Six good years in a row for the polar bear subpopulation used to foretell species demise

From Dr. Susan Crockford’s Local weather And so forth.

Posted on July 27, 2020

In one thing resembling a brand new sample for Western Hudson Bay polar bears, a lot of the animals are nonetheless out on the ice in late July this 12 months, similar to they had been within the 1980s. The identical factor occurred final 12 months however was disregarded as a cheerful anomaly. Nonetheless, after final fall’s 1980s-like early freeze-up, this makes the sixth 12 months in a row of excellent to excellent sea ice situations for Western Hudson Bay polar bears. No marvel polar bear consultants haven’t printed these information: good sea ice situations together with polar bears coming ashore fats and wholesome are usually not simply inconvenient – they threaten to destroy the extinction panic narrative that depends upon Western Hudson Bay bears displaying proof of hurt from diminished sea ice.

Fats mom and cub onshore at Wakusp Nationwide Park, Western Hudson Bay 18 July 2020, one of many first of the season.

Maybe the primary bear off the Western Hudson Bay ice got here ashore simply south of Churchill in Wakusp Nationwide Park (at ‘Cape East’), 13 July 2020, courtesy Discover.org livecam and was in excellent situation.

The primary of polar bear researcher Andrew Derocher’s collared bears was reported off the ice on 17 July. Per week later (24 July), he reported that solely three of his 14 collared WH females had come ashore (see map under).

There was truly way more ice over Hudson Bay on 24 July than the map Derocher presents above as a result of he makes use of ice charts that show solely ice >50% focus. The Canadian Ice Service extent of ice cowl (under) exhibits ice >15% focus and explains the tagged bears that seem on Derocher’s map to be in open water:

Stage of improvement charts for the NW sector under present that the remaining ice is thick first 12 months ice > 1.2m thick (darkish inexperienced):

The sample of ice retreat over Hudson Bay this 12 months is remarkably just like the common for 1971-2000 (see under) calculated by Ian Stirling and colleagues in help of their declare that earlier breakup of sea ice brought on by international warming threatens the longer term survival of Western Hudson Bay polar bears (Stirling et al. 2004):

Under is the mid-July weekly sea ice thickness chart for 2020 displaying the general sample of ice akin to the medium gray space within the above determine (notice the CIS chart under is rotated clockwise relative to the determine above), the place the darkish inexperienced is thick first 12 months ice >1.2m:

Not since 2009 has there been fairly a lot thick ice so near shore at mid-July (under). Polar bears weren’t off the ice till August in 2009 and had been reportedly in good situation and plentiful within the space round Churchill.

Besides maybe for 2019, which had nearly as a lot:

In 2018, there was nonetheless fairly a little bit of ice nevertheless it was extra centrally situated:

A search of the CIS archives exhibits there was sufficient for some bears to remain on the ice into July from at the very least 2015.  In 2019, Derocher’s collared bears had been as late coming off the ice as they’ve been this 12 months, with many nonetheless on the ice as of 27 July (see under).

In different phrases, this isn’t the primary 1980s-like breakup 12 months for Western Hudson Bay polar bears in recent times (Crockford 2020), as Derocher claimed in his tweet on Saturday (25 July: “Local weather change stays the long run menace: 1 regular 12 months doesn’t alter the tendencies“):

three W Hudson Bay polar bears tracked by satellite tv for pc are ashore. Others are clinging to the final bits of ice. One other seal could be a bonus as there’s treasured little to eat ashore. Local weather change stays the long run menace: 1 regular 12 months would not alter the tendencies. pic.twitter.com/JM7p92nsUa

— Andrew Derocher (@AEDerocher) July 25, 2020

The truth is, he admitted final 12 months (in August 2019) that the Hudson Bay ice had been “just like the 80s” and that Western Hudson Bay polar bears had had a “good 12 months” – however then insisted it was the primary such good 12 months in a long time and thus didn’t rely for a lot.

Nonetheless, as much as the summer time of 2019, ice situations for Western Hudson Bay bears had already been comparatively good for the final 5 years and this 12 months makes it six, since freeze-up within the fall of 2019 was sooner than the 1980’s common for the third 12 months in a row.

What number of current years of sea ice information that doesn’t help the ‘long run pattern’ for Western Hudson Bay will change the thoughts of polar bear biologists? Already, the breakup and freeze-up information has not supported the assumed ever-declining pattern if you happen to checked out what’s occurred because the late 1990s: the pattern was discovered to be flat between 2001 and 2010 (Lunn et al. 2016) and from 1995-2015 (Castro de la Guardia et al. 2017). Add the unpublished information since 2015 and the slight declining pattern since 1979 for the ice-free interval (see under) used to help local weather change extinction predictions (e.g. Stern and Laidre 2016; Regehr et. al. 2016) and the pattern is prone to disappear altogether.

No marvel polar bear researchers haven’t printed the breakup/freeze-up information and related dates onshore/offshore for polar bears for Western Hudson Bay since 2015. They know it might completely destroy the general public narrative of a catastrophic future for polar bears that’s been pushed for nearly twenty years regardless of sturdy proof on the contrary, as my most up-to-date ebook describes.

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 Collection 564: 225–233. http://www.int-res.com/abstracts/meps/v564/p225-233/

Crockford, S.J. 2020. State of the Polar Bear Report 2019. World Warming Coverage Basis Report 39, London. pdf right here.

Lunn, N.J., Servanty, S., Regehr, E.V., Converse, S.J., Richardson, E. and Stirling, I. 2016. Demography of an apex predator on the fringe of its vary – impacts of adjusting sea ice on polar bears in Hudson Bay. Ecological Functions 26(5):1302-1320. DOI: 10.1890/15-1256

Regehr, E.V., Laidre, Ok.L, Akçakaya, H.R., Amstrup, S.C., Atwood, T.C., Lunn, N.J., Obbard, M., Stern, H., Thiemann, G.W., & Wiig, Ø. 2016. Conservation standing of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biology Letters 12: 20160556. http://rsbl.royalsocietypublishing.org/content material/12/12/20160556 Supplementary information right here.

Stern, H.L. and Laidre, Ok.L. 2016. Sea-ice indicators of polar bear habitat. Cryosphere 10: 2027-2041.

Stirling, I., Lunn, N.J., Iacozza, J., Elliott, C. and Obbard, M. 2004. Polar bear distribution and abundance on the southwestern Hudson Bay coast throughout open water season, in relation to inhabitants tendencies and annual ice patterns. Arctic 57: 15–26.

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