Apparently, some locals were upset that a polar bear that refused to be scared away from a Newfoundland community over the weekend was shot as it advanced on conservation officers and a crowd of onlookers who refused to disperse (see updated report here on recent Newfoundland polar bear sightings, with annotated map).

“Polar bear shot by wildlife officers near Catalina after being deemed public safety risk” (CBC 10 April 2017)

What these animal lovers may not realize is that Newfoundland in March and April is not a Churchill-like situation: polar bears are in strong hunting mode right now.

Polar bears in late winter and spring have an immense drive to kill and eat as much as possible. Even bears that look well fed will continue to kill and eat. Enticing smells attract them onshore as they investigate any food possibility (see list below).

Seriously, you don’t want that food possibility to be you.

Polar bears can go from watching to charging, in the blink of an eye. You can’t outrun one. Killing quickly is what they do and they are immensely strong. Polar bears generally go for a killing bite to the head. Things to think about when a polar bear is prowling your community…
Like big cats, polar bears are also stealth hunters and will use any object on the landscape to hide behind to make a surprise attack. On the ice, that would be hummocks of buckled ice or blocks of old ice caught in the pack. But on land, especially in communities occupied by people, there are hiding places everywhere: houses, cabins, sheds, garages, vehicles of all kinds, bridges, bushes, patches of trees, bus shelters.

Here is a list of the kinds of things that attract polar bears by smell (see previous posts here and here) but it’s not exhaustive:

Caches of frozen meat
Hunting refuse
Odors of cooking food
Food fed to dogs
Dogs (see this recent incident)
Human menstrual blood (see Cushing 1979, pdf below)
Stored food
Garbage
Sewage
Human graves (cemeteries)
Oils and lubricants
Vinyl seats (see photos below, from Melrose, Newfoundland last week)
Plastic-coated cables
Antifreeze
Insulation
Cameras

Photos below by Shelly Ryan of Melrose (4 April 2017) showing things that attract polar bears onshore:

This photograph was taken in the dead of winter (February 2013), with lots of sea ice offshore, by a remote camera maintained by Doug Clark (U. Saskatchewan) on the shore of Western Hudson Bay, which probably attracted the bear in the first place:

This half-finished cabin attracted a fat young female bear in eastern Hudson Bay in late February, also with lots of ice offshore:

Those upset about the bear that was shot in Catalina included Brandon Collins, a photographer who took many pictures on Saturday of the bear, which he shared with media outlets that morning, here and here, and below). He was most vocal in expressing his displeasure. In my opinion, that’s what can happen when people get emotionally attached to dangerous wild animals: they react emotionally when things go sour. Too often, wildlife photographers don’t maintain the bit of detachment they need.

Here is the statement issued by the local government minister, Neil King, which I support wholeheartedly (as did most other people):

References

Cushing, B.S. 1979. The effects of human menstruation and other substances on polar bears – interim report. pgs. 93-102 in: Polar Bears: Proceedings of the 11th working meeting of the IUCN/SSC Polar Bear Specialists Group, 25-27 January, 1993, Copenhagen, Denmark. Gland, Switzerland and Cambridge UK, IUCN. PDF here.

Truett, J. C. (ed.). 1993. Guidelines for Oil and Gas Operations in Polar Bear Habitats. Minerals Management Service Alaska, US Dept. of the Interior, Report 93-0008.

In recent years, sea ice loss over Hudson Bay has begun with open water in the NW corner (which is just as likely due to prevailing offshore winds as ice melt) rather than along the east coast but this year that patch of ice is smaller than its been for the last two years. In addition, despite two patches of open water at either end of the Beaufort Sea, most of the coast of Alaska is still covered in thick ice — much more than existed last year, yet masses of polar bears did not die as far as I know (actually, WHB bears came ashore in excellent condition last year).

Compare to previous years:

Last year at 27 May (2016), where there was also more open water in the Beaufort Sea (driven not by melt but by the strong currents of the Beaufort Gyre) and in Kane Basin (between NW Greenland and Ellesmere Island):

27 May 2015 saw open water in NW Hudson Bay almost as far south as Churchill:

All of that dark green in the charts below is thick first year ice that’s at least 1.2 m thick and brown is ice >1 year old that is 2m thick or more.

Polar bear biologist Andrew Derocher, who’s research team has been ear-tagging male WHB male polar bears in the NW sector this spring, confirms that the bears are drawn to the fragmented ice and edges of the open water in the NW where they are most likely to catch bearded seals.

Here is his plot of males (purple) and females (blue) at 24 May 2017:

Polar bear specialists Andrew Derocher and Steven Amstrup recently spent inordinate energy trying to refute the opinion piece I’d written for the Financial Post in celebration of International Polar Bear Day last month, ignoring my fully referenced State of the Polar Bear Report for 2017 that was released the same day (Crockford 2018) and the scientific manuscript I’d posted last year at PeerJ Preprints (Crockford 2017).

Their responses use misdirection and strawman arguments to make points. Such an approach would not work with the scientific community in a public review of my paper at PeerJ, but it’s perfect spin for the self-proclaimed “fact-checking” organization called Climate Feedback. The result is a wildly ineffective rebuttal of my scientific conclusion that Amstrup’s 2007 polar bear survival model has failed miserably.

This is Part 2 of my expose, see Part 1 here.

Quote #2 from my op-ed to which Amstrup and Derocher responded:

“For example, Canadian polar bear biologist Ian Stirling learned in the 1970s that spring sea ice in the southern Beaufort Sea periodically gets so thick that seals depart, depriving local polar bears of their prey and causing their numbers to plummet. But that fact, documented in more than a dozen scientific papers, is not discussed today as part of polar bear ecology.”

Amstrup responded, in part:

“Both Ian Stirling and I have published on the inter-annual and even multi-annual variation in sea ice extent, etc.  …Ian specifically mentioned in some early publications that there seemed a nearly decadal oscillation in ice thickness, etc. …Regardless, as the world has warmed and ice continued to thin, evidence of any such cycle in the Beaufort has disappeared. We did not see a crush of heavier ice in the middle of the first or second decades of the 2000s. …Why would researchers spend much time now discussing a pattern in the sea ice that no longer occurs?”

Derocher responded:

“Heavy sea ice conditions are largely a past issue for ringed seals. …It is loss of sea ice habitat as a whole that is negatively affecting ringed seals and thus polar bears.” [cited papers: Bromaghin et al (2015) and Hunter et al (2010) ]

My response to both comments on Quote 2:

Both Amstrup and Derocher claim that thick ice in spring was a thing of the past by the turn of the century, a phenomenon that no longer occurs in the Southern Beaufort now that sea ice in summer has declined. This is patently untrue.

Even though Stirling and colleagues argued in their 2008 paper that the thick spring ice conditions in 2004, 2005 and 2006 (but not those in 1974-1976) were caused by storms initiated or intensified by greater amounts of open water in previous summers, they did not deny that thick-ice conditions were present from 2004-2006 that were as severe as those documented for 1974-1975.

This is what Ian Stirling (Stirling et al. 2008:15-16) had to say about the 2004-2006 event in the eastern half of the Southern Beaufort (corroborated by seal biologists (Harwood et al. 2012, 2015):

“During our study, sea ice conditions in the southeastern Beaufort Sea showed some major differences from past years (Stirling et al., 1993 and unpubl. data). From 2003 through 2006, large areas of the annual landfast ice from northeast of Atkinson Point to the Alaska border (Fig. 1) were compressed into high pressure ridges interspersed with extensive areas of rafted floes and rubble (especially in 2005; Fig. 2). In some places, these areas extended offshore from the mainland coast for tens of kilometres. Such heavy ice reduces the availability of low consolidated ridges and refrozen leads with accompanying snowdrifts typically used by ringed seals for birth and haul-out lairs (Smith and Stirling, 1975, 1978). Although we were unable to make a quantified comparison, our subjective impression is that in 12 previous spring field seasons surveying the same area for polar bears (1971 – 79, 1985 – 87) only once, in 1974, did we observe similarly extensive areas of rubble, pressure ridges, and rafted floes.” [my bold]

Since there is evidence for such thick ice conditions about every decade from the 1960s to the mid-2000s, this makes five decades worth of data on this phenomenon: certainly enough to deserve comment by biologists and to warrant inclusion in future survival models, especially given previous catastrophic effects on polar bear health and survival.

Derocher’s cited papers (Bromaghin et al. 2015; Hunter et al. 2010) are not evidence that less summer ice was the cause of declining polar bear populations in the first decade of the 2000s in the Southern Beaufort: there is correlation with less ice, to be sure. But that correlation is meaningless given that thick ice conditions were known to have been present in 2004-2006, conditions described as at least as severe as mid-1970s events, about which much is known (e.g. Burns et al. 1975; DeMaster 1980; Harwood et al. 2000; Ramseier et al. 1975; Smith 1987; Smith and Stirling 1978; Stirling 2002; Stirling et al. 1975a, 1975b, 1981, 1982, 2008; Stirling and Lunn 1997).

Quote #3 from my op-ed to which Amstrup and Derocher responded:

“…many scientists were surprised when other researchers subsequently found that ringed and bearded seals (the primary prey of polar bears) north of the Bering Strait especially thrived with a longer open-water season, which is particularly conducive to fishing”

Amstrup responded:

“The Chukchi sea is essentially all continental shelf and is probably the most productive of the Arctic Seas. This is in contrast to the Beaufort Sea which, beyond the very narrow continental shelf, is very unproductive. Recent research has shown that this tremendous productivity and the fact that, although ice has significantly retreated, bears there still have fewer ice free days over the shelf than in the Beaufort, can explain why Chukchi Sea polar bears have not yet declined like those in the Beaufort.”

Derocher responded:

“Both ringed seals and bearded seals are sea ice obligate species: there are significant conservation concerns about both species across the Arctic. The basis of the statement that the seals are thriving is unfounded in the peer-reviewed literature. Both species are listed under the US Endangered Species Act.

The polar bears living north of the Bering Strait have not shown the same loss in body condition, survival, and reproduction noted in the neighboring Beaufort Sea because the ecosystems are vastly different in the distribution of continental shelf habitat: huge area in the Chukchi Sea, a narrow band in the Beaufort. Polar bear populations respond to local changes, and with 19 polar bear populations, there will be 19 different scenarios playing out over time. Loss of sea ice in the Chukchi Sea in winter 2017/18 may change the situation there.”

My response to both comments on Quote 3:

This quote is about ringed and bearded seals thriving in the Chukchi Sea due to a longer ice-free season that was contrary to predicted effects (Crawford and Quakenbush 2013; Crawford et al. 2015). Amstrup presents a strawman argument when he discusses Beaufort Sea seals, as does Derocher in describing Beaufort Sea polar bears. Derocher’s comment about ESA ‘threatened’ status for ringed and bearded seals is also a strawman argument. While what he says is true (USFWS 2012a, 2012b), it is also true that no other Arctic nation or the ICUN is concerned about any Arctic seal species, including ringed and bearded seals (Kovacs 2015, 2016a, 2016b; Lowry 2016): they are all listed as ‘least concern’ on the IUCN Red List.

Quote #4 from my op-ed to which Amstrup and Derocher  responded:

“…while it’s true that studies in some regions show polar bears are lighter in weight than they were in the 1980s, there is no evidence that more individuals are starving to death or becoming too thin to reproduce because of less summer ice.”

Amstrup responded:

“We know that polar bears depend on the ice surface to catch their prey. We know that increasing numbers of ice free days have resulted in poorer body condition in some areas (e.g. Southern Beaufort, Western and Southern Hudson Bay), we know that poorer cub survival has followed both declining ice and poorer body condition, and all the evidence suggests these things are linked. Perhaps this is not “proof” that less available summer ice is the cause (correlation does not necessarily imply causation), but I am not aware of evidence for any other explanation. And I don’t think the female polar bears are intentionally having cubs but not feeding them.” [my bold]

Derocher responded:

“There is evidence. Bromaghin et al 20151 and Hunter et al 20102 examine this issue.

Bromaghin et al state, “Low survival from 2004 through 2006 led to a 25–50% decline in abundance. We hypothesize that low survival during this period resulted from (1) unfavorable ice conditions that limited access to prey during multiple seasons; and possibly, (2) low prey abundance. For reasons that are not clear, survival of adults and cubs began to improve in 2007 and abundance was comparatively stable from 2008 to 2010, with ~900 bears in 2010 (90% CI 606–1212). However, survival of subadult bears declined throughout the entire period. Reduced spatial and temporal availability of sea ice is expected to increasingly force population dynamics of polar bears as the climate continues to warm. However, in the short term, our findings suggest that factors other than sea ice can influence survival.”

Hunter et al stated, “Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). … The resulting stochastic population projections showed drastic declines in the polar bear population by the end of the 21st century. These projections were instrumental in the decision to list the polar bear as a threatened species under the U. S. Endangered Species Act.”  References cited: (1. Bromaghin et al (2015); 2. Hunter et al (2010).”

My response to both comments on Quote 4:

Neither one of these responses provide evidence that more bears are starving to death or have become too thin to reproduce due to reduced summer sea ice, which was the point of my statement.

Neither of the references cited by Derocher provide such evidence: the effects cited from the Southern Beaufort, as explained in my paper (Crockford 2017) and the State of the Polar Bear Report 2017 (Crockford 2018), and reiterated in my response to Quote 2 comments above, are explained not by less summer sea ice but by thick ice in the springs of 2004-2006 (Stirling et al. 2008). Continued poor survival of subadults after 2007 may have been correlated with less summer ice but on its own is not evident of causation.

Amstrup raises the issue of poor cub survival and reduced weight of females in Western and Southern Hudson Bay. But he should know that these effects can be caused by conditions over the winter and spring that affect prey condition or availability (Crockford 2015; Ferguson et al. 2005; Ramsay and Stirling 1988; Stirling 2005), even more so than a longer ice-free season. Much has been written about them.

Previous work by Derocher and Stirling make clear that weights of bears and cub surival declined markedly in the late 1980s and early 1990s in Western Hudson Bay (Derocher and Stirling 1992; 1995a; 1995b; 1996; Stirling 2005).

For example, Derocher and Stirling, writing in the early 1990s (1992:1155), state:

“Over the last 10 years, the productivity of female polar bears in western Hudson Bay has decreased. Coinciding with the trend in reproductive output was a decline in the mean weight of females with cubs. A decline in weight was found in most other segments of the population (unpublished data). The two-fold increase in the number of cubs lost from a litter between spring and autumn during the 1980’s represents a substantial increase in cub mortality. We believe that the decline in weight of adult females was responsible for the decrease in cub survival. From the early to late 1980’s, there was a three-fold increase in the proportion of females that lost their whole litter in the spring to autumn period. These changes resulted in reduced reproductive output and changes in the reproductive status of females in autumn.” [my bold]

Similarly, Derocher and Stirling (1995b:1657), state:

“Reproduction rates declined in the late 1980s from higher levels in 1966- 1984. Litter production decreased from 0.48 to 0.34 litters per female each year over the study. Recruitment to autumn declined from 0.75 to 0.52 cubs per female each year, in part because of cub mortality between spring and autumn, which increased from 25.0% in 1980- 1984 to 50.9% in 1987- 1992. Spring and autumn litter sizes of females with cubs did not vary annually, but litter sizes of females with yearlings varied between years. The proportion of yearlings independent of their mother in autumn dropped from 81 % prior to 1980 to 34 % in 1980- 1992. After 1986, offspring remained with their mothers longer, resulting in the birth interval increasing from 2.1 to 2.9 years. Body mass of most age-classes of females and males declined in the 1980s. Unlike earlier studies that found reproduction rates to be higher in western Hudson Bay than in higher latitude populations, reproduction rates in 1986- 1992 in western Hudson Bay were similar to those of other populations. Insufficient information was available to determine the cause of declines in reproduction and body mass.” [my bold]

In other words, weight declines and poor cub survival are not exclusive to recent years in Western Hudson Bay, as implied, which  means these symptoms can have other causes besides a longer-than-usual ice-free season.

Quote #5 from my op-ed to which Amstrup and Derocher  responded:

“The failure of the 2007 polar bear survival model is a simple fact that explodes the myth that polar bears are on their way to extinction.”

Amstrup responded:

“Multiple papers published subsequent to my work in 2007 have corroborated the outcomes we projected. However, the accuracy or failure of my work to inform the Secretary of Interior* cannot be evaluated until mid century. And as the figure above shows, we are not there yet.  Reference cited: Amstrup et al (2010).”

[Derocher did not respond to this last quote]

My response to Amstrup’s comments on Quote 5:

Amstrup claims that many papers published subsequent to his work in 2007 have corroborated the outcomes he and his colleagues projected yet he does not bother to cite  a single one.

Sea ice hit mid-century-like levels before the ink was dry on their 2007 reports (Crockford 2017, 2018) and stayed at those levels. Yet polar bear numbers not only failed to decline as predicted, they have increased slightly.

Amstrup again tries to use recent sea ice and/or polar bear survival model predictions to suggest my critique of his 2007 model (based on 2006 sea ice predictions) is incorrect or premature. However, none of these papers are relevant.

Note that the model is often considered Amstrup’s work (by himself and others) because his opinion alone was used to predict how polar bears would respond to various levels of sea ice decline (Amstrup et al. 2007). As a consequence, he takes any criticism of the model as personal criticism and responds defensively (see emails in this post).

It turns out some of the assumptions Amstrup made for his 2007 model were wrong (Crockford 2017, 2018). He was wrong to ignore the Southern Beaufort thick spring ice phenomena in his model and wrong to assume that ringed and bearded seals would suffer gravely with less summer ice.

My overall response to these comments on my op-ed:

This “analysis” by Derocher and Amstrup was a weak effort at rebutting the major points of my op-ed, which was a summary of my State of the Polar Bear Report (Crockford 2018). Most of the points (Quotes 1, 2, 3, and 5) were also essential components of my 2017 critique of Amstrup and colleague’s 2007 survival model used to support listing polar bears as ‘threatened’ with extinction in the US (Crockford 2017).

There was little except bluster and misdirection in the comments made by Derocher and Amstrup. Insisting – repeatedly – that models developed after Amstrup and colleagues 2007 USGS reports were published provide evidence that my critique is premature might fool the general public but it won’t fool fellow scientists.

It would have been more appropriate for Amstrup and Derocher to have properly reviewed my 2017 PeerJ Preprint paper. However, now we know why they passed: they didn’t have scientifically valid arguments to make.

The premise of my 2017 paper, and the focus of my State of the Polar Bear Report, is that the model prediction made by Amstrup and colleagues in 2007 failed, based on observations of sea ice and polar bear population sizes estimated since then. Nothing Amstrup and Derocher have said undermines that conclusion. Polar bears are thriving because the assumptions Amstrup made about how the bears would respond to much reduced summer sea ice conditions were wrong.

References

Amstrup, S.C., Marcot, B.G. & Douglas, D.C. 2007. Forecasting the rangewide status of polar bears at selected times in the 21st century. US Geological Survey. Reston, VA. Pdf here

Amstrup, S.C., DeWeaver, E.T., Douglas, D.C., Marcot, B.G., Durner, G.M., Bitz, C.M. and Bailey, D.A. 2010. Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence. Nature 468: 955–958.

Bromaghin, J.F., McDonald, T.L., Stirling, I., Derocher, A.E., Richardson, E.S., Rehehr, E.V., Douglas, D.C., Durner, G.M., Atwood, T. and Amstrup, S.C. 2015. Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline. Ecological Applications 25(3):634-651.

Burns, J.J., Fay, F.H., and Shapiro, L.H. 1975. The relationships of marine mammal distributions, densities, and activities to sea ice conditions (Quarterly report for quarter ending September 30, 1975, projects #248 and 249). In Environmental Assessment of the Alaskan Continental Shelf, Principal Investigators’ Reports, July-September 1975, Volume 1. NOAA Environmental Research Laboratories, Boulder, Colorado. pp. 77-78.

Crawford, J. and Quakenbush, L. 2013. Ringed seals and climate change: early predictions versus recent observations in Alaska. Oral presentation by Justin Crawfort, 28th Lowell Wakefield Fisheries Symposium, March 26-29. Anchorage, AK. http://seagrant.uaf.edu/conferences/2013/wakefield-arctic-ecosystems/program.php

Crawford, J.A., Quakenbush, L.T. & Citta, J.J. 2015. A comparison of ringed and bearded seal diet, condition and productivity between historical (1975–1984) and recent (2003–2012) periods in the Alaskan Bering and Chukchi seas. Progress in Oceanography 136:133-150.

Crockford, S.J. 2015. The Arctic Fallacy: Sea Ice Stability and the Polar Bear. Global Warming Policy Foundation Briefing Paper 16. London. Available at http://www.thegwpf.org/susan-crockford-the-arctic-fallacy-2/

Crockford, S.J. 2017. Testing the hypothesis that routine sea ice coverage of 3-5 mkm2 results in a greater than 30% decline in population size of polar bears (Ursus maritimus). PeerJ Preprints 2 March 2017. Doi: 10.7287/peerj.preprints.2737v3 Open access. https://doi.org/10.7287/peerj.preprints.2737v3

DeMaster, D.P., Kingsley, M.C.S. & Stirling, I. 1980. A multiple mark and recapture estimate applied to polar bears. Canadian Journal of Zoology 58:633-638.

Derocher, A.E., and Stirling, I. 1992. The population dynamics of polar bears in western Hudson Bay. In Wildlife 2001: populations. Edited by D. R. McCullough and R.H. Barrett .
Elsevier Applied Science, London. pp. 1150- 1 159.

Derocher, A.E., and Stirling, I. 1995a. Estimation of polar bear population size and survival in western Hudson Bay. Journal of Wildlife Management 59: 215-221.

Derocher, A.E., and Stirling, I. 1995b. Temporal variation in reproduction and body mass of polar bears in western Hudson Bay. Canadian Journal of Zoology 73: 1657-1665.

Derocher, A.E., and Stirling, I. 1996. Aspects of survival in juvenile polar bears. Canadian Journal of Zoology 74:1246-1252.

Ferguson, S.H., Stirling, I. and McLoughlin, P. 2005. Climate change and ringed seal (Phoca hispida) recruitment in Western Hudson Bay. Marine Mammal Science 21: 121–135.

Harvey, J.A., van den Berg, D., Ellers, J., Kampen, R., Crowther, T.W., Roessingh, P., Verheggen, B., Nuijten, R. J. M., Post, E., Lewandowsky, S., Stirling, I., Balgopal, M., Amstrup, S.C., and Mann, M.E. 2017. Internet blogs, polar bears, and climate-change denial by proxy. Bioscience. DOI: 10.1093/biosci/bix133 pdf here. Supplementary info here.

Harwood, L.A., Smith, T.G. and Melling, H. 2000. Variation in reproduction and body condition of the ringed seal (Phoca hispida ) in western Prince Albert Sound, NT, Canada, as assessed through a harvest-based sampling program. Arctic 53:422 – 431.

Harwood, L.A., Smith, T.G., Melling, H., Alikamik, J. and Kingsley, M.C.S. 2012. Ringed seals and sea ice in Canada’s western Arctic: harvest-based monitoring 1992-2011. Arctic 65:377-390.

Hunter, C.M., Caswell, H., Runge, M.C., Regehr, E.V., Amstrup, S.C. and Stirling, I. 2010. Climate change threatens polar bear populations: a stochastic demographic analysis. Ecology 91:2883-2897.

Kovacs, K.M. 2015. Pagophilus groenlandicus. The IUCN Red List of Threatened Species 2015: e.T41671A45231087. http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T41671A45231087.en

Kovacs, K.M. 2016a. Cystophora cristata. The IUCN Red List of Threatened Species 2016: e.T6204A45225150. http://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T6204A45225150.en

Kovacs, K.M. 2016b. Erignathus barbatus. The IUCN Red List of Threatened Species 2016: e.T8010A45225428. Available online http://www.iucnredlist.org/details/full/8010/0

Lowry, L. 2016. Pusa hispida. The IUCN Red List of Threatened Species 2016, e.T41672A45231341. Available online http://www.iucnredlist.org/details/full/61382318/0

Ramsay, M.A. and Stirling, I. 1988. Reproductive biology and ecology of female polar bears (Ursus maritimus). Journal of Zoology London 214:601-624.

Ramseier, R.O., Vant, M.R., Arsenault, L.D., Gray, L., Gray, R.B., and Chudobiak, W.J. 1975. Distribution of the ice thickness in the Beaufort Sea. Beaufort Sea Technical Report #30. Canada Dept. of Environment, Victoria, B.C. Available online.

Smith, T.G. 1987. The ringed seal, Phoca hispida, of the Canadian Western Arctic. Canadian Bulletin of Fisheries and Aquatic Sciences 216. Department of Fisheries and Oceans, Ottawa.

Smith, T.G. and Stirling, I. 1978. Variation in the density of ringed seal (Phoca hispida) birth lairs in the Amundsen Gulf, Northwest Territories. Canadian Journal of Zoology 56:1066–1071.

Stirling, I. 2002. Polar bears and seals in the eastern Beaufort Sea and Amundsen Gulf: a synthesis of population trends and ecological relationships over three decades. Arctic 55 (Suppl. 1):59-76.

Stirling I. 2005. Reproductive rates of ringed seals and survival of pups in northwestern Hudson Bay, Canada, 1991–2000. Polar Biology 28(5):381–387 DOI 10.1007/s00300-004-0700-7.

Stirling, I. and Lunn, N.J. 1997. Environmental fluctuations in arctic marine ecosystems as reflected by variability in reproduction of polar bears and ringed seals. In Ecology of Arctic Environments, Woodin, S.J. and Marquiss, M. (eds), pg. 167-181. Blackwell Science, UK.

Stirling, I., Andriashek, D., Latour, P.B. and Calvert, W. 1975a. Distribution and abundance of polar bears in the Eastern Beaufort Sea. Beaufort Sea Tech. Report #2, Dept. Environment, Victoria, B.C.

Stirling, I., Archibald, R. and DeMaster, D. 1975b. Distribution and abundance of seals in the Eastern Beaufort Sea. Beaufort Sea Tech. Report #1, Dept. Environment, Victoria, B.C.

Stirling, I, Cleator, H. and Smith, T.G. 1981. Marine mammals. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 45-58. Canadian Wildlife Service Occasional Paper No. 45. Ottawa.

Stirling, I, Kingsley, M. and Calvert, W. 1982. The distribution and abundance of seals in the eastern Beaufort Sea, 1974–79. Canadian Wildlife Service Occasional Paper 47. Edmonton.

Stirling, I., Richardson, E., Thiemann, G.W. and Derocher, A.E. 2008. Unusual predation attempts of polar bears on ringed seals in the southern Beaufort Sea: possible significance of changing spring ice conditions. Arctic 61:14-22.

US Fish & Wildlife Service (USFWS). 2012a. Threatened status for the Arctic, Okhotsk and Baltic subspecies of the ringed seal. Federal Register 77:76706–76738.

US Fish & Wildlife Service (USFWS). 2012b. Threatened status for the Beringia and Okhotsk distinct population segments of the Erignathus barbatus nauticus subspecies of the bearded seal. Federal Register 77:76740–76768.

Spring in the Arctic is April-June (Pilfold et al. 2015). As late April is the peak of this critical spring feeding period for most polar bear populations, this is when sea ice conditions are also critical. This year, as has been true since 1979, that sea ice coverage is abundant across the Arctic for seals that are giving birth and mating at this time as well as for polar bears busy feeding on young seals and mating.

Below is a chart of sea ice at 25 April 2018, showing sea ice in all PBSG polar bear subpopulation regions:

Some Arctic subregions below, in detail.

Canada (from CIS)

Weekly stage of development, by area (from the west): brown is very thick, multiyear ice (2-5m thick) and dark green is thick first year ice (>1.2m). Note the area of shallow water (i.e. the continental shelf, <300m) is very narrow along the north coast of Alaska) and how close multiyear ice is to shore this year (seals and bears do best in first year ice):

Barents Sea (from NIS)

Compare the ice coverage above to what it was in the spring of 2015, just before the most recent survey that showed numbers around Svalbard (and likely beyond) had risen by 42% (Aars et al. 2017; Crockford 2017, 2018).

References

Aars, J., Marques,T.A, Lone, K., Anderson, M., Wiig, Ø., Fløystad, I.M.B., Hagen, S.B. and Buckland, S.T. 2017. The number and distribution of polar bears in the western Barents Sea. Polar Research 36:1, 1374125. https://www.tandfonline.com/doi/full/10.1080/17518369.2017.1374125

Crockford, S.J. 2017. Testing the hypothesis that routine sea ice coverage of 3-5 mkm2 results in a greater than 30% decline in population size of polar bears (Ursus maritimus). PeerJ Preprints 2 March 2017. Doi: 10.7287/peerj.preprints.2737v3 Open access. https://doi.org/10.7287/peerj.preprints.2737v3

Crockford, S.J. 2018. State of the Polar Bear Report 2017. Global Warming Policy Foundation Report #29. London. pdf here.

Pilfold, N. W., Derocher, A. E., Stirling, I. and Richardson, E. 2015. Multi-temporal factors influence predation for polar bears in a changing climate. Oikos 124: 1098-1107. http://onlinelibrary.wiley.com/doi/10.1111/oik.02000/abstract

Sea ice habitat for polar bears has not become progressively worse each year during their season of critical feeding and mating, as some scaremongers often imply. It’s true that absolute extent of Arctic ice is lower this spring than it was in 1979. However, according to NSIDC Masie figures, polar bear habitat at mid-May registers about 12 million km2, just as it did in 2006 (although it is distributed a little differently); other data show spring extent has changed little since a major decline occurred in 1989, despite ever-rising CO2 levels.

In other words, there has been virtually no change in sea ice cover over the last 12 years, despite the fact that atmospheric CO2 has now surpassed 410 parts per million, a considerable and steady increase over levels in 2006 which were about 380 ppm (see below, from the Scripps Oceanographic Laboratory, included in the Washington Post story 3 May 2018):

Not only that, but if rising CO2 levels were responsible for the decline of sea ice and implied effects on polar bears since 1979 (when CO2 levels were around 340 ppm), why has spring ice extent been so variable since 1989 (when the first big decline occurred) but so little changed overall since then? See the NSIDC graph below for April:

This year on day 134 (14 May), global ice cover registered 12.3 mkm2:

In 2016 on the same day, the overall extent was much the same but there was more ice in the Chukchi and Bering Seas and less in the eastern Beaufort:

More close-up charts of different regions below for 2018 vs. 2016, showing more detail.

Here’s the close-up for Canada on the same date (14 May 2018):

Compare the above to 2016 a day earlier (13 May), below:

This year, virtually all of Hudson Bay, Hudson Strait, Foxe Basin and Davis Strait were covered in thick first year ice (>1.2m thick) by the first week in May:

Compare the above to conditions in 2016 the first week of May, when medium first year ice (70-120 cm thick) was more extensive and widening shore leads were prominent:

In Western Canada and eastern Alaska this year, most of the region was covered by thick, concentrated, multiyear ice by the first week in May:

Compare the above to condition in 2016 in the same area, when a major polynya (open water) was beginning to form due to prevailing winds at the time:

Eastern Arctic Canada in the first week of May this year was a mix of thick, multiyear ice and thick first year ice (>1.2 m):

Compare the above to Eastern Arctic Canada in the first week of May 2016 (below), was also a mix of thick, multiyear ice and thick first year ice (>1.2 m) but more thin and medium first year ice and more open water:

In the eastern Atlantic, ice in the Barents Sea was quite extensive at the end of April:

However, by 14 May this year the ice was breaking up between Svalbard and Franz Josef Land:

Back in 2016 at about the same date, there was more concentrated ice between the two archipelagos but less concentrated pack ice northeast of Nova Zemlya (that long skinny island east of Franz Josef Land):

On-going polar bear research around Svalbard shows no significant negative effects of lower-than-average spring sea ice in this region (Crockford 2018).

Conclusion

There was still plenty of ice in the spring of 2018 to meet the needs of polar bears. There has been little material difference in polar bear sea ice habitat during April/May — the most critical time period for polar bears — since 2006. Moreover, there has been somewhat less ice during this period in recent years than in 1979-1988 but little change since 1989, suggesting that spring sea ice levels are not particularly sensitive to rising atmospheric CO2 levels. Regardless, there is no evidence that this slight change in spring ice extent has caused any negative effects on polar bear health and survival: virtually all efforts to date have been focused on making correlations with reduced summer sea ice.

References

Crockford, S.J. 2018. State of the Polar Bear Report 2017. Global Warming Policy Foundation Report #29. London. Pdf here: State of the Polar Bear Report 2017

Polar bears in virtually all regions will now have finished their intensive spring feeding, which means sea ice levels are no longer an issue. A few additional seals won’t make much difference to a bear’s condition at this point, except perhaps for young bears that haven’t had a chance to feed as heavily as necessary over the spring due to inexperience or competition.

The only seals available on the ice for polar bears to hunt in early July through October are predator-savvy adults and subadults. But since the condition of the sea ice makes escape so much easier for the seals to escape, most bears that continue to hunt are unsuccessful – and that’s been true since the 1970s. So much for the public hand-wringing over the loss of summer sea ice on behalf of polar bear survival!

Polar bears in most areas of the Arctic are at their fattest by late June. They are well prepared to go without food for a few months if necessary – a summer fast is normal for polar bears, even for those that spend their time on the sea ice.

Putting on hundreds of pounds of fat in the spring to last through periods of food scarcity later in the year (at the height of summer and over the winter) is the evolutionary adaptation that has allowed polar bears to live successfully in the Arctic.

The fact is, most ringed seals (the primary prey species of polar bears worldwide) move into open water to feed after they have completed their annual molt, which occurs by late June to mid-July for adults and subadults. Newborn pups leave the ice soon after being weaned, usually by the end of May in southern regions (like Hudson Bay) and by late June in the Canadian Arctic Archipelago (Kelly et al. 2010; Smith 1975, 1987; Whiteman et al. 2015).

Adult and subadult ringed seals do most of their feeding in open water over the ice-free season in summer (Crawford et al. 2015; Rode et. al. 2014, 2018).

Thus, the most abundant prey of polar bears is essentially unavailable after late June (and earlier than that in Hudson Bay and Davis Strait). After that time, only predator-savvy adult and subadult ringed seals haul out on the ice.

Adults and subadults of the similarly-distributed but much larger (and less abundant) bearded seal tend to remain with the ice over the summer (Cameron et al. 2010:11-12) and are most likely to be available to polar bears that remain on the sea ice over the summer throughout the Arctic. Some adult harp seals (an abundant, strictly North Atlantic species) may also be available to bears on the pack ice in Baffin Bay and Davis Strait, as well in the northern sections of the Barents and Kara Seas, and northern East Greenland (Sergeant 1991).

However, research on polar bear feeding has shown that from late June to October, bears are rarely successful at catching seals because broken and melting ice affords so many escape routes for the seals. Bears may stalk the seals but they often get away (see video snapshot and video below)

[Full video clip below]

The facts on this feeding pattern were documented back in the 1970s and 1980s and are assumed by polar bear biologists to be true today (Derocher et al. 2002; Stirling 1974; Stirling and Øritsland 1995; Obbard et al. 2016; Pilfold et al. 2015).

They just don’t say so in public.

This intensive spring feeding phenomenon means that virtually all polar bears residing in so-called Seasonal and Divergent ecoregions (see above green and purple areas) – predicted to be extirpated by 2050, according to documents supporting the ESA listing of polar bears as ‘threatened’ with extinction (Amstrup et al. 2007; USFWS 2008) – effectively fast from late spring to early fall whether they spend this time on land or on the sea ice.

Which means we should indeed be worried if there is NO sea ice by the end of May, or even late June, across the Arctic but that’s nowhere near happening. There was perhaps slightly less ice this year at 21 June than in the early 1980s but a bit less is not the same as none.

To imply that slightly less ice at this time of year impacts polar bears and seals suggests they are incapable of moving laterally in response to changing conditions – which is clearly not true.

For example, many ringed seals and polar bears of the Southern Beaufort moved west to the Chukchi and Bering Seas in 1974 and 1975 when thick spring ice made staying in the Beaufort untenable (Burns et al. 1975; Stirling et al. 1975a,b; Stirling et al. 1982, Stirling et al. 1985:75).

If bears and seals were able to move massive distances to avoid excessive ice in the Beaufort in the 1970s, they can certainly move short distances in response to less ice now. Some might call it adaptation but flexibility is also an apt description.

So much for the Save our Sea Ice campaign run by Steven Amstrup and the drama queens at Polar Bears International, scheduled for 15 July.

Here is what PBI claimed two years ago:

“This summer [2016], the sea ice retreat could well break records, impacting polar bears, other wildlife, and people too. Sea ice loss in the month of May covered an area three times larger than the state of California compared with the historical average.” [my bold]

However, by July 15, few bears will be eating seals even if they remain on the ice – and most bears will have effectively stopped feeding many weeks before that. There is no evidence that the “sea ice loss” in May 2016 had any effect on polar bears whatsoever and the same will be true this year.

Knowing the facts means you won’t be taken in by the hype. This year, PBI are focusing on summer ice lows (in September) and the recent “low” extents reached in the four previous winters, as if there is any evidence that a bit less ice in winter has any effect on polar bear health and survival (there is not).

Sea ice maps (NSIDC Masie) below for the end of May 2016 vs. 2018:

And now (2 July 2018)…

References

Amstrup, S.C., Marcot, B.G. and Douglas, D.C. 2007. Forecasting the rangewide status of polar bears at selected times in the 21st century. Administrative Report, US Geological Survey. Reston, Virginia.

Burns, J. J., Fay, F. H., and Shapiro, L.H. 1975. The relationships of marine mammal distributions, densities, and activities to sea ice conditions (Quarterly report for quarter ending September 30, 1975, projects #248 and 249), pp. 77-78 in Environmental Assessment of the Alaskan Continental Shelf, Principal Investiagors’ Reports. July-September 1975, Volume 1. NOAA, Environmental Research Laboratories, Boulder Colorado. [available online]

Cameron, M. F., Bengtson, J. L., Boveng, J. K., Jansen, J. K., Kelly, B. P., Dahle, S. P., Logerwell, E. A., Overland, J. E., Sabine, C. L., Waring, G. T. and Wilder, J. M. 2010. Status review of the bearded (Erignatha barbatus). NOAA Technical Memorandum NMFS-AFSC-211.

Crawford, J.A., Quakenbush, L.T. & Citta, J.J. 2015. A comparison of ringed and bearded seal diet, condition and productivity between historical (1975–1984) and recent (2003–2012) periods in the Alaskan Bering and Chukchi seas. Progress in Oceanography 136:133-150.

Derocher, A.E.,Wiig,Ø. and Andersen, M. 2002. Diet composition of polar bears in Svalbard and the western Barents Sea. Polar Biology 25 (6): 448–452.

Kelly, B. P., Bengtson, J. L., Boveng, P. L., Cameron, M. F., Dahle, S. P., Jansen, J. K., Logerwell, E. A., Overland, J. E., Sabine, C. L., Waring, G. T. and Wilder, J. M. 2010. Status review of the ringed seal (Phoca hispida). NOAA Technical Memorandum NMFS-AFSC-212.

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, in press. 10.1139/AS-2015-0027

Pilfold, N. W., Derocher, A. E., Stirling, I. and Richardson, E. 2015. Multi-temporal factors influence predation for polar bears in a changing climate. Oikos 124(8):1098-1107. http://onlinelibrary.wiley.com/doi/10.1111/oik.02000/abstract

Rode, K.D., Regehr, E.V., Douglas, D., Durner, G., Derocher, A.E., Thiemann, G.W., and Budge, S. 2014. Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations. Global Change Biology 20(1):76-88.

Rode, K.D., Wilson, R.R., Douglas, D.C., Muhlenbruch, V., Atwood, T.C., Regehr, E.V., Richardson, E.S., Pilfold, N.W., Derocher, A.E., Durner, G.M., Stirling, I., Amstrup, S.C., St. Martin, M., Pagano, A.M. and Simac, K. 2018. Spring fasting behavior in a marine apex predator provides an index of ecosystem productivity. Global Change Biology.

Sergeant, D.E. 1991. Harp Seals, Man and Ice. Canadian Special Publication of Fisheries and Aquatic Sciences 114. Fisheries and Oceans Canada, Ottawa.

Smith, T. G. 1975. Ringed seals in James Bay and Hudson Bay: population estimates and catch statistics. Arctic 28:170-182.

Smith, T. G. 1987. The ringed seal, Phoca hispida,of the Canadian Western Arctic. Canadian Bulletin of Fisheries and Aquatic Sciences 216, Ottawa.

Stirling, I. and Øritsland, N. A. 1995. Relationships between estimates of ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic. Canadian Journal of Fisheries and Aquatic Sciences 52:2594–2612.

Stirling, I., Andriashek, D., Latour, P.B. and Calvert, W. 1975a. Distribution and abundance of polar bears in the Eastern Beaufort Sea. Beaufort Sea Technical Report #2, Department of the Environment, Victoria, B.C.

Stirling, I., Archibald, R. and DeMaster, D. 1975b. Distribution and abundance of seals in the Eastern Beaufort Sea. Beaufort Sea Technical Report #1, Department of the Environment, Victoria, B.C.

Stirling, I, Kingsley, M. and Calvert, W. 1982. The distribution and abundance of seals in the eastern Beaufort Sea, 1974–79. Canadian Wildlife Service Occasional Paper 47. Edmonton.

Stirling, I., Schweinsburg, R.E., Kolenasky, G.B., Juniper, I., Robertson, R.J., Luttich, S. and Calvert, W. 1985. Research on polar bears in Canada 1978-80. In: Anonymous, 1985, Proceedings of the 8th meeting of the Polar Bear Specialists Group IUCN/SSC, 15-19 January 1981, Oslo, Norway. Gland, Switzerland and Cambridge UK, IUCN, pp. 71-98.

US Fish and Wildlife Service. 2008. Determination of threatened status for the polar bear (Ursus maritimus) throughout its range. Federal Register 73(95):28212-28303.

Whiteman, J.P., Harlow, H.J., Durner, G.M., Anderson-Sprecher, Albeke, S.E., Regehr, E.V., Amstrup, S.C., and Ben-David, M. 2015. Summer declines in activity and body temperature offer polar bears limited energy savings. Science 349 (6245):295-298.

Summer sea ice loss is finally ramping up: first year is disappearing, as it has done every year since ice came to the Arctic millions of years ago. But critical misconceptions, fallacies, and disinformation abound regarding Arctic sea ice and polar bear survival. Ahead of Arctic Sea Ice Day (15 July), here are 10 fallacies that teachers and parents especially need to know about.

The cartoon above was done by Josh: you can drop off the price of a beer (or more) for his efforts here.

As always, please contact me if you would like to examine any of the references included in this post. These references are what make my efforts different from the activist organization Polar Bears International. PBI virtually never provide references within the content it provides, including material it presents as ‘educational’. Links to previous posts of mine that provide expanded explanations, images, and additional references are provided.

Sea ice background: extent over the last year

Summer sea ice minimum 2018 (from NSIDC):

Winter sea ice maximum 2019:

Sea ice at 7 July 2019: early summer extent

Despite the fact that 2019 had the 2nd lowest extent for the month of June since 1979, by early July, there was still ice adjacent to all major polar bear denning areas across the Arctic. In many regions, pregnant females that give birth on land in December come ashore in summer and stay until their newborn cubs are old enough to return with them to the ice the following spring. See Andersen et al. 2012; Ferguson et al. 2000; Garner et al. 1994; Jonkel et al. 1978; Harington 1968; Kochnev 2018; Kolenosky and Prevett 1983; Larsen 1985; Olson et al. 2017; Richardson et al. 2005; Stirling and Andriashek 1992.

Ten fallacies and disinformation about sea ice

1. ‘Sea ice is to the Arctic as soil is to a forest‘. False: this all-or-nothing analogy is an specious comparison. In fact, Arctic sea ice is like a big wetland pond that dries up a bit every summer, where the amount of habitat available to sustain aquatic plants, amphibians and insects is reduced but does not disappear completely. Wetland species are adapted to this habitat: they are able to survive the reduced water availability in the dry season because it happens every year. Similarly, sea ice will always reform in the winter and stay until spring. During the two million or so years that ice has formed in the Arctic, there has always been ice in the winter and spring (even in warmer Interglacials than this one). Moreover, I am not aware of a single modern climate model that predicts winter ice will fail to develop over the next 80 years or so. See Amstrup et al. 2007; Durner et al. 2009; Gibbard et al. 2007; Polak et al. 2010; Stroeve et al. 2007.

2. Polar bears need summer sea ice to survive.  False: polar bears that have fed adequately on young seals in the early spring can live off their fat for five months or more until the fall, whether they spend the summer on land or the Arctic pack ice. Polar bears seldom catch seals in the summer because only predator-savvy adult seals are available and holes in the pack ice allow the seals many opportunities to escape (see the BBC video below). Polar bears and Arctic seals truly require sea ice from late fall through early spring only. See Crockford 2017, 2019; Hammill and Smith 1991:132; Obbard et al. 2016; Pilfold et al. 2016; Stirling 1974; Stirling and Øritsland 1995; Whiteman et al. 2015.

3. Ice algae is the basis for all Arctic life. Only partially true: plankton also thrives in open water during the Arctic summer, which ultimately provides food for the fish species that ringed and bearded seals depend upon to fatten up before the long Arctic winter. Recent research has shown that less ice in summer has improved ringed and bearded seal health and survival over conditions that existed in the 1980s (when there was a shorter ice-free season and fewer fish to eat): as a consequence, abundant seal populations have been a boon for the polar bears that depend on them for food in early spring. For example, despite living with the most profound decline of summer sea ice in the Arctic polar bears in the Barents Sea around Svalbard are thriving, as are Chukchi Sea polar bears – both contrary to predictions made in 2007 that resulted in polar bears being declared ‘threatened’ with extinction under the Endangered Species Act. See Aars 2018; Aars et al. 2017; Amstrup et al. 2007; Arrigo and van Dijken 2015; Crawford and Quadenbush 2013; Crawford et al. 2015; Crockford 2017, 2019; Frey et al. 2018; Kovacs et al. 2016; Lowry 2016; Regehr et al. 2018; Rode and Regehr 2010; Rode et al. 2013, 2014, 2015, 2018.

4. Open water in early spring as well as summer ice melt since 1979 are unnatural and detrimental to polar bear survival. False: melting ice is a normal part of the seasonal changes in the Arctic. In the winter and spring, a number of areas of open water appear because wind and currents rearrange the pack ice – this is not melt, but rather normal polynya formation and expansion. Polynyas and widening shore leads provide a beneficial mix of ice resting platform and nutrient-laden open water that attracts Arctic seals and provides excellent hunting opportunities for polar bears. The map below shows Canadian polynyas and shore leads known in the 1970s : similar patches of open water routinely develop in spring off eastern Greenland and along the Russian coast of the Arctic Ocean. See Dunbar 1981; Grenfell and Maykut 1977; Hare and Montgomery 1949; Smith and Rigby 1981; Stirling and Cleator 1981;  Stirling et al. 1981, 1993.

Recurring polynyas and shore leads in Canada known in the 1970s. From Smith and Rigby 1981

5. Climate models do a good job of predicting future polar bear habitat. False: My recent book, The Polar Bear Catastrophe That Never Happened, explains that the almost 50% decline in summer sea ice that was not expected until 2050 actually arrived in 2007, where it has been ever since (yet polar bears are thriving). That is an extraordinarily bad track record of sea ice prediction. Also, contrary to predictions made by climate modelers, first year ice has already replaced much of the multi-year ice in the southern and eastern portion of the Canadian Arctic Archipelago, to the benefit of polar bears. See also ACIA 2005; Crockford 2017, 2019; Durner et al. 2009; Hamilton et al. 2014; Heide-Jorgensen et al. 2012; Perovich et al. 2018; Stern and Laidre 2016; Stroeve et al. 2007; SWG 2016; Wang and Overland 2012.

Simplified predictions vs. observations up to 2007 provided by Stroeve et al. 2007 (courtesy Wikimedia). Sea ice hit an even lower extent in 2012 and all years since then have been below predicted levels.

6. Sea ice is getting thinner and that’s a problem for polar bears.  False: First year ice (less than about 2 metres thick) is the best habit for polar bears because it is also the best habitat for Arctic seals. Very thick multi-year ice that has been replaced by first year ice that melts completely every summer creates more good habitat for seals and bears in the spring, when they need it the most. This has happened especially in the southern and eastern portions of the Canadian Arctic Archipelago (see ice chart below from Sept 2016). Because of such changes in ice thickness, the population of polar bears in Kane Basin (off NW Greenland) has more than doubled since the late 1990s. See Atwood et al. 2016; Durner et al. 2009; Lang et al. 2017; Stirling et al. 1993; SWG 2016.

7. Polar bears in Western and Southern Hudson Bay are most at risk of extinction due to global warming. False: Ice decline in Hudson Bay has been among the lowest across the Arctic. Sea ice decline in Hudson Bay (see graphs below) has been less than one day per year since 1979 compared to more than 4 days per year in the Barents Sea. Hudson Bay ice decline also uniquely happened as a sudden step-change in 1998: there has not been a slow and steady decline. Since 1998, the ice-free season in Western Hudson Bay has been about 3 weeks longer overall than it was in the 1980s but has not become any longer over the last 20 years despite declines in total Arctic sea ice extent or increased carbon dioxide emissions. See Castro de la Guardia et al. 2017; Regehr et al. 2016.

Loss of summer sea ice per year, 1979-2014. From Regehr et al. 2016.

8. Breakup of sea ice in Western Hudson Bay now occurs three weeks earlier than it did in the 1980s. False: Breakup now occurs about 2 weeks earlier in summer than it did in the 1980s. The total length of the ice-free season is now about 3 weeks longer (with lots of year-to-year variation). See Castro de la Guardia et al. 2017; Cherry et al. 2013; Lunn et al. 2016; and vidoe below, showing the first bear spotted off the ice at Cape Churchill, Western Hudson Bay, on 5 July 2019 – fat and healthy after eating well during the spring:

9. Winter sea ice has been declining since 1979, putting polar bear survival at risk. Only partially true: while sea ice in winter (i.e. March) has been declining gradually since 1979 (see graph below from NOAA), there is no evidence to suggest this has negatively impacted polar bear health or survival, as the decline has been quite minimal. The sea ice chart at the beginning of this post shows that in 2019 there was plenty of ice remaining in March to meet the needs of polar bears and their primary prey (ringed and bearded seals), despite it being the 7th lowest since 1979.

10. Experts say that with 19 different polar bear subpopulations across the Arctic, there are “19 sea ice scenarios playing out“ (see also here), implying this is what they predicted all along. False: In order to predict the future survival of polar bears, biologists at the US Geological Survey in 2007 grouped polar bear subpopulations with similar sea ice types (which they called ‘polar bear ecoregions,’ see map below). Their predictions of polar bear survival were based on assumptions of how the ice in these four sea ice regions would change over time (with areas in purple and green being similarly extremely vulnerable to effects of climate change). However, it turns out that there is much more variation than they expected: contrary to predictions, the Barents Sea has had a far greater decline in summer ice extent than any other region, and both Western and Southern Hudson Bay have had relatively little (see #7). See Amstrup et al. 2007; Crockford 2017, 2019; Durner et al. 2009; Atwood et al. 2016; Regehr et al. 2016.

References

Aars, J. 2018. Population changes in polar bears: protected, but quickly losing habitat. Fram Forum Newsletter 2018. Fram Centre, Tromso. Download pdf here (32 mb).

Aars, J., Marques,T.A, Lone, K., Anderson, M., Wiig, Ø., Fløystad, I.M.B., Hagen, S.B. and Buckland, S.T. 2017. The number and distribution of polar bears in the western Barents Sea. Polar Research 36:1. 1374125. doi:10.1080/17518369.2017.1374125

ACIA 2005. Arctic Climate Impact Assessment: Scientific Report. Cambridge University Press. See their graphics package of sea ice projections here.

AMAP 2017. [ACIA 2005 update]. Snow, Water, Ice, and Permafrost in the Arctic Summary for Policy Makers (Second Impact Assessment). Arctic Monitoring and Assessment Programme, Oslo. pdf here.

Amstrup, S.C. 2003. Polar bear (Ursus maritimus). In Wild Mammals of North America, G.A. Feldhamer, B.C. Thompson and J.A. Chapman (eds), pg. 587-610. Johns Hopkins University Press, Baltimore.

Amstrup, S.C., Marcot, B.G. & Douglas, D.C. 2007. Forecasting the rangewide status of polar bears at selected times in the 21st century. US Geological Survey. Reston, VA. Pdf here

Andersen, M., Derocher, A.E., Wiig, Ø. and Aars, J. 2012. Polar bear (Ursus maritimus) maternity den distribution in Svalbard, Norway. Polar Biology 35:499-508.

Arrigo, K.R. and van Dijken, G.L. 2015. Continued increases in Arctic Ocean primary production. Progress in Oceanography 136: 60-70. http://dx.doi.org/10.1016/j.pocean.2015.05.002

Atwood, T.C., Marcot, B.G., Douglas, D.C., Amstrup, S.C., Rode, K.D., Durner, G.M. et al. 2016. Forecasting the relative influence of environmental and anthropogenic stressors on polar bears. Ecosphere 7(6): e01370.

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/

Cherry, S.G., Derocher, A.E., Thiemann, G.W., Lunn, N.J. 2013. Migration phenology and seasonal fidelity of an Arctic marine predator in relation to sea ice dynamics. Journal of Animal Ecology 82:912-921. http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12050/abstract

Crawford, J. and Quakenbush, L. 2013. Ringed seals and climate change: early predictions versus recent observations in Alaska. Oral presentation by Justin Crawfort, 28^th Lowell Wakefield Fisheries Symposium, March 26-29. Anchorage, AK. Abstract below, find pdf here:http://seagrant.uaf.edu/conferences/2013/wakefield-arctic-ecosystems/program.php

Crawford, J.A., Quakenbush, L.T. and Citta, J.J. 2015. A comparison of ringed and bearded seal diet, condition and productivity between historical (1975–1984) and recent (2003–2012) periods in the Alaskan Bering and Chukchi seas. Progress in Oceanography 136:133-150.

Crockford, S.J. 2017. Testing the hypothesis that routine sea ice coverage of 3-5 mkm2 results in a greater than 30% decline in population size of polar bears (Ursus maritimus). PeerJ Preprints 19 January 2017. Doi: 10.7287/peerj.preprints.2737v1 Open access. https://peerj.com/preprints/2737/

Crockford, S.J. 2019. The Polar Bear Catastrophe That Never Happened. Global Warming Policy Foundation, London. Available in paperback and ebook formats.

Derocher, A.E., Wiig, Ø., and Andersen, M. 2002. Diet composition of polar bears in Svalbard and the western Barents Sea. Polar Biology 25 (6): 448-452. http://link.springer.com/article/10.1007/s00300-002-0364-0

Dunbar, M.J. 1981. Physical causes and biological significance of polynyas and other open water in sea ice. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 29-43. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Durner, G.M. and Amstrup, S.C. 1996. Mass and body-dimension relationships of polar bears in northern Alaska. Wildlife Society Bulletin 24(3):480-484.

Durner, G.M., Douglas, D.C., Nielson, R.M., Amstrup, S.C., McDonald, T.L., et al. 2009. Predicting 21st-century polar bear habitat distribution from global climate models. Ecology Monographs 79: 25–58.

Ferguson, S. H., Taylor, M. K., Rosing-Asvid, A., Born, E.W. and Messier, F. 2000. Relationships between denning of polar bears and conditions of sea ice. Journal of Mammalogy 81: 1118-1127.

Frey, K.E., Comiso, J.C., Cooper, L.W., Grebmeier, J.M., and Stock, L.V. 2018. Arctic Ocean primary productivity: the response of marine algae to climate warming and sea ice decline. NOAA Arctic Report Card: Update for 2018.  https://arctic.noaa.gov/Report-Card/Report-Card-2018/ArtMID/7878/ArticleID/778/Arctic-Ocean-Primary-Productivity-The-Response-of-Marine-Algae-to-Climate-Warming-and-Sea-Ice-Decline

Garner, G.W., Belikov, S.E., Stishov, M.S., Barnes, V.G., and Arthur, S.M. 1994. Dispersal patterns of maternal polar bears from the denning concentration on Wrangel Island. International Conference on Bear Research and Management 9(1):401-410.

Gibbard, P. L., Boreham, S., Cohen, K. M. and Moscariello, A. 2005. Global chronostratigraphical correlation table for the last 2.7 million years, modified/updated 2007. Boreas 34(1) unpaginated and University of Cambridge, Cambridge Quaternary http://www.qpg.geog.cam.ac.uk/

Grenfell, T.C. and Maykut, G. A. 1977. The optical properties of ice and snow in the Arctic Basin. Journal of Glaciology 18 (80):445-463. http://www.ingentaconnect.com/contentone/igsoc/jog/1977/00000018/00000080/art00008

Hamilton, S.G., Castro de la Guardia, L., Derocher, A.E., Sahanatien, V., Tremblay, B. and Huard, D. 2014. Projected polar bear sea ice habitat in the Canadian Arctic Archipelago. PLoS One 9(11):e113746.

Hammill, M.O. and Smith T.G. 1991. The role of predation in the ecology of the ringed seal in Barrow Strait, Northwest Territories, Canada. Marine Mammal Science 7:123–135.

Hare, F.K. and Montgomery, M.R. 1949. Ice, Open Water, and Winter Climate in the Eastern Arctic of North America: Part II. Arctic 2(3):149-164. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3985 Pdf here.

[see also: Hare, F.K. and Montgomery, M.R. 1949. Ice, Open Water, and Winter Climate in the Eastern Arctic of North America: Part I. Arctic 2(2):79-89. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3976 ]

Harington, C. R. 1968. Denning habits of the polar bear (Ursus maritimus Phipps). Canadian Wildlife Service Report Series 5.

Heide-Jorgensen, M.P., Laidre, K.L., Quakenbush, L.T. and Citta, J.J. 2012. The Northwest Passage opens for bowhead whales. Biology Letters 8(2):270-273. doi:10.1098/rsbl.2011.0731

Jonkel, C., Land, E. and Redhead, R. 1978. The productivity of polar bears () in the southeastern Baffin Island area, Northwest Territories. Canadian Wildlife Service Progress Notes 91.

Kochnev, A.A. 2018. Distribution and abundance of polar bear (Ursus maritimus) dens in Chukotka (based on inquiries of representatives of native peoples). Biology Bulletin 45 (8):839-846.

Kolenosky, G.B. and Prevett, J.P. 1983. Productivity and maternity denning of polar bears in Ontario. Bears: Their Biology and Management 5:238-245.

Kovacs, K.M. 2016. Erignathus barbatus. The IUCN Red List of Threatened Species 2016: e.T8010A45225428. http://www.iucnredlist.org/details/full/8010/0

Lang, A., Yang, S. and Kaas, E. 2017. Sea ice thickness and recent Arctic warming Geophysical Research Letters. DOI: 10.1002/2016GL071274

Larsen, T. 1985. Polar bear denning and cub production in Svalbard, Norway. Journal of Wildlife Management 49:320-326.

Lowry, L. 2016. Pusa hispida. The IUCN Red List of Threatened Species 2016: e.T41672A45231341. http://www.iucnredlist.org/details/41672/0

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

Morrison, A. and Kay, J. 2014. “Short-term Sea Ice Gains Don’t Eliminate Long-term Threats.” Polar Bears International, “Scientists & Explorers Blog” posted 22 September 2014. https://web.archive.org/web/20150509003221/http://www.polarbearsinternational.org/news-room/scientists-and-explorers-blog/short-term-sea-ice-gains-dont-eliminate-long-term-threats

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. 10.1139/AS-2015-0027 http://www.nrcresearchpress.com/doi/abs/10.1139/AS-2015-0027#.VvFtlXpUq50

Overland, J.E. and Wang, M. 2013. When will the summer Arctic be nearly sea ice free? Geophysical Research Letters 40: 2097-2101.

Perovich, D., Meier, W., Tschudi, M.,Farrell, S., Hendricks, S., Gerland, S., Haas, C., Krumpen, T., Polashenski, C., Ricker, R. and Webster, M. 2018. Sea ice. Arctic Report Card 2018, NOAA. https://www.arctic.noaa.gov/Report-Card/Report-Card-2018

Pilfold, N. W., Derocher, A. E., Stirling, I. and Richardson, E. 2015 in press. Multi-temporal factors influence predation for polar bears in a changing climate. Oikos. http://onlinelibrary.wiley.com/doi/10.1111/oik.02000/abstract

Polyak, L., Alley, R.B., Andrews, J.T., Brigham-Grette, J., Cronin, T.M., Darby, D.A., Dyke, A.S., Fitzpatrick, J.J., Funder, S., Holland, M., Jennings, A.E., Miller, G.H., O’Regan, M., Savelle, J., Serreze, M., St. John, K., White, J.W.C. and Wolff, E. 2010. History of sea ice in the Arctic. Quaternary Science Reviews 29:1757-1778.

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

Regehr, E.V., Hostetter, N.J., Wilson, R.R., Rode, K.D., St. Martin, M., Converse, S.J. 2018. Integrated population modeling provides the first empirical estimates of vital rates and abundance for polar bears in the Chukchi Sea. Scientific Reports 8 (1) DOI: 10.1038/s41598-018-34824-7 https://www.nature.com/articles/s41598-018-34824-7

Richardson, E., Stirling, I. and Hik, D.S. 2005. Polar bear (Ursus maritimus) maternity denning habitat in western Hudson Bay: a bottoms-up approach to resource selection functions. Canadian Journal of Zoology 83: 860-870.

Rode, K. and Regehr, E.V. 2010. Polar bear research in the Chukchi and Bering Seas: A synopsis of 2010 field work. Unpublished report to the US Fish and Wildlife Service, Department of the Interior, Anchorage. pdf here.

Rode, K.D., Douglas, D., Durner, G., Derocher, A.E., Thiemann, G.W., and Budge, S. 2013. Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations. Oral presentation by Karyn Rode, 28^th Lowell Wakefield Fisheries Symposium, March 26-29. Anchorage, AK.

Rode, K.D., Regehr, E.V., Douglas, D., Durner, G., Derocher, A.E., Thiemann, G.W., and Budge, S. 2014. Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations. Global Change Biology 20(1):76-88. http://onlinelibrary.wiley.com/doi/10.1111/gcb.12339/abstract

Rode, K. D., R. R. Wilson, D. C. Douglas, V. Muhlenbruch, T.C. Atwood, E. V. Regehr, E.S. Richardson, N.W. Pilfold, A.E. Derocher, G.M Durner, I. Stirling, S.C. Amstrup, M. S. Martin, A.M. Pagano, and K. Simac. 2018. Spring fasting behavior in a marine apex predator provides an index of ecosystem productivity. Global Change Biology http://onlinelibrary.wiley.com/doi/10.1111/gcb.13933/full

Rode, K.D., Wilson, R.R., Regehr, E.V., St. Martin, M., Douglas, D.C. & Olson, J. 2015. Increased land use by Chukchi Sea polar bears in relation to changing sea ice conditions. PLoS One 10 e0142213.

Smith, M. and Rigby, B. 1981. Distribution of polynyas in the Canadian Arctic. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 7-28. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

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

Stirling, I. 1974. Midsummer observations on the behavior of wild polar bears (Ursus maritimus). Canadian Journal of Zoology 52: 1191-1198. http://www.nrcresearchpress.com/doi/abs/10.1139/z74-157#.VR2zaOFmwS4

Stirling, I. 2002. Polar bears and seals in the eastern Beaufort Sea and Amundsen Gulf: a synthesis of population trends and ecological relationships over three decades. Arctic 55 (Suppl. 1):59-76. http://arctic.synergiesprairies.ca/arctic/index.php/arctic/issue/view/42

Stirling, I. and Andriashek, D. 1992. Terrestrial maternity denning of polar bears in the eastern Beaufort Sea area. Arctic 45:363-366.

Stirling, I., Andriashek, D., and Calvert, W. 1993. Habitat preferences of polar bears in the western Canadian Arctic in late winter and spring. Polar Record 29:13-24. http://tinyurl.com/qxt33wj

Stirling, I., Calvert, W., and Andriashek, D. 1984. Polar bear ecology and environmental considerations in the Canadian High Arctic. Pg. 201-222. In Olson, R., Geddes, F. and Hastings, R. (eds.). Northern Ecology and Resource Management. University of Alberta Press, Edmonton.

Stirling, I. and Cleator, H. (eds). 1981. Polynyas in the Canadian Arctic. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Stirling, I, Cleator, H. and Smith, T.G. 1981. Marine mammals. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 45-58. Canadian Wildlife Service Occasional Paper No. 45. Ottawa. Pdf of pertinent excerpts from the Stirling and Cleator volume here.

Stirling, I, Kingsley, M. and Calvert, W. 1982. The distribution and abundance of seals in the eastern Beaufort Sea, 1974–79. Canadian Wildlife Service Occasional Paper 47. Edmonton.

Stirling, I. and Derocher, A.E. 2012. Effects of climate warming on polar bears: a review of the evidence. Global Change Biology 18:2694-2706 http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2012.02753.x/abstract

Stirling, I. and Øritsland, N. A. 1995. Relationships between estimates of ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic. Canadian Journal of Fisheries and Aquatic Sciences 52: 2594 – 2612. http://www.nrcresearchpress.com/doi/abs/10.1139/f95-849#.VNep0y5v_gU

Stroeve, J., Holland, M.M., Meier, W., Scambos, T. and Serreze, M. 2007. Arctic sea ice decline: Faster than forecast. Geophysical Research Letters 34:L09501. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2007GL029703

SWG [Scientific Working Group to the Canada-Greenland Joint Commission on Polar Bear]. 2016. Re-Assessment of the Baffin Bay and Kane Basin Polar Bear Subpopulations: Final Report to the Canada-Greenland Joint Commission on Polar Bear. +636 pp. http://www.gov.nu.ca/documents-publications/349

Walsh, J.E., Fetterer, F., Stewart, J.S. and Chapman, W.L. 2017. A database for depicting Arctic sea ice variations back to 1850. Geographical Review 107(1):89-107. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1931-0846.2016.12195.x

Wang, M. and Overland, J. E. 2012. A sea ice free summer Arctic within 30 years: An update from CMIP5 models. Geophysical Research Letters 39: L18501. doi:10.1029/2012GL052868

Wang, M. and Overland, J.E. 2015. Projected future duration of the sea-ice-free season in the Alaskan Arctic. Progress in Oceanography 136:50-59.

Whiteman, J.P., Harlow, H.J., Durner, G.M., Anderson-Sprecher, R., Albeke, S.E., Regehr, E.V., Amstrup, S.C., and Ben-David, M. 2015. Summer declines in activity and body temperature offer polar bears limited energy savings. Science 349:295-298.

Here are ice conditions at the end of May, which signals the near-end of the critical spring feeding period for polar bears. This is because young-of-the-year seals take to the water to feed themselves, leaving only predator-savvy adults and subadults on the ice from some time in June onward (depending on the region).

Spring is the critical feeding period for polar bears (Crockford 2019, 2020; Lippold et al. 2020; Obbard et al. 2016):

“Unexpectedly, body condition of female polar bears from the Barents Sea has increased after 2005, although sea ice has retreated by ∼50% since the late 1990s in the area, and the length of the ice-free season has increased by over 20 weeks between 1979 and 2013. These changes are also accompanied by winter sea ice retreat that is especially pronounced in the Barents Sea compared to other Arctic areas. Despite the declining sea ice in the Barents Sea, polar bears are likely not lacking food as long as sea ice is present during their peak feeding period. Polar bears feed extensively from April to June when ringed seals have pups and are particularly vulnerable to predation, whereas the predation rate during the rest of the year is likely low.“ [Lippold et al. 2019:988]

NISDC comparative graphs shows 2020 ice extent at 31 May 2020 was higher than 2016 on the same date (and about the same as 2015).

Below is the map for Arctic Canada at 31 May 2020, which has a noteable lack of open water in the Beaufort Sea:

Compare to 31 May 2016:

Last year (31 May 2019), however, was quite different again, especially in Hudson Bay and Hudson Strait:

Stirling et al. (1981:54) discussed why polynyas can be so important in the Southern Beaufort and Hudson Bay (my bold):

“One useful approach is to ask what would happen if the polynya was not there? Obviously this is impossible to evaluate on an experimental basis, but by examining the consequences or natural seasonal variation, some useful insights can be gained. For example, the influence of rapidly changing ice conditions on the availability of open water, and consequently on populations of seals and polar bears, has been observed in the western Arctic. Apparently in response to severe ice conditions in the Beaufort Sea during winter 1973-74, and to a lesser degree in winter 1974-75, numbers of ringed and bearded seals dropped by about 50% and productivity by about 90%. Concomitantly, numbers and productivity of polar bears declined markedly because of the reduction in the abundance of their prey species. …If the shoreleads of the western Arctic or Hudson Bay ceased opening during winter and spring, the effect on marine mammals would be devastating.”

Ice cover over Hudson Bay for the last week of May:

Ice cover over the western Canadian Arctic (Eastern Beaufort Sea) for the last week of May:

The Alaskan portion of the Beaufort was still predominantly multiyear ice at the end of May and thick first year ice in the Chukchi Sea (note this map does not show areas of open water):

Areas of open water in the western Beaufort/Chukchi/Bering Seas at end May 2020:

Ice thickness at this time (less relevant for bears and seal, who prefer first year ice):

See previous posts on spring feeding here and here, with references, and on the Beaufort Sea polynya (recurrent open water) here and here.

References

Crockford, S.J. 2019. The Polar Bear Catastrophe That Never Happened. Global Warming Policy Foundation, London. Available in paperback and ebook formats.

Crockford, S.J. 2020. State of the Polar Bear Report 2019. Global Warming Policy Foundation Report 39, London. PDF here.

Lippold, A., Bourgeon, S., Aars, J., Andersen, M., Polder, A., Lyche, J.L., Bytingsvik, J., Jenssen, B.M., Derocher, A.E., Welker, J.M. and Routti, H. 2019. Temporal trends of persistent organic pollutants in Barents Sea polar bears (Ursus maritimus) in relation to changes in feeding habits and body condition. Environmental Science and Technology 53(2):984-995.

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 http://www.nrcresearchpress.com/doi/abs/10.1139/AS-2015-0027#.VvFtlXpUq50

Stirling, I, Cleator, H. and Smith, T.G. 1981. Marine mammals. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 45-58. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa. Pdf of excerpts of above paper here.

This updated blog post of mine from last year is as pertinent now as it was then: it’s a fully-referenced rebuttal to the misleading ‘facts’ so often presented this time of year to support the notion that polar bears are being harmed due to lack of summer sea ice. Polar Bears International developed ‘Arctic Sea Ice Day’ (15 July) to promote their skewed interpretation of polar bear science at the height of the Arctic melt season. This year I’ve add a ‘Polar Bears and the Arctic Food Chain‘ graphic, which readers are free to download and share. For further information, see “The Polar Bear Catastrophe That Never Happened“.

Summer sea ice loss is finally ramping up: first year is disappearing, as it has done every year since ice came to the Arctic millions of years ago. But critical misconceptions, fallacies, and disinformation abound regarding Arctic sea ice and polar bear survival. Ahead of Arctic Sea Ice Day (15 July), here are 10 fallacies that teachers and parents especially need to know about.

As always, please contact me if you would like to examine any of the references included in this post. These references are what make my efforts different from the activist organization Polar Bears International. PBI virtually never provide references within the content it provides, including material it presents as ‘educational’. Links to previous posts of mine that provide expanded explanations, images, and additional references are also provided.

Sea ice background: extent over the last year

Summer sea ice minimum 2019 (from NSIDC):

Winter sea ice maximum 2020:

Sea ice at 7 July 2019: early summer extent

Despite the fact that 2019 had the 2nd lowest extent for the month of June since 1979, by the end of June 2020 (as was also the case in 2019), there was still ice adjacent to all major polar bear denning areas across the Arctic (see chart below).

In many regions – including Western Hudson Bay, Wrangel Island, and Franz Josef Land – pregnant females that will give birth on land in December come ashore in summer and stay until their newborn cubs are old enough to return with them to the ice the following spring. See Andersen et al. 2012; Ferguson et al. 2000; Garner et al. 1994; Jonkel et al. 1978; Harington 1968; Kochnev 2018; Kolenosky and Prevett 1983; Larsen 1985; Olson et al. 2017; Richardson et al. 2005; Stirling and Andriashek 1992.

Ten fallacies and disinformation about sea ice

1. ‘Sea ice is to the Arctic as soil is to a forest‘. False: this all-or-nothing analogy is a specious comparison. In fact, Arctic sea ice is like a big wetland pond that dries up a bit every summer, where the amount of habitat available to sustain aquatic plants, amphibians and insects is reduced but does not disappear completely. Wetland species are adapted to this habitat: they are able to survive the reduced water availability in the dry season because it happens every year. Similarly, sea ice will always reform in the winter and stay until spring. During the two million or so years that ice has formed in the Arctic, there has always been ice in the winter and spring (even in warmer Interglacials than this one). Moreover, I am not aware of a single modern climate model that predicts winter ice will fail to develop over the next 80 years or so. See Amstrup et al. 2007; Durner et al. 2009; Gibbard et al. 2007; Polak et al. 2010; Stroeve et al. 2007.

2. Polar bears need summer sea ice to survive.  False: polar bears that have fed adequately on young seals in the early spring can live off their fat for five months or more until the fall, whether they spend the summer on land or the Arctic pack ice. Polar bears seldom catch seals in the summer because only predator-savvy adult seals are available and holes in the pack ice allow the seals many opportunities to escape (see the BBC video below). Polar bears and Arctic seals truly require sea ice from late fall through early spring only. See Crockford 2017, 2019; Hammill and Smith 1991:132; Obbard et al. 2016; Pilfold et al. 2016; Stirling 1974; Stirling and Øritsland 1995; Whiteman et al. 2015.

3. Ice algae is the basis for all Arctic life. Only partially true because plankton also thrives in open water during the Arctic summer, which ultimately provides food for the fish species that ringed and bearded seals eat during the summer, which fattens the seals up before the long Arctic winter (as the graphic below shows).

Recent research has shown that less ice in summer has improved ringed and bearded seal health and survival over conditions that existed in the 1980s (when there was a shorter ice-free season and fewer fish to eat): as a consequence, abundant seal populations have been a boon for the polar bears that depend on them for food in early spring. For example, despite living with the most profound decline of summer sea ice in the Arctic polar bears in the Barents Sea around Svalbard are thriving, as are Chukchi Sea polar bears – both contrary to predictions made in 2007 that resulted in polar bears being declared ‘threatened’ with extinction under the Endangered Species Act. See Aars 2018; Aars et al. 2017; Amstrup et al. 2007; Arrigo and van Dijken 2015; Crawford and Quakenbush 2013; Crawford et al. 2015; Crockford 2017, 2019; Frey et al. 2018; Kovacs et al. 2016; Lippold et al. 2019; Lowry 2016; Regehr et al. 2018; Rode and Regehr 2010; Rode et al. 2013, 2014, 2015, 2018.

4. Open water in early spring as well as summer ice melt since 1979 are unnatural and detrimental to polar bear survival. False: melting ice is a normal part of the seasonal changes in the Arctic. In the winter and spring, a number of areas of open water appear because wind and currents rearrange the pack ice – this is not melt, but rather normal polynya formation and expansion. Polynyas and widening shore leads provide a beneficial mix of ice resting platform and nutrient-laden open water that attracts Arctic seals and provides excellent hunting opportunities for polar bears. The map below shows Canadian polynyas and shore leads known in the 1970s: similar patches of open water routinely develop in spring off eastern Greenland and along the Russian coast of the Arctic Ocean. See Dunbar 1981; Grenfell and Maykut 1977; Hare and Montgomery 1949; Smith and Rigby 1981; Stirling and Cleator 1981; Stirling et al. 1981, 1993.

Recurring polynyas and shore leads in Canada known in the 1970s. From Smith and Rigby 1981

5. Climate models do a good job of predicting future polar bear habitat. False: My recent book, The Polar Bear Catastrophe That Never Happened, explains that the almost 50% decline in summer sea ice that was not expected until 2050 actually arrived in 2007, where it has been ever since (yet polar bears are thriving). That is an extraordinarily bad track record of sea ice prediction. Also, contrary to predictions made by climate modelers, first year ice has already replaced much of the multi-year ice in the southern and eastern portion of the Canadian Arctic Archipelago, to the benefit of polar bears. See also ACIA 2005; Crockford 2017, 2019; Durner et al. 2009; Hamilton et al. 2014; Heide-Jorgensen et al. 2012; Perovich et al. 2018; Stern and Laidre 2016; Stroeve et al. 2007; SWG 2016; Wang and Overland 2012.

Simplified predictions vs. observations up to 2007 provided by Stroeve et al. 2007 (courtesy Wikimedia). Sea ice hit an even lower extent in 2012 and all years since then have been below predicted levels.

6. Sea ice is getting thinner and that’s a problem for polar bears.  False: First year ice (less than about 2 metres thick) is the best habit for polar bears because it is also the best habitat for Arctic seals. Very thick multi-year ice that has been replaced by first year ice that melts completely every summer creates more good habitat for seals and bears in the spring, when they need it the most. This has happened especially in the southern and eastern portions of the Canadian Arctic Archipelago (see ice chart below from Sept 2016). Because of such changes in ice thickness, the population of polar bears in Kane Basin (off NW Greenland) has more than doubled since the late 1990s and numbers of bears in M’Clintock Channel (in the SE Archipelago) have reportedly also increased. See Atwood et al. 2016; Durner et al. 2009; Lang et al. 2017; Stirling et al. 1993; SWG 2016.

7. Polar bears in Western and Southern Hudson Bay are most at risk of extinction due to global warming. False: Ice decline in Hudson Bay has been among the lowest across the Arctic. Sea ice decline in Hudson Bay (see graphs below) has been less than one day per year since 1979 compared to more than 4 days per year in the Barents Sea. Hudson Bay ice decline also uniquely happened as a sudden step-change in 1998: there has not been a slow and steady decline. Since 1998, the ice-free season in Western Hudson Bay has been about 3 weeks longer overall than it was in the 1980s but has not become any longer over the last 22 years despite declines in total Arctic sea ice extent or increased carbon dioxide emissions. Ice coverage over Hudson Bay at the end of June in 2020 was as high as last year, providing good sea ice conditions for WH and SH polar bears for the last five years at least. See Castro de la Guardia et al. 2017; Regehr et al. 2016.

Loss of summer sea ice per year, 1979-2014. From Regehr et al. 2016.

8. Breakup of sea ice in Western Hudson Bay now occurs three weeks earlier than it did in the 1980s. False: Breakup now occurs about 2 weeks earlier in summer than it did in the 1980s. The total length of the ice-free season is now about 3 weeks longer (with lots of year-to-year variation). WH polar bears tagged last year were still on the ice at the end of June 2020. See Castro de la Guardia et al. 2017; Cherry et al. 2013; Lunn et al. 2016; and video below, showing the first bear spotted off the ice at Cape Churchill, Western Hudson Bay, on 5 July 2019 – fat and healthy after eating well during the spring:

9. Winter sea ice has been declining since 1979, putting polar bear survival at risk. Only partially true: while sea ice in winter (i.e. March) has been declining gradually since 1979 (see graph below from NOAA), there is no evidence to suggest this has negatively impacted polar bear health or survival, as the decline has been quite minimal. The sea ice chart at the beginning of this post shows that in 2020 there was plenty of ice remaining in March to meet the needs of polar bears and their primary prey (ringed and bearded seals), despite 2019 being the 11th lowest since 1979 (and the highest since 2013).

10. Experts say that with 19 different polar bear subpopulations across the Arctic, there are “19 sea ice scenarios playing out“ (see also here), implying this is what they predicted all along. False: In order to predict the future survival of polar bears, biologists at the US Geological Survey in 2007 grouped polar bear subpopulations with similar sea ice types (which they called ‘polar bear ecoregions,’ see map below). Their predictions of polar bear survival were based on assumptions of how the ice in these four sea ice regions would change over time (with areas in green and purple being similarly extremely vulnerable to effects of climate change). However, it turns out that there is much more variation within and between regions than they expected and more differences in responses to summer sea ice loss than predicted: contrary to predictions, the Barents Sea has had a far greater decline in summer ice extent than any other region, and both Western and Southern Hudson Bay have had relatively little (see #7). See Amstrup et al. 2007; Atwood et al. 2016; Crockford 2017, 2019, 2020; Durner et al. 2009; Lippold et al. 2019; Regehr et al. 2016. My latest book, The Polar Bear Catastrophe That Never Happened, explains why this prediction based on sea ice ecoregions failed so miserably.

References

Aars, J. 2018. Population changes in polar bears: protected, but quickly losing habitat. Fram Forum Newsletter 2018. Fram Centre, Tromso. Download pdf here (32 mb).

Aars, J., Marques,T.A, Lone, K., Anderson, M., Wiig, Ø., Fløystad, I.M.B., Hagen, S.B. and Buckland, S.T. 2017. The number and distribution of polar bears in the western Barents Sea. Polar Research 36:1. 1374125. doi:10.1080/17518369.2017.1374125

ACIA 2005. Arctic Climate Impact Assessment: Scientific Report. Cambridge University Press. See their graphics package of sea ice projections here.

AMAP 2017. [ACIA 2005 update]. Snow, Water, Ice, and Permafrost in the Arctic Summary for Policy Makers (Second Impact Assessment). Arctic Monitoring and Assessment Programme, Oslo. pdf here.

Amstrup, S.C. 2003. Polar bear (Ursus maritimus). In Wild Mammals of North America, G.A. Feldhamer, B.C. Thompson and J.A. Chapman (eds), pg. 587-610. Johns Hopkins University Press, Baltimore.

Amstrup, S.C., Marcot, B.G. & Douglas, D.C. 2007. Forecasting the rangewide status of polar bears at selected times in the 21st century. US Geological Survey. Reston, VA. Pdf here

Andersen, M., Derocher, A.E., Wiig, Ø. and Aars, J. 2012. Polar bear (Ursus maritimus) maternity den distribution in Svalbard, Norway. Polar Biology 35:499-508.

Arrigo, K.R. and van Dijken, G.L. 2015. Continued increases in Arctic Ocean primary production. Progress in Oceanography 136: 60-70. http://dx.doi.org/10.1016/j.pocean.2015.05.002

Atwood, T.C., Marcot, B.G., Douglas, D.C., Amstrup, S.C., Rode, K.D., Durner, G.M. et al. 2016. Forecasting the relative influence of environmental and anthropogenic stressors on polar bears. Ecosphere 7(6): e01370.

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/

Cherry, S.G., Derocher, A.E., Thiemann, G.W., Lunn, N.J. 2013. Migration phenology and seasonal fidelity of an Arctic marine predator in relation to sea ice dynamics. Journal of Animal Ecology 82:912-921. http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12050/abstract

Crawford, J. and Quakenbush, L. 2013. Ringed seals and climate change: early predictions versus recent observations in Alaska. Oral presentation by Justin Crawfort, 28^th Lowell Wakefield Fisheries Symposium, March 26-29. Anchorage, AK. Abstract below, find pdf here:http://seagrant.uaf.edu/conferences/2013/wakefield-arctic-ecosystems/program.php

Crawford, J.A., Quakenbush, L.T. and Citta, J.J. 2015. A comparison of ringed and bearded seal diet, condition and productivity between historical (1975–1984) and recent (2003–2012) periods in the Alaskan Bering and Chukchi seas. Progress in Oceanography 136:133-150.

Crockford, S.J. 2017. Testing the hypothesis that routine sea ice coverage of 3-5 mkm2 results in a greater than 30% decline in population size of polar bears (Ursus maritimus). PeerJ Preprints 19 January 2017. Doi: 10.7287/peerj.preprints.2737v1 Open access. https://peerj.com/preprints/2737/

Crockford, S.J. 2019. The Polar Bear Catastrophe That Never Happened. Global Warming Policy Foundation, London. Available in paperback and ebook formats.

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Derocher, A.E., Wiig, Ø., and Andersen, M. 2002. Diet composition of polar bears in Svalbard and the western Barents Sea. Polar Biology 25 (6): 448-452. http://link.springer.com/article/10.1007/s00300-002-0364-0

Dunbar, M.J. 1981. Physical causes and biological significance of polynyas and other open water in sea ice. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 29-43. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Durner, G.M. and Amstrup, S.C. 1996. Mass and body-dimension relationships of polar bears in northern Alaska. Wildlife Society Bulletin 24(3):480-484.

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Ferguson, S. H., Taylor, M. K., Rosing-Asvid, A., Born, E.W. and Messier, F. 2000. Relationships between denning of polar bears and conditions of sea ice. Journal of Mammalogy 81: 1118-1127.

Frey, K.E., Comiso, J.C., Cooper, L.W., Grebmeier, J.M., and Stock, L.V. 2018. Arctic Ocean primary productivity: the response of marine algae to climate warming and sea ice decline. NOAA Arctic Report Card: Update for 2018.  https://arctic.noaa.gov/Report-Card/Report-Card-2018/ArtMID/7878/ArticleID/778/Arctic-Ocean-Primary-Productivity-The-Response-of-Marine-Algae-to-Climate-Warming-and-Sea-Ice-Decline

Garner, G.W., Belikov, S.E., Stishov, M.S., Barnes, V.G., and Arthur, S.M. 1994. Dispersal patterns of maternal polar bears from the denning concentration on Wrangel Island. International Conference on Bear Research and Management 9(1):401-410.

Gibbard, P. L., Boreham, S., Cohen, K. M. and Moscariello, A. 2005. Global chronostratigraphical correlation table for the last 2.7 million years, modified/updated 2007. Boreas 34(1) unpaginated and University of Cambridge, Cambridge Quaternary http://www.qpg.geog.cam.ac.uk/

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Hamilton, S.G., Castro de la Guardia, L., Derocher, A.E., Sahanatien, V., Tremblay, B. and Huard, D. 2014. Projected polar bear sea ice habitat in the Canadian Arctic Archipelago. PLoS One 9(11):e113746.

Hammill, M.O. and Smith T.G. 1991. The role of predation in the ecology of the ringed seal in Barrow Strait, Northwest Territories, Canada. Marine Mammal Science 7:123–135.

Hare, F.K. and Montgomery, M.R. 1949. Ice, Open Water, and Winter Climate in the Eastern Arctic of North America: Part II. Arctic 2(3):149-164. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3985 Pdf here.

[see also: Hare, F.K. and Montgomery, M.R. 1949. Ice, Open Water, and Winter Climate in the Eastern Arctic of North America: Part I. Arctic 2(2):79-89. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3976 ]

Harington, C. R. 1968. Denning habits of the polar bear (Ursus maritimus Phipps). Canadian Wildlife Service Report Series 5.

Heide-Jorgensen, M.P., Laidre, K.L., Quakenbush, L.T. and Citta, J.J. 2012. The Northwest Passage opens for bowhead whales. Biology Letters 8(2):270-273. doi:10.1098/rsbl.2011.0731

Jonkel, C., Land, E. and Redhead, R. 1978. The productivity of polar bears () in the southeastern Baffin Island area, Northwest Territories. Canadian Wildlife Service Progress Notes 91.

Kochnev, A.A. 2018. Distribution and abundance of polar bear (Ursus maritimus) dens in Chukotka (based on inquiries of representatives of native peoples). Biology Bulletin 45 (8):839-846.

Kolenosky, G.B. and Prevett, J.P. 1983. Productivity and maternity denning of polar bears in Ontario. Bears: Their Biology and Management 5:238-245.

Kovacs, K.M. 2016. Erignathus barbatus. The IUCN Red List of Threatened Species 2016: e.T8010A45225428. http://www.iucnredlist.org/details/full/8010/0

Lang, A., Yang, S. and Kaas, E. 2017. Sea ice thickness and recent Arctic warming Geophysical Research Letters. DOI: 10.1002/2016GL071274

Larsen, T. 1985. Polar bear denning and cub production in Svalbard, Norway. Journal of Wildlife Management 49:320-326.

Lippold, A., Bourgeon, S., Aars, J., Andersen, M., Polder, A., Lyche, J.L., Bytingsvik, J., Jenssen, B.M., Derocher, A.E., Welker, J.M. and Routti, H. 2019. Temporal trends of persistent organic pollutants in Barents Sea polar bears (Ursus maritimus) in relation to changes in feeding habits and body condition. Environmental Science and Technology 53(2):984-995.

Lowry, L. 2016. Pusa hispida. The IUCN Red List of Threatened Species 2016: e.T41672A45231341. http://www.iucnredlist.org/details/41672/0

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

Morrison, A. and Kay, J. 2014. “Short-term Sea Ice Gains Don’t Eliminate Long-term Threats.” Polar Bears International, “Scientists & Explorers Blog” posted 22 September 2014. https://web.archive.org/web/20150509003221/http://www.polarbearsinternational.org/news-room/scientists-and-explorers-blog/short-term-sea-ice-gains-dont-eliminate-long-term-threats

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. 10.1139/AS-2015-0027 http://www.nrcresearchpress.com/doi/abs/10.1139/AS-2015-0027#.VvFtlXpUq50

Overland, J.E. and Wang, M. 2013. When will the summer Arctic be nearly sea ice free? Geophysical Research Letters 40: 2097-2101.

Perovich, D., Meier, W., Tschudi, M.,Farrell, S., Hendricks, S., Gerland, S., Haas, C., Krumpen, T., Polashenski, C., Ricker, R. and Webster, M. 2018. Sea ice. Arctic Report Card 2018, NOAA. https://www.arctic.noaa.gov/Report-Card/Report-Card-2018

Pilfold, N. W., Derocher, A. E., Stirling, I. and Richardson, E. 2015 in press. Multi-temporal factors influence predation for polar bears in a changing climate. Oikos. http://onlinelibrary.wiley.com/doi/10.1111/oik.02000/abstract

Polyak, L., Alley, R.B., Andrews, J.T., Brigham-Grette, J., Cronin, T.M., Darby, D.A., Dyke, A.S., Fitzpatrick, J.J., Funder, S., Holland, M., Jennings, A.E., Miller, G.H., O’Regan, M., Savelle, J., Serreze, M., St. John, K., White, J.W.C. and Wolff, E. 2010. History of sea ice in the Arctic. Quaternary Science Reviews 29:1757-1778.

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

Regehr, E.V., Hostetter, N.J., Wilson, R.R., Rode, K.D., St. Martin, M., Converse, S.J. 2018. Integrated population modeling provides the first empirical estimates of vital rates and abundance for polar bears in the Chukchi Sea. Scientific Reports 8 (1) DOI: 10.1038/s41598-018-34824-7 https://www.nature.com/articles/s41598-018-34824-7

Richardson, E., Stirling, I. and Hik, D.S. 2005. Polar bear (Ursus maritimus) maternity denning habitat in western Hudson Bay: a bottoms-up approach to resource selection functions. Canadian Journal of Zoology 83: 860-870.

Rode, K. and Regehr, E.V. 2010. Polar bear research in the Chukchi and Bering Seas: A synopsis of 2010 field work. Unpublished report to the US Fish and Wildlife Service, Department of the Interior, Anchorage. pdf here.

Rode, K.D., Douglas, D., Durner, G., Derocher, A.E., Thiemann, G.W., and Budge, S. 2013. Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations. Oral presentation by Karyn Rode, 28^th Lowell Wakefield Fisheries Symposium, March 26-29. Anchorage, AK.

Rode, K.D., Regehr, E.V., Douglas, D., Durner, G., Derocher, A.E., Thiemann, G.W., and Budge, S. 2014. Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations. Global Change Biology 20(1):76-88. http://onlinelibrary.wiley.com/doi/10.1111/gcb.12339/abstract

Rode, K. D., R. R. Wilson, D. C. Douglas, V. Muhlenbruch, T.C. Atwood, E. V. Regehr, E.S. Richardson, N.W. Pilfold, A.E. Derocher, G.M Durner, I. Stirling, S.C. Amstrup, M. S. Martin, A.M. Pagano, and K. Simac. 2018. Spring fasting behavior in a marine apex predator provides an index of ecosystem productivity. Global Change Biology http://onlinelibrary.wiley.com/doi/10.1111/gcb.13933/full

Rode, K.D., Wilson, R.R., Regehr, E.V., St. Martin, M., Douglas, D.C. & Olson, J. 2015. Increased land use by Chukchi Sea polar bears in relation to changing sea ice conditions. PLoS One 10 e0142213.

Smith, M. and Rigby, B. 1981. Distribution of polynyas in the Canadian Arctic. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 7-28. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

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

Stirling, I. 1974. Midsummer observations on the behavior of wild polar bears (Ursus maritimus). Canadian Journal of Zoology 52: 1191-1198. http://www.nrcresearchpress.com/doi/abs/10.1139/z74-157#.VR2zaOFmwS4

Stirling, I. 2002. Polar bears and seals in the eastern Beaufort Sea and Amundsen Gulf: a synthesis of population trends and ecological relationships over three decades. Arctic 55 (Suppl. 1):59-76. http://arctic.synergiesprairies.ca/arctic/index.php/arctic/issue/view/42

Stirling, I. and Andriashek, D. 1992. Terrestrial maternity denning of polar bears in the eastern Beaufort Sea area. Arctic 45:363-366.

Stirling, I., Andriashek, D., and Calvert, W. 1993. Habitat preferences of polar bears in the western Canadian Arctic in late winter and spring. Polar Record 29:13-24. http://tinyurl.com/qxt33wj

Stirling, I., Calvert, W., and Andriashek, D. 1984. Polar bear ecology and environmental considerations in the Canadian High Arctic. Pg. 201-222. In Olson, R., Geddes, F. and Hastings, R. (eds.). Northern Ecology and Resource Management. University of Alberta Press, Edmonton.

Stirling, I. and Cleator, H. (eds). 1981. Polynyas in the Canadian Arctic. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Stirling, I, Cleator, H. and Smith, T.G. 1981. Marine mammals. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 45-58. Canadian Wildlife Service Occasional Paper No. 45. Ottawa. Pdf of pertinent excerpts from the Stirling and Cleator volume here.

Stirling, I, Kingsley, M. and Calvert, W. 1982. The distribution and abundance of seals in the eastern Beaufort Sea, 1974–79. Canadian Wildlife Service Occasional Paper 47. Edmonton.

Stirling, I. and Derocher, A.E. 2012. Effects of climate warming on polar bears: a review of the evidence. Global Change Biology 18:2694-2706 http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2012.02753.x/abstract

Stirling, I. and Øritsland, N. A. 1995. Relationships between estimates of ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic. Canadian Journal of Fisheries and Aquatic Sciences 52: 2594 – 2612. http://www.nrcresearchpress.com/doi/abs/10.1139/f95-849#.VNep0y5v_gU

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At the end of March there were two polar bear incidents on the same day in Svalbard, where one bear trashed a holiday cabin. Think a door or a window can keep out a polar bear? Think again!

Here is how the 25 March incident that damaged the cabin pictured above was described (27 March 2021, IcePeople), with a photo of the offending bear:

A polar bear broke into the emergency room of the cabin area at Fredheim on Thursday afternoon, damaging a window and interior furnishings, before it was chased away by a tour group visiting the historic site, according to The Governor of Svalbard.

The break-in, first reported Saturday by Svalbardposten, occurred while two field inspectors living at the station were away.  Karoline Tveråen, a member of the four-member tour group, told the newspaper the bear was easily frightened by the snowmobiles as they approached the cabin.

The governor’s office sent one of its helicopters to the site, but was unable to locate the bear, according to Svalbardposten. The encounter at the cabin about 60 kilometers northeast of Longyearbyen came hours after a bear was seen near several kilometers east of town and was chased into the mountains northeast of town.

The other incident, mentioned in the account above, involved another bear at another location on the same day (see map below for location):

Officials are trying to chase a polar bear visiting Todalen on Thursday morning away from the valley about 10 kilometers southeast of Longyearbyen where numerous cabins are located and spring travellers visit, according to The Governor of Svalbard.

Initial efforts to chase it south were thwarted when the bear returned and approached the landfill at the east end of town, according to a midday update. Attempts are now being made to chase the bear northwest via Hiorthhamn.

“The Governor received a report at 9:15 a.m. today a report that a polar bear has been observed in the vicinity of the cabin area in Todalen,” a statement by the governor’s office notes. “The governor is on its way with a helicopter, snowmobiles and cars. We ask people not to visit the area.”

Svalbardposten reported shortly after noon that snow and poor visibility in the area where complicating efforts to track and chase the bear, but it initially appeared it had ventured away from the cabins. However, it returned and approached the east end of town, resulting in officials from the governor’s office to redirect its push of the animal northwest through Hiorthhamn.

At 3:45 p.m. the governor declared mission accomplished…for the moment.

Ice conditions at the time were typical for recent years: heavy ice on the east side of the archipelago, virtually none on the west coast. Last year was an exception, with significant ice to the south and west in early April. Longyearbyen is fairly easily accessed by bears from the east, over land. Fat ringed and bearded seal pups should be available for polar bears starting in the next few weeks.

Patches of open water in the Arctic that develop in the spring, including polynyas and widening shore leads, are largely due to the actions of wind and currents on mobile pack ice rather than ice melt. Contrary to concerns expressed about possible negative implications of these early patches of open water, these areas have always been critical congregation areas for Arctic seals and are therefore important feeding areas for polar bears in late spring.

Stirling and colleagues discussed decades ago why these areas of open water can be so important in the Southern Beaufort Sea area (Stirling et al. 1981:54):

“One useful approach is to ask what would happen if the polynya was not there? Obviously this is impossible to evaluate on an experimental basis, but by examining the consequences or natural seasonal variation, some useful insights can be gained. For example, the influence of rapidly changing ice conditions on the availability of open water, and consequently on populations of seals and polar bears, has been observed in the western Arctic. Apparently in response to severe ice conditions in the Beaufort Sea during winter 1973-74, and to a lesser degree in winter 1974-75, numbers of ringed and bearded seals dropped by about 50% and productivity by about 90%. Concomitantly, numbers and productivity of polar bears declined markedly because of the reduction in the abundance of their prey species. …If the shoreleads of the western Arctic or Hudson Bay ceased opening during winter and spring, the effect on marine mammals would be devastating.” [my bold]

Dunbar (1981:32) had this to say about Hudson Bay’s persistent flaw leads:

“The largest flaw leads normally found in Canada are in Hudson Bay. The Hudson Bay lead, seaward of the fast ice, is so wide as to have generated the belief that the whole of the bay, except for the fast ice region along the shore, stayed unfrozen all winter…In the Hudson Bay instance, the myth of an open bay all winter was dispelled by Hare and Montgomery (1949), who showed that the pattern of of air temperatures over the whole region made an open Hudson Bay in winter very improbable. By overflying the area, they demonstrated that in fact the central bay is covered with ice in winter, although there normally exists a large flaw lead seaward of the fast ice on both sides of the bay and extending into northern James Bay. This flaw lead varies in width according to the direction of the wind from “about a mile and a half to 30 or 40 nautical miles” (Hare and Montgomery 1949).” [my bold]

More than 60 years ago, Hare and Montgomery (1949:160, 163) described the formation of a wide shore lead that formed in eastern Hudson Bay in early May 1948:

“The shore lead, which seems to have caused so much confusion in estimating the ice cover of Hudson Bay, may at times be entirely absent. Along the east coast from Great Whale River to Port Harrison the “Ice” reconnaissance of 8 March 1949 found no suggestion of open water. There were traces of old refrozen leads but none of them as large or as continuous as the one found along this same coast by the “Cariberg” reconnaissance of 6 May 1948. At that time the lane of open water off Port Harrison [now called Inukjuak, on the east coast] was 25 to 30 miles wide and seemed to stretch north and south along the coast as far as could be seen. It should be noted that this wide shore lead resulted after several days of NE winds which had effectively driven the ice offshore.” [my bold]

See previous posts here, here, and here.

Canadian Arctic Daily Sea ice at 21 May 2021 (and years previously to 2013)

References

Dunbar, M.J. 1981. Physical causes and biological significance of polynyas and other open water in sea ice. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 29-43. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Hare, F.K. and Montgomery, M.R. 1949. Ice, Open Water, and Winter Climate in the Eastern Arctic of North America: Part II. Arctic 2(3):149-164. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3985 Pdf here.

[see also: Hare, F.K. and Montgomery, M.R. 1949. Ice, Open Water, and Winter Climate in the Eastern Arctic of North America: Part I. Arctic 2(2):79-89. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3976 ]

Stirling, I. and Cleator, H. (eds). 1981. Polynyas in the Canadian Arctic. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Smith, M. and Rigby, B. 1981. Distribution of polynyas in the Canadian Arctic. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 7-28. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Stirling, I, Cleator, H. and Smith, T.G. 1981. Marine mammals. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 45-58. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa. Pdf of pertinent excerpts of above papers here.

Two recent incidents really remind me of the opening scene in my polar bear attack thriller, EATEN, and this time both were captured on film. They involved bears in good physical condition and luckily, no one has been hurt. There is still sea ice off the Northern Peninsula, which has brought the bears from the north.

On Sunday (10 April) in St. Anthony, a woman was alerted by her dog to what she though was someone on the front porch and found herself literally face to face with a polar bear when she opened the door; it then hopped up on her roof. The next day, in Goose Cove, a woman watched two bears (probably a female with a two year old male cub) explore the outside of a neighbour’s house and then walk across her driveway.

Here are the details of Sunday’s incident in St. Anthony (VOCM, 12 April 2022):

A St. Anthony woman says she’s glad she didn’t know just how close a polar bear got to paying an unwelcome visit to her home until after the bear was long gone.

Danny Keats captured his neighbour Bobbie Stevens’ close encounter on surveillance video and his son Kenneth has been sharing it on social media.

Bobbie says she was on the couch when her dog alerted her to something going on out by the door. She went to the door thinking there was someone there, and when she opened the door to look out, she was staring in the face of a polar bear, “and the polar bear was beautiful” she laughs. Fortunately, she didn’t take too long to take the scene in, closed the door and called 911.

Bobbie says it wasn’t until she saw the surveillance video showing the bear climbing onto her roof, that she got scared.

Watch the short surveillance videos to see how close she got to the bear when she opened the door:

https://www.facebook.com/kenneth.keats.5/posts/10166433900150346

The Goose Cove incident happened on Monday and was reported in detail by the CBC (11 April 2022). Goose Cove is just south of St. Anthony along the east coast of the Northern Peninsula:

Agnes McCarthy of Goose Cove, also on the Northern Peninsula, got a close look at two polar bears as they took a walk through her driveway — one of them checking out a neighbour’s house and then returning.

Sea ice conditions

And further up the coast, in Labrador:

Big picture sea ice conditions, across Canada:

At the end of March there were two polar bear incidents on the same day in Svalbard, where one bear trashed a holiday cabin. Think a door or a window can keep out a polar bear? Think again!

Here is how the 25 March incident that damaged the cabin pictured above was described (27 March 2021, IcePeople), with a photo of the offending bear:

A polar bear broke into the emergency room of the cabin area at Fredheim on Thursday afternoon, damaging a window and interior furnishings, before it was chased away by a tour group visiting the historic site, according to The Governor of Svalbard.

The break-in, first reported Saturday by Svalbardposten, occurred while two field inspectors living at the station were away.  Karoline Tveråen, a member of the four-member tour group, told the newspaper the bear was easily frightened by the snowmobiles as they approached the cabin.

The governor’s office sent one of its helicopters to the site, but was unable to locate the bear, according to Svalbardposten. The encounter at the cabin about 60 kilometers northeast of Longyearbyen came hours after a bear was seen near several kilometers east of town and was chased into the mountains northeast of town.

The other incident, mentioned in the account above, involved another bear at another location on the same day (see map below for location):

Officials are trying to chase a polar bear visiting Todalen on Thursday morning away from the valley about 10 kilometers southeast of Longyearbyen where numerous cabins are located and spring travellers visit, according to The Governor of Svalbard.

Initial efforts to chase it south were thwarted when the bear returned and approached the landfill at the east end of town, according to a midday update. Attempts are now being made to chase the bear northwest via Hiorthhamn.

“The Governor received a report at 9:15 a.m. today a report that a polar bear has been observed in the vicinity of the cabin area in Todalen,” a statement by the governor’s office notes. “The governor is on its way with a helicopter, snowmobiles and cars. We ask people not to visit the area.”

Svalbardposten reported shortly after noon that snow and poor visibility in the area where complicating efforts to track and chase the bear, but it initially appeared it had ventured away from the cabins. However, it returned and approached the east end of town, resulting in officials from the governor’s office to redirect its push of the animal northwest through Hiorthhamn.

At 3:45 p.m. the governor declared mission accomplished…for the moment.

Ice conditions at the time were typical for recent years: heavy ice on the east side of the archipelago, virtually none on the west coast. Last year was an exception, with significant ice to the south and west in early April. Longyearbyen is fairly easily accessed by bears from the east, over land. Fat ringed and bearded seal pups should be available for polar bears starting in the next few weeks.

Patches of open water in the Arctic that develop in the spring, including polynyas and widening shore leads, are largely due to the actions of wind and currents on mobile pack ice rather than ice melt. Contrary to concerns expressed about possible negative implications of these early patches of open water, these areas have always been critical congregation areas for Arctic seals and are therefore important feeding areas for polar bears in late spring.

Stirling and colleagues discussed decades ago why these areas of open water can be so important in the Southern Beaufort Sea area (Stirling et al. 1981:54):

“One useful approach is to ask what would happen if the polynya was not there? Obviously this is impossible to evaluate on an experimental basis, but by examining the consequences or natural seasonal variation, some useful insights can be gained. For example, the influence of rapidly changing ice conditions on the availability of open water, and consequently on populations of seals and polar bears, has been observed in the western Arctic. Apparently in response to severe ice conditions in the Beaufort Sea during winter 1973-74, and to a lesser degree in winter 1974-75, numbers of ringed and bearded seals dropped by about 50% and productivity by about 90%. Concomitantly, numbers and productivity of polar bears declined markedly because of the reduction in the abundance of their prey species. …If the shoreleads of the western Arctic or Hudson Bay ceased opening during winter and spring, the effect on marine mammals would be devastating.” [my bold]

Dunbar (1981:32) had this to say about Hudson Bay’s persistent flaw leads:

“The largest flaw leads normally found in Canada are in Hudson Bay. The Hudson Bay lead, seaward of the fast ice, is so wide as to have generated the belief that the whole of the bay, except for the fast ice region along the shore, stayed unfrozen all winter…In the Hudson Bay instance, the myth of an open bay all winter was dispelled by Hare and Montgomery (1949), who showed that the pattern of of air temperatures over the whole region made an open Hudson Bay in winter very improbable. By overflying the area, they demonstrated that in fact the central bay is covered with ice in winter, although there normally exists a large flaw lead seaward of the fast ice on both sides of the bay and extending into northern James Bay. This flaw lead varies in width according to the direction of the wind from “about a mile and a half to 30 or 40 nautical miles” (Hare and Montgomery 1949).” [my bold]

More than 60 years ago, Hare and Montgomery (1949:160, 163) described the formation of a wide shore lead that formed in eastern Hudson Bay in early May 1948:

“The shore lead, which seems to have caused so much confusion in estimating the ice cover of Hudson Bay, may at times be entirely absent. Along the east coast from Great Whale River to Port Harrison the “Ice” reconnaissance of 8 March 1949 found no suggestion of open water. There were traces of old refrozen leads but none of them as large or as continuous as the one found along this same coast by the “Cariberg” reconnaissance of 6 May 1948. At that time the lane of open water off Port Harrison [now called Inukjuak, on the east coast] was 25 to 30 miles wide and seemed to stretch north and south along the coast as far as could be seen. It should be noted that this wide shore lead resulted after several days of NE winds which had effectively driven the ice offshore.” [my bold]

See previous posts here, here, and here.

Canadian Arctic Daily Sea ice at 21 May 2021 (and years previously to 2013)

References

Dunbar, M.J. 1981. Physical causes and biological significance of polynyas and other open water in sea ice. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 29-43. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Hare, F.K. and Montgomery, M.R. 1949. Ice, Open Water, and Winter Climate in the Eastern Arctic of North America: Part II. Arctic 2(3):149-164. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3985 Pdf here.

[see also: Hare, F.K. and Montgomery, M.R. 1949. Ice, Open Water, and Winter Climate in the Eastern Arctic of North America: Part I. Arctic 2(2):79-89. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3976 ]

Stirling, I. and Cleator, H. (eds). 1981. Polynyas in the Canadian Arctic. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Smith, M. and Rigby, B. 1981. Distribution of polynyas in the Canadian Arctic. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 7-28. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Stirling, I, Cleator, H. and Smith, T.G. 1981. Marine mammals. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 45-58. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa. Pdf of pertinent excerpts of above papers here.

Two recent incidents really remind me of the opening scene in my polar bear attack thriller, EATEN, and this time both were captured on film. They involved bears in good physical condition and luckily, no one has been hurt. There is still sea ice off the Northern Peninsula, which has brought the bears from the north.

On Sunday (10 April) in St. Anthony, a woman was alerted by her dog to what she though was someone on the front porch and found herself literally face to face with a polar bear when she opened the door; it then hopped up on her roof. The next day, in Goose Cove, a woman watched two bears (probably a female with a two year old male cub) explore the outside of a neighbour’s house and then walk across her driveway.

Here are the details of Sunday’s incident in St. Anthony (VOCM, 12 April 2022):

A St. Anthony woman says she’s glad she didn’t know just how close a polar bear got to paying an unwelcome visit to her home until after the bear was long gone.

Danny Keats captured his neighbour Bobbie Stevens’ close encounter on surveillance video and his son Kenneth has been sharing it on social media.

Bobbie says she was on the couch when her dog alerted her to something going on out by the door. She went to the door thinking there was someone there, and when she opened the door to look out, she was staring in the face of a polar bear, “and the polar bear was beautiful” she laughs. Fortunately, she didn’t take too long to take the scene in, closed the door and called 911.

Bobbie says it wasn’t until she saw the surveillance video showing the bear climbing onto her roof, that she got scared.

Watch the short surveillance videos to see how close she got to the bear when she opened the door:

https://www.facebook.com/kenneth.keats.5/posts/10166433900150346

The Goose Cove incident happened on Monday and was reported in detail by the CBC (11 April 2022). Goose Cove is just south of St. Anthony along the east coast of the Northern Peninsula:

Agnes McCarthy of Goose Cove, also on the Northern Peninsula, got a close look at two polar bears as they took a walk through her driveway — one of them checking out a neighbour’s house and then returning.

Sea ice conditions

And further up the coast, in Labrador:

Big picture sea ice conditions, across Canada:

Arctic sea ice is beginning to melt and the end of spring is drawing near. Mating season is over for polar bears as is the gorging on young seals in most regions as weaned pups head into open water to feed for themselves. Only predator-savvy adult and subadult seals remain on the ice while they moult a new hair coat, so successful hunts by most polar bears will become more and more uncommon (e.g. Obbard et al. 2016).

Arctic sea ice overall

Sea ice thickness

Where red bits are 5m thick and even the green/yellow is 2.5-3.5m. This thick ice is not likely to melt over the summer but it can get broken up and flushed out of the Arctic by winds and currents, where it will melt in warmer waters.

The graph below shows that sea ice extent for May 2023, according to NSIDC compared to previous years, is only slightly less than it was in 1989 and 1995:

Sea ice Canada

Open water leads and polynyas in the sea ice, which are clearly visible in the ice chart below, are now important areas for polar bears to attempt to hunt, because these highly productive areas attract seals (Stirling et al. 1981).

Barents and Kara Seas, East Greenland

Svalbard subregion

Ice extent around Svalbard is declining, as it does every year about this time:

However, there is still abundant ice in the eastern and northern regions around Svalbard for polar bears to continue hunting attempts:

References

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. 10.1139/AS-2015-0027 http://www.nrcresearchpress.com/doi/abs/10.1139/AS-2015-0027#.VvFtlXpUq50

Stirling, I, Cleator, H. and Smith, T.G. 1981. Marine mammals. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 45-58. Canadian Wildlife Service Occasional Paper No. 45. Ottawa. Pdf of pertinent excerpts from the Stirling and Cleator volume here.