Grim predictions of the imminent demise of polar bears – their “harsh prophetic reality” as it’s been called – have been touted since at least 2001. But such depressing prophesies have so widely missed the mark they can now be said to have failed.
While polar bears may be negatively affected by declines in sea ice sometime in the future, so far there is no convincing evidence that any unnatural harm has come to them. Indeed, global population size (described by officials as a “tentative guess“) appears to have grown slightly over this time, as the maximum estimated number was 28,370 in 1993 (Wiig and colleagues 1995; range 21,470-28,370) but rose to 31,000 in 2015 (Wiig and colleagues 2015, [pdf here] aka 2015 IUCN Red List assessment; range 22,000-31,000).
These ominous prophesies have been promoted primarily by Ian Stirling, Steven Amstrup, Andrew Derocher and a few other IUCN Polar Bear Specialist Group (PBSG) members but ironically, it’s data collected by their colleagues that’s refuted their message of doom.
Here are the predictions (in no particular order, references at the end):
Prediction 1. Western Hudson Bay (WHB) polar bear numbers will continue to decline beyond 2004 due to ever-earlier breakup and ever-later freeze-up of sea ice.
FAIL – An aerial survey conducted by Seth Stapleton and colleagues (2014) in 2011 produced an estimate of about 1030 bears and their report stated:
“This figure is similar to a 2004 mark–recapture estimate but higher than projections indicating declining abundance since then.”
This 1030 figure is the one being used by the IUCN PBSG and Environment Canada for WHB, as a limited mark-recapture study conducted the same year (Lunn and colleagues 2014) did not survey the entire WHB region and therefore not comparable to the 2004 count.
Prediction 2. Breakup of sea ice in Western Hudson Bay (WHB) will come progressively earlier and freeze-up dates progressively later (after 1999), as CO2 levels from burning fossil fuel increase global temperatures.
FAIL – Researchers Nick Lunn and colleagues (2014) determined that there has been no trend in breakup or freeze-up dates between 2001 and 2010. While no analyses of breakup or freeze-up dates for WHB since 2010 have been published, this pattern seems to have continued to at least 2015.
Prediction 3. Chukchi Sea polar bears will be the most harmed by summer sea ice declines because they experience some of the largest sea ice losses of any subpopulation (and thus, the longest open-water season each year).
FAIL – A recent study of Chukchi bears (2008-2011) found them in better condition than they were in the 1980s when summer open-water seasons were short – indeed, only Foxe Basin bears were fatter than Chukchi bears. They were also reproducing well (Rode et al. 2010, 2013, 2014), with some females raising litters of triplets (see lead photo), a rare sight outside Western Hudson Bay.
Prediction 4. Cannibalism will increase as summer sea ice extent declines worsen.
FAIL – Cannibalism is a natural phenomenon in polar bears and none of the few incidents reported recently have involved obviously thin or starving polar bears (even the most recent example, filmed in mid-August 2015 in Baffin Bay when sea ice levels in the region were high), despite the fact that 2012 recorded the lowest summer ice extent since 1979. Incidents of cannibalism cannot be said to be increasing because there is no scientific baseline to which recent occurrences can be compared.
Prediction 5. Drowning deaths of polar bears will increase as summer sea ice continues to decline (driven home by a high-profile incident in 2004).
FAIL – There have been no further confirmed reports of polar bear drowning deaths associated with extensive open water swimming since that contentious 2004 event, even though the two lowest extents of summer sea ice have occurred since then (2007 and 2012). A more rigorous study of swimming prowess found polar bears, including cubs, are capable of successfully making long-distance swims. Indeed, challenging open-water swims don’t happen only in summer: in late March 2015, a polar bear swam through open water from the pack ice off Newfoundland to the Hibernia oil platform well offshore.
Prediction 6. There will be more and more problems onshore in summer with starving polar bears because of reduced sea ice.
FAIL – There have been more problem bears in summer over the last few years in Western Hudson Bay as well as other regions but few of those bears were shown to be thin or starving. A well-publicized attack occurred in Churchill in the fall of 2013 but was not associated with an especially early break-up of sea ice nor a late freeze-up. Incidents last summer in the Kara Sea (Russia) involved bears in good condition. Polar bears are potentially dangerous no matter what their condition but death by starvation of young or old bears (or injured ones) are natural events that occur often, not evidence of declining sea ice.
Prediction 7. Southern Beaufort Sea polar bears can be used to predict how bears living in the Chukchi Sea and the Barents Sea are doing because they are similar ‘sea ice ecoregions’, says the Circumpolar Action Plan for future research proposed by Dag Vongraven and colleagues in 2012.
FAIL – Recent research has shown that Chukchi Sea bears actually fared better with the long open-water seasons of the late 2000s than in the short seasons of the 1980s. In contrast, Southern Beaufort Sea bears have suffered profoundly from periodic episodes of thick spring ice (every 10 years or so since the 1960s), a phenomenon that is unique to that region. In fact, sea ice conditions for Chukchi Sea and Southern Beaufort bears could hardly be more different. With Southern Beaufort bears the more vulnerable to decline from natural variations in sea ice, the plan to treat these two regions as equivalent is a farce and totally undermines the Circumpolar Action Plan proposed by the IUCN PBSG.
Prediction 8. Western Hudson Bay (WHB) polar bears can be used to predict how bears living in Foxe Basin, and Davis Strait are doing because these are all similar ‘sea ice ecoregions’, says the Circumpolar Action Plan for future research proposed by Dag Vongraven and colleagues in 2012.
FAIL – WHB bears not only have variable breakup and freeze-up dates to contend with but also face occasional years with thick spring ice and springs with either very thick or very thin snow cover that strongly affects the availability of their ringed seal prey. Davis Strait bears, on the other hand, face some variability in sea ice conditions but have access to a super-abundant supply of harp seal prey in spring. With WHB polar bears by far the more vulnerable to decline from natural variations in sea ice and prey availability than Davis Strait bears, the plan to treat these two regions as equivalent is a farce and totally undermines the proposed Circumpolar Action Plan.
Prediction 9. Continued late formation of fall sea ice off Svalbard in the Barents Sea will devastate polar bears that traditionally den in this region.
FAIL – Preliminary results from the latest population count of Svalbard area polar bears showed a 42% increase over the estimate for 2004, despite very late ice formation in the fall of 2013 around maternity denning areas. Other research has shown that bears move back and forth readily between Svalbard, Norway and Franz Josef Land, Russia (which so far has always had sea ice by late fall). This means that Svalbard bears have been able to adapt easily to recent low ice conditions.
FAIL – Sea ice at September has been variable since 2007 but there has been no declining trend, a pattern sea ice experts admit may continue for 10 years or more beyond 2014 even if declining sea ice predictions are true (Swart and colleagues, 2015). In other words, CO2 levels have not been the control knob for polar bear health.
Polar bears are not fragile canaries in an Arctic climate-change coal mine but resilient and adaptable predators remarkably suited to their highly variable habitat.
Here’s a summary of what the 2015 Red List assessment (Wiig et al. 2015) said:
The previous status of ‘Vulnerable’ was upheld but no projections were made beyond 2050. They said there is only a 70% chance that numbers will decline by 30% over the next 35 years, which is only slightly higher than a 50:50. It also means there is a 30% chance that the numbers WILL NOT decline by 30% over the next 35 years.It stated explicitly that the risk of a population decline of 80% or greater by 2050 is virtually zero (pg. 16).
In other words, the status of ‘Vulnerable’ is based only on a possible decline in population numbers, despite their current high numbers, and there is no imminent risk of extinction. The current population trend is stated as UNKNOWN.
[Don’t miss this follow-up post: Biggest threat to polar bears reconsidered (27 February 2016, International Polar Bear Day post]
References for the Predictions
Amstrup, S.C. 2011. Polar bears and climate change: certainties, uncertainties, and hope in a warming world. In: R.T.Watson, T.J. Cade, M. Fuller, G. Hunt and E. Potapov (eds.), Gyrfalcons and Ptarmigan in a Changing World, Volume 1. The Peregrine Fund, Boise, Idaho.
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.
Amstrup, S.C.,Marcot, B.G. and Douglas, D.C. 2008. A Bayesian network modeling approach to forecasting the 21st century worldwide status of polar bears. Pp. 213–268 in Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications, E.T. DeWeaver, C.M. Bitz and L.B. Tremblay (eds.). Geophysical Monograph 180. American Geophysical Union, Washington, D.C.
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.
Atwood, T.C., Marcot, B.G., Douglas,D.C., Amstrup, S.C., Rode, K.D., Durner, G.M. and Bromaghin, J.F. 2014. Evaluating and ranking threats to the long-term persistence of polar bears. USGS Open-File Report 2014–1254.
Derocher, A.E., Aars, J., Steven C. Amstrup, S.C. and nine others. 2013. Rapid ecosystem change and polar bear conservation. Conservation Letters 6(5):368-375.
Derocher, A.E., Lunn, N.J. and Stirling, I. 2004. Polar bears in a warming climate. Integrative and Comparative Biology 44: 163–176.
Durner, G.M., Douglas, D.C., Nielson, R.M., Amstrup, S.C., McDonald, T.L. and 12 others. 2007. Predicting 21st-century polar bear habitat distribution from global climate models. Administrative Report, US Geological Survey. Reston, Virginia.
Durner, G.M., Douglas, D.C., Nielson, R.M., Amstrup, S.C., McDonald, T.L. and 12 others. 2009. Predicting 21st-century polar bear habitat distribution from global climate models. Ecological Monographs 79: 25–58.
Hassol, S.J. 2004. Impacts of a Warming Arctic : Arctic Climate Impact Assessment. Cambridge University Press, Cambridge UK.
Obbard, M.E., Theimann, G.W., Peacock, E. and DeBryn, T.D. (eds) 2010. Polar Bears: Proceedings of the 15th meeting of the Polar Bear Specialists Group IUCN/SSC, 29June-3 July, 2009, Copenhagen,Denmark. Gland, Switzerland and Cambridge UK, IUCN. http://pbsg.npolar.no/en/meetings/
Overland, J.E. andWang, M. 2013. When will the summer Arctic be nearly sea ice-free? Geophysical Research Letters 40: 2097–2101.
Stirling, I. and Derocher, A.E. 2012. Effects of climate warming on polar bears: a review of the evidence. Global Change Biology 18(9): 2694–2706.
Stirling, I. and Parkinson, C.L. 2006. Possible effects of climate warming on selected populations of polar bears (Ursus maritimus ) in the Canadian Arctic. Arctic 59: 261–275.
Vongraven,D., Aars, J., Amstrup, S., et al. 2012. A circumpolar monitoring framework for polar bears. Ursus 23 (sp2): 1–66. pdf here.
Wang M., Overland, J.E., Stabeno, P. 2012. Future climate of the Bering and Chukchi Seas projected by global climate models. Deep-Sea Research Part II: Topical Studies in Oceanography 65–70: 46–57.
References for the Evidence that the above Predictions have Failed
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.
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.
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.
Crockford, S.J. 2015. “The Arctic Fallacy: sea ice stability and the polar bear.” GWPF Briefing 16. The Global Warming Policy Foundation, London. Pdf here.
Derocher, A.E. and Stirling, I. 1996. Aspects of survival in juvenile polar bears. Canadian Journal of Zoology 73: 1246–1252.
Derocher, A.E., Stirling, I. and Andriashek, D. 1992. Pregnancy rates and progesterone levels of polar bears in western Hudson Bay. Canadian Journal of Zoology 70: 561–566.
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.
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.
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(4): 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’swestern Arctic: harvest-based monitoring 1992–2011. Arctic 65: 377–390.
Lunn, N.J., Servanty, S., Regehr, E.V., Converse, S.J., Richardson, E. and Stirling, I. 2014. Demography and population assessment of polar bears in Western Hudson Bay, Canada. Environment Canada Research Report. July 2014. PDF HERE
Peacock, E., Derocher, A.E., Lunn, N.J. and Obbard, M.E. 2010. Polar bear ecology and management in Hudson Bay in the face of climate change. In: A Little Less Arctic: Top Predators in the World’s Largest Northern Inland Sea, Hudson Bay. S.H. Ferguson, L.L. Loseto and M.L. Mallory (eds). Springer.
Peacock, E., Taylor, M.K., Laake, J. and Stirling, I. 2013. Population ecology of polar bears in Davis Strait, Canada and Greenland. Journal of Wildlife Management 77: 463–476.
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. doi: 10.1111/oik.02000
Pagano, A.M., Durner, G.M., Amstrup, S.C., Simac, K.S. and York, G.S. 2012. Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water. Canadian Journal of Zoology 90: 663-676.
Rode, K.D., Peacock, E., Taylor, M., Stirling, I., Born, E.W., Laidre, K.L. and Wiig, Ø. 2012. A tale of two polar bear populations: ice habitat, harvest and body condition. Population Ecology 54: 3–18. [Davis Strait and Baffin Bay]
Rode, K.D., Douglas, D., Durner, G., Derocher, A.E., Thiemann, G.W. and Budge, S. 2013. Comparison in polar bear response to sea ice loss in the Chukchi and southern Beaufort Seas. Oral presentation at the 28th Lowell Wakefield Fisheries Symposium, March 26–29. Anchorage, AK.
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., 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.
Schliebe, S., Rode, K.D., Gleason, J.S., Wilder, J., Proffitt, K., Evans, T.J., and S. Miller. 2008. Effects of sea ice extent and food availability on spatial and temporal distribution of polar bears during the fall open-water period in the southern Beaufort Sea. Polar Biology 31:999-1010.
Stapleton S., Atkinson, S., Hedman, D., and Garshelis, D. 2014. Revisiting Western Hudson Bay: using aerial surveys to update polar bear abundance in a sentinel population. Biological Conservation 170:38-47. http://www.sciencedirect.com/science/article/pii/S0006320713004618#
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. 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). Blackwell Science.
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., Pearson, A.M. and Bunnell, F.L. 1976. Population ecology studies of polar and grizzly bears in northern Canada. Transactions of the 41st North American Wildlife Conference 41: 421–430.
Stirling, I., Schweinsburg, R.E., Kolenasky, G.B., Juniper, I., Robertson, R.J. and Luttich, S. 1980. Proceedings of the 7th meeting of the Polar Bear Specialists Group IUCN/SSC, 30 January-1 February, 1979, Copenhagen, Denmark. Gland, Switzerland and Cambridge UK, IUCN, pp. 45–53.
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., Lunn, N.J., Iacozza, J., Elliott, C. and Obbard, M. 2004. Polar bear distribution and abundance on the southwestern Hudson Bay coast during open water season, in relation to population trends and annual ice patterns. Arctic 57: 15–26.
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.
Swart, N.C., Fyfe, J.C., Hawkins, E., Kay, J.E. and Jahn, A. 2015. Influence of internal variability on Arctic sea-ice trends. Nature Climate Change 5(2): 86–89.
Wiig, Ø., Born, E.W., and Garner, G.W. (eds.) 1995. 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. http://pbsg.npolar.no/en/meetings/
Wiig, Ø., Amstrup, S., Atwood, T., Laidre, K., Lunn, N., Obbard, M., Regehr, E. & Thiemann, G. 2015. Ursus maritimus. The IUCN Red List of Threatened Species 2015: e.T22823A14871490. http://www.iucnredlist.org/details/22823/0