Susan Crockford
All predictions of catastrophe apart, the truth is the polar bear is no nearer to extinction than it was in 2005 as Arctic sea ice once more steadfastly resists slipping previous a catastrophic ‘tipping level’ — or the ‘demise spiral’, as some chicken-littles proceed to name it.
The truth is, the summer season sea ice development has been just about flat since 2007, with ice protecting about 42% much less space than it had completed in 1979, but polar bears in lots of areas are doing higher now than they have been in 2005, particularly in Davis Strait, the Barents and Chukchi Seas and the Canadian Arctic Archipelago.
No ‘tipping level for Arctic summer season sea ice
The U.S. Nationwide Oceanic and Atmospheric Affiliation (NOAA) identifies three durations in sea ice minimums: From 1979 to 1992, sea ice loss declined about 6% per decade. From 1993 to 2006, the decline accelerated to 13.3%. However from 2007 to 2020, the slope softened to simply 4%. MongaBay Information, 15 July 2021.
That flattish development has solely continued, because the graph beneath exhibits, modified from one revealed by the US Snow and Ice Knowledge Middle (NSIDC) in 2019 — see unique right here — exhibiting the September common (not the minimal extent), so whereas we don’t have the determine but for 2022 it’s more likely to be near what it was in 2021:
Sea ice minimal at 2022
The NSIDC reported yesterday that Arctic sea ice reached its minimal extent on 19 September this 12 months, protecting 4.68mk2. The College of Bremen (see chart beneath) measured the extent at 4.87mk2 on this date however the slight distinction is just not actually vital: the form and aerial extent of ice protection at this date in comparison with 2005 are what I’m emphasizing right here.
Sea ice minimal at 2005
The minimal extent of ice protection was reached on 22 September in 2005 (U. Bremen):
Prediction based mostly on 2005 sea ice situations
Half of the predictions of future sea ice protection (for 2050) have been already exceeded by 2007 and the authors of the 2007 USGS conservation report on polar bears (Amstrup et al. 2007) acknowledged: “This implies our projections for the longer term standing of polar bears could also be conservative.” In different phrases, Amstrup and colleagues thought the longer term would in all probability be even worse than they predicted of their report: that much more than 2/3 of the world’s polar bears can be misplaced by 2050.
15 steady years of 42% much less summer season sea ice
Because the graph beneath from Stroeve and colleagues exhibits, the fashions of summer season Arctic sea ice loss used to foretell the dire future for polar bears have been, by 2007, quickly deviating from observations: it was certainly worse than they thought!
Because it occurred, the polar bear specialists have been improper (Crockford 2017, 2019): polar bears have been extra versatile and resilient than predicted and after 15 years of summer season sea ice dropping to ‘catastrophic’ ranges (about 42% much less ice than in 1979 for a minimum of 8 years out of 10), many subpopulations of the bears are higher off than earlier than. Davis Strait, Barents Sea and Chukchi Sea bears are doing very effectively: Barents Sea bears particularly are thriving regardless of by far probably the most sea ice lack of any Arctic area (e.g. Lippold et al. 2019; Peacock et al. 2013; Regehr et al. 2018; Rode et al. 2014). This was not what had been predicted.
Conclusion: Regardless of the Arctic warming 4 instances as quick as the remainder of the world with rising CO2 ranges and about 42% much less summer season ice than there was in 1979, there may be presently no ‘local weather emergency’ for polar bears and the species is no nearer to extinction than it was 15 years in the past.
References
Amstrup, S.C., Marcot, B.G. & Douglas, D.C. 2007. Forecasting the rangewide standing of polar bears at chosen instances within the twenty first century. US Geological Survey. Reston, VA. Pdf right here
Crockford, S.J. 2017. Testing the speculation that routine sea ice protection of 3-5 mkm2 ends in a higher than 30% decline in inhabitants dimension of polar bears (Ursus maritimus). PeerJ Preprints 19 January 2017. Doi: 10.7287/peerj.preprints.2737v1 Open entry. https://peerj.com/preprints/2737/
Crockford, S.J. 2019. The Polar Bear Disaster That By no means Occurred. International Warming Coverage Basis, London. Out there in paperback and book codecs.
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 developments of persistent natural pollution in Barents Sea polar bears (Ursus maritimus) in relation to modifications in feeding habits and physique situation. Environmental Science and Technology 53(2):984-995.
Peacock, E., Taylor, M.Okay., Laake, J. & Stirling, I. 2013. Inhabitants ecology of polar bears in Davis Strait, Canada and Greenland. Journal of Wildlife Administration 77:463–476.
Regehr, E.V., Hostetter, N.J., Wilson, R.R., Rode, Okay.D., St. Martin, M., Converse, S.J. 2018. Built-in inhabitants modeling offers the primary empirical estimates of significant charges and abundance for polar bears within the Chukchi Sea. Scientific Studies 8 (1) DOI: 10.1038/s41598-018-34824-7 https://www.nature.com/articles/s41598-018-34824-7
Rode, Okay.D., Regehr, E.V., Douglas, D., Durner, G., Derocher, A.E., Thiemann, G.W., and Budge, S. 2014. Variation within the response of an Arctic prime predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations. International Change Biology 20(1):76-88. http://onlinelibrary.wiley.com/doi/10.1111/gcb.12339/summary
Stroeve, J., Holland, M.M., Meier, W., Scambos, T. and Serreze, M. 2007. Arctic sea ice decline: Quicker than forecast. Geophysical Analysis Letters 34:L09501. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2007GL029703
