Posted on June 29, 2020 |
Here is a quick compare and contrast of sea ice habitat for polar bears in Canada and the Southern Beaufort region of eastern Alaska near the end of June, 2012-2020.
Similarities between Hudson Bay ice/open water in the sea ice charts below are striking. Ice cover at the end of June shown in these charts since 2012 reinforces the fact, documented in the peer-reviewed literature, that there has been no continued declining trend in dates of sea ice breakup for Western and Southern Hudson Bay since 1998 at least (Castro de la Guardia et al. 2017; Lunn et al. 2016). WH bears are still on the ice.
As a consequence, recent declarations of impending doom for Hudson Bay polar bears, based on claims of reduced population size and health of these subpopulations – which in any case are statistically insignificant for WH and SH (Obbard et al. 2018; Dyck et al. 2017) – must be due to some other cause (Crockford 2020).
In all areas, winds rather than melt due to increased temperatures drive much of the expansion of open water at this time of year.
The only chart I have for 2012 (the year of the lowest-since-1979 summer ice minimum) is for 20 June (there is no official archive of these particular charts) :
So, for comparison I include below the 21 June chart for 2020:
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/
Crockford, S.J. 2020. State of the Polar Bear Report 2019. Global Warming Policy Foundation Report 39, London. pdf here.
Dyck, M., Campbell, M., Lee, D., Boulanger, J. and Hedman, D. 2017. Aerial survey of the Western Hudson Bay polar bear sub-population 2016, final report (26 June 2017). Status report 2017-xx, Nunavut Department of Environment, Wildlife Research Section. Igloolik, Nunavut. pdf here.
Lunn, N.J., Servanty, S., Regehr, E.V., Converse, S.J., Richardson, E. and Stirling, I. 2016. Demography of an apex predator at the edge of its range – impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications 26(5): 1302-1320. DOI: 10.1890/15-1256
Obbard, M.E., Stapleton, S., Szor, G., Middel, K.R., Jutras, C. and Dyck, M. 2018. Estimating the abundance of the Southern Hudson Bay polar bear subpopulation with aerial surveys. Arctic Science https://doi.org/10.1139/AS-2018-0004