This updated blog post of minefrom last yearis as pertinent now as it was then: it’s a fully-referenced rebuttal to themisleading ‘facts’so often presented this time of year to support the notion thatpolar bears are being harmeddue to lack ofsummer 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 ofArctic 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 organizationPolar 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.
In many regions – includingWestern Hudson Bay,Wrangel Island, andFranz 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 aspecious 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 predictswinterice 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.
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 hasimproved ringed and bearded seal health and survivalover 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 Arcticpolar bears in the Barents Sea around Svalbard are thriving, as areChukchi 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 1979are 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 normalpolynyaformation and expansion.Polynyas and widening shore leadsprovide a beneficial mix of ice resting platform andnutrient-laden open waterthat 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 theRussian 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.
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 icein 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.
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 the11th lowestsince 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.
Aars, J. 2018.Population changes in polar bears: protected, but quickly losing habitat.Fram Forum Newsletter 2018. Fram Centre, Tromso. Download pdfhere(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 Research36:1. 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 projectionshere.
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. pdfhere.
Amstrup, S.C. 2003. Polar bear (Ursus maritimus). InWild 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. Pdfhere
Andersen, M., Derocher, A.E., Wiig, Ø. and Aars, J. 2012.Polar bear (Ursus maritimus) maternity den distribution in Svalbard, Norway.Polar Biology35:499-508.
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.Ecosphere7(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 Series564:225–233.http://www.int-res.com/abstracts/meps/v564/p225-233/
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 Oceanography136:133-150.
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 Preprints19 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 inpaperbackandebookformats.
Crockford, S.J. 2020.State of the Polar Bear Report 2019. Global Warming Policy Foundation Report 39, London. pdfhere.
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 Bulletin24(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 Monographs79: 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 Mammalogy81: 1118-1127.
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 Management9(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.Boreas34(1) unpaginated and University of Cambridge, Cambridge Quaternaryhttp://www.qpg.geog.cam.ac.uk/
Lang, A., Yang, S. and Kaas, E. 2017.Sea ice thickness and recent Arctic warmingGeophysical Research Letters. DOI: 10.1002/2016GL071274
Larsen, T. 1985.Polar bear denning and cub production in Svalbard, Norway.Journal of Wildlife Management49:320-326.
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.
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 Applications26(5):1302-1320.DOI: 10.1890/15-1256
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-2015-0027http://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 Letters40: 2097-2101.
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 Reviews29:1757-1778.
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 Letters12: 20160556.http://rsbl.royalsocietypublishing.org/content/12/12/20160556Supplementary datahere.
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 Reports8 (1) DOI: 10.1038/s41598-018-34824-7https://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 Zoology83: 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 reportto the US Fish and Wildlife Service, Department of the Interior, Anchorage. pdfhere.
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, 28thLowell 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 Biology20(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 Biologyhttp://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 One10 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.Cryosphere10: 2027-2041.
Stirling, I. and Andriashek, D. 1992.Terrestrial maternity denning of polar bears in the eastern Beaufort Sea area.Arctic45:363-366.
Stirling, I., Andriashek, D., and Calvert, W. 1993.Habitat preferences of polar bears in the western Canadian Arctic in late winter and spring.Polar Record29:13-24.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 PaperNo. 45. Ottawa.Pdf of pertinent excerpts from the Stirling and Cleator volumehere.
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 Paper47. Edmonton.
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
Wang, M. and Overland, J. E. 2012.A sea ice free summer Arctic within 30 years: An update from CMIP5 models.Geophysical Research Letters39: 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 Oceanography136:50-59.
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.Science349:295-298.