Despite more CO2 in the atmosphere (424 vs. 392, for June), there was more sea ice cover in the Barents Sea at mid-July this year than there was in 2012.
This region has seen about 6 times the amount of summer sea ice loss as any other region of the Arctic (Regehr et al. 2016): Barents Sea bears now have a longer ice-free season than the famous Western Hudson Bay bears that we hear so much about.
Yet contrary to predictions, which insisted that protracted poor ice conditions in summer would inevitably result in catastrophic rates of starvation and death (Amstrup et al. 2007; Crockford 2017, 2019), polar bears in the Svalbard region have so far not had any documented any harm to their health or population size. In fact, field data show bears in Svalbard are in better condition than they were in the late 1990s (Lippold et al. 2019), almost certainly due to the documented increase in primary productivity that has resulted from longer ice-free summers since 2003 (Frey et al. 2022; Crockford 2023).
Longer ice-free summers = more food
More open water exposed to summer sunlight has meant more food for fish, an advantage that has bumped up the food chain to ensure more seals for polar bears the following spring. Fatter bears produce healthier cubs that are more likely to survive their first year of life.
Barents Sea ice 2023
Barents Sea ice 2012
In recent years, sea ice has generally come late or not at all to Svalbard in the fall and most pregnant female polar bears can no longer make their maternity dens on the eastern islands (see map below).
However, there continues to be abundant denning habitat and fall sea ice around the Franz Josef Islands in Russia by at least late November (see chart below), which is still within the boundaries of the Barents Sea subpopulation. Being innately flexible, most Barents Sea bears now give birth or feed over the winter in the far-eastern portion of their range (Crockford 2019), and return to the ice off Svalbard in spring to feed on newborn seals.
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
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.
Crockford, S.J. 2023. The Polar Wildlife Report 2022. Global Warming Policy Foundation Briefing 63, London. pdf here.
Frey, K.E., Comiso, J.C., Cooper, L.W., et al. 2022. Arctic Ocean primary productivity: the response of marine algae to climate warming and sea ice decline. In: 2022 Arctic Report Card, NOAA. https://doi.org/10.25923/0je1-te61
Lippold, A., Bourgeon, S., Aars, J., et al. 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.
Regehr, E.V., Laidre, K.L, Akçakaya, H.R., et al. 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
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July 17, 2023 at 09:42PM
Iowa Climate Science Education 