condition in polar bears (Ursus maritimus) from the Southern Hudson Bay subpopulation in relation to changes in sea ice. Arctic Science 2: 15-32. DOI: 10.1139/AS-2015-0027

Stirling I, Jonkel C, Smith P, Robertson R, Cross D. 1977. The ecology of the polar bear (Ursus maritimus) along the western coast of Hudson Bay. Canadian Wildlife Service Occasional Paper No. 33. pdf here.

via Watts Up With That?

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November 11, 2022 at 04:42AM

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