Tag Archives: sea ice

New paper provides no evidence that polar bears ate whale carcasses to survive Eemian interglacial

Contrary to what the misleading press release implies, an entirely speculative new paper by polar bear specialists Kristin Laidre and Ian Stirling (among others) presents zero evidence that polar bear consumed whale carcasses during the last warm Interglacial (Eemian, ca. 115-130kya). And contrary to the impression that Eemian conditions were very challenging for polar bears, simulations from the single paleo sea ice simulation paper these authors cite show the ice-free season over most of the Eemian was less severe than today in the polar basin, with no reason for polar bears to scavenge extensively on large whale carcasses.

LaidreFEE_Wrangel Island scavenging_smaller

Polar bears are shown scavenging on the carcass of a dead bowhead whale that washed ashore on Wrangel Island, Russia. Credit: Chris Collins/Heritage Expeditions

This is yet another paper posing as science co-authored by Stirling that uses anecdotal accounts of behaviour to send a message about evolutionary capabilities of polar bears (Stirling and van Meurs 2015). With little or nothing to back it up, the paper’s real purpose is to convey Stirling’s opinion that past polar bear survival is irrelevant to understanding future polar bear survival — and that all the bears are gonna die unless we do something about carbon dioxide emissions generated by fossil fuel use.

Is it a coincidence that the Summary for Policy Makers was issued by the IPCC over the weekend (not the report with the science in it but the document that all politicians agreed were acceptable)? Look no further than the last sentence of National Geographic’s article on this story, which includes a quote from lead author Laidre and a link to the magazine’s interpretation of the new IPCC report:

“Laidre put it even more bluntly: “If you want polar bears around we need sea ice, and loss of sea ice closely tied to our activities and our fossil fuel emissions.” (Learn about the IPCC’s dire new climate report.)” 

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Now at least 10 years with sea ice at 2050-like levels yet polar bears are still abundant

We’ve hit the seasonal Arctic sea ice minimum for this year, called this morning by US NSIDC for 19th and 23rd of Septmeber: 4.59 mkm2, the same extent as 2008 and 2010. This is not a “ho-hum” year for polar bears: it means that since 2007, they have triumphed through 10 or 11 years1 with summer ice coverage below 5.0 mkm2 —  levels that in 2007 were expected to cause catastrophic declines in numbers.


Summer sea ice below 5.0 mkm2 were not expected to occur until about 2050, according to 2005/2006 sea ice models and polar bear specialists at the US Geological Survey (USGS). Polar bear survival models predicted 2/3 of the world’s polar bears would disappear when ice levels reached this threshold for 8 out of 10 years (Amstrup et al. 2007, 2008; Hunter 2007) but polar bears have been more resilient than expected (Crockford 2017, 2018; Crockford and Geist 2018). In fact, in many areas (like the Chukchi Sea, Barents Sea and Foxe Basin) polar bears are thriving despite dramatic declines in summer sea ice coverage (Aars et al. 2017; ACSWG 2018; Peacock et al. 2013; Regehr et al. 2016; Stapleton et al. 2016).

The sea ice models used to support the addition of polar bears to the US Endangered Species List as ‘threatened’ with extinction suggested sea ice levels from 3-5 mkm2 would not occur unti mid-century, yet they dropped before the ink was dry on the 2007 USGS Reports (ACIA 2005; Hassol 2004; Holland et al. 2006; Solomon et al. 2007; Zhang and Walsh 2006).

The ice extent charts from the University of Bremen (below) show ice that’s 50% concentration or greater at the date of the seasonal minimum (19th September): what polar bear specialists define as preferred habitat (Amstrup et al. 2007).


Compare the minimum shown above to the coverage predicted for 2050 and to coverage at the minimum in 2012 (the NSIDC image is here):

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Chukchi Sea polar bears number almost 3000 according to new survey results

The Chukchi Sea finally has a polar bear population estimate! According to survey results from 2016 only recently made public, about 2937 bears (1522-5944) currently inhabit the region, making this the largest subpopulation in the Arctic. This is exciting news — and a huge accomplishment — but the US Fish and Wildlife Service responsible for the work has been oddly mum on the topic.


Not only that, but an extrapolation of that estimate calculated by USFWS researchers for Chukchi plus Alaska (the US portion of the Southern Beaufort Sea subpopulation) was estimated at 4437 (2283-9527), although with “significant uncertainty.” Nevertheless, it means the 2016 estimate for Alaska could be roughly three times what it was in 2010: a whopping 1500 or so, up from about 450 (or about 225-650) for the same area estimated during the last survey (Bromaghin et al. 2015: Fig. 5a).

Even if the real number for Alaska is only twice as large (~1000), that’s still a huge improvement. It would eliminate the Southern Beaufort as the only polar bear subpopulation in the Arctic to have shown a significant decline blamed on human-caused global warming (Crockford 2018). If the recovery is real, it means the 2004-2006 decline was a temporary fluctuation after all, just like previous declines in the region. I expect, however, that it will take a dedicated SB population survey for officials to concede that point.

There is not yet a detailed report to cite (Regehr et al. in prep), but the numbers were announced at the 10th meeting of the Russian-American Commission on Polar Bears held at the end of July this year (AC SWG 2018) by Eric Regehr (formerly of the US Fish & Wildlife Service, as of 2017 at the University of Washington). [h/t to G.H.] This was the same report that raised the quota for subsistence hunting in the Chukchi from 58 to 85, based on these new figures, as I discussed last week.

Wrangel Island polar bear with cubs 2015 news story

From “Military bases to open on Wrangel Island and Chukotka” 22 October 2015.

Regehr was quoted as saying:

“Chukchi bears remain larger and fatter and have not seen downward trends in cub production and survival, according to new preliminary information on the health and numbers of bears.”

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White Lie: Polar bear starvation is virtually never caused by sea ice loss

Starvation due to natural causes is the leading cause of death for polar bears and loss of body condition (getting thinner) is therefore the first symptom of impending death for virtually all polar bears that die naturally. However, polar bear specialist Andrew Derocher claims that loss of body condition is also the first symptom of climate change for polar bears.


But how do you tell the difference between polar bears made thin by man-made climate change and those who are thin due to natural causes?

You can’t. Even a necropsy will not be conclusive because there are so many natural reasons for a bear to lose weight — and even starve to death — that’s it’s virtually impossible to say that any thin bear is skinny due to a lack of sea ice.

Emaciated polar bears like the one above from Somerset Island in the Canadian Arctic,1 captured on camera in August 2017, are being used to promote the idea that polar bears are already dying of starvation due to climate change. That’s a big white lie, as the headline above suggests: seven months later, National Geographic has admitted as much. Here I show why it could not have been true in the first place (with references from the scientific literature).

UPDATE: 29 August 2018: See my op-ed in the National Post (29 August 2018) and the GWPF video below on this issue:

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Facts contradict predictions that Chukchi Sea polar bears should be in trouble

Last fall, there were persistent alarms raised about low levels of sea ice in the Chukchi Sea that were echoed this spring. But these low ice levels are not really a serious concern for these polar bears: a 2018 assessment found the bears were in excellent health with no declines in cub production or survival. Funny how little we hear about that.

Wrangel Island polar bear with cubs 2015 news story

From “Military bases to open on Wrangel Island and Chukotka” 22 October 2015.

See a photo essay of Wrangel Island here and of the islands polar bears here and here.

You also don’t hear about the fact that sea ice has declined by about the same amount in the Chukchi Sea as in Western Hudson Bay. Since 1979, sea ice in the Chukchi Sea has declined at a rate similar to Western Hudson Bay (-0.90 days per year vs. -0.86 days per year, respectively), see graphs below from Regehr et al. (2016, Fig. 2):

Regher et al. 2016 fig 2 Barents and Chukchi Sea ice declineRegher et al. 2016 fig 2 Wh Bay ice decline

While Western Hudson Bay bear numbers have declined slightly in number (by a non-statistically significant amount) and appear to have suffered some recent declines in cub survival (Dyck et al. 2017) (with unsubstantiated claims of declines in adult body condition), Chukchi Sea bears have not (Rode and Regehr 2010; Rode et al. 2013, 2014, 2018).

The fact that Chukchi bears are thriving while Western Hudson Bay bears appear to be struggling, given almost identical trends in sea ice decline, is a connundrum that polar bear specialist are loath to explain.

Only last week, it was announced that the quota for subsistence hunting of Chukchi Sea polar bears had been raised from 58 to 85 due to the excellent status of the population. Polar bear biologist Eric Regehr was quoted as saying:

“Chukchi bears remain larger and fatter and have not seen downward trends in cub production and survival, according to new preliminary information on the health and numbers of bears.”

So, despite warnings from the polar bear and sea ice “experts” that Chukchi Sea bears may be in dire straits due to recent sea ice declines (see below), it appears that the bears themselves are more resilient to changing conditions than the experts give them credit.

NSIDC sea ice experts cruising the Chukchi Sea took this photo of a polar bear in excellent condition a couple of weeks ago (early August 2018, A. Khan), despite the scary-looking melt ponds:

Chukchi Sea polar bear Arctic_early August 2018_A Khan NSIDC

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Before National Geographic apologized for hyping the starving polar bear video they exploited it to promote a message of doom

Back in early February this year, National Geographic used their “this is what climate change looks like” video to promote a newly-published polar bear study and endorse conservation activist Steven Amstrup’s debunked and abandoned prediction of polar bear catastrophe due to global warming. Even with this revelation, the starving polar bear video fiasco is not yet over.

Baffin Island starving pb headline_GlobalNews_8 Dec 2017

Polar Bears Really Are Starving Because of Global Warming, Study Shows (National Geographic, 1 February 2018).

The initial focus of the February 2018 National Geographic article was a study published that week by Anthony Pagano and colleagues (Pagano et al. 2018; Whiteman 2018), suggesting that a few polar bears in the Southern Beaufort Sea were not getting enough to eat in early spring from 2014-2016 (with no reference to sea ice conditions; see my critique of that study here).

Then, Steven Amstrup, spokesman for activist organization Polar Bears International, is quoted as saying (my bold):

“If these results hold up [from Pagano’s study], then it shows that the loss of sea ice may have a bigger impact on the bears than previously thought, said Amstrup, a former USGS polar bear expert. Amstrup’s own 2010 study projected that continued decline in sea ice would reduce the global population of bears by two thirds, to less than 10,000 by 2050.

Seriously, no one except Amstrup and his Polar Bears International fanbase are citing his outlandish 2010 prediction, which is just a rehash of his 2007 USGS internal report and its 2008 journal version (Amstrup 2007, 2008, 2010). Amstrup’s prediction is not only a failure (Crockford 2017, 2018; Crockford and Geist 2018) but it’s been abandoned by his colleagues for vaguer or more moderate predictions of population decline (e.g. Atwood et al. 2015, 2016; Regehr et al. 2016).

National Geographic has now apologized for saying that the emaciated bear in the SeaLegacy video they so heavily promoted was “what climate change looks like” (and replaced the caption with “this is what starvation looks like,” even though there is no evidence the bear was starving from lack of food rather than from severe illness).

But the damage is done. By endorsing the discredited polar bear survival predictions of Amstrup along with the video, National Geographic degraded itself even further in the eyes of rational and informed readers. I’ll have more to say on the SeaLegacy video exploited by National Geographic and its message that starving polar bears are victims of climate change in a subseqent post: we haven’t yet reached the end of this debacle.


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., Marcot, B.G., Douglas, D.C. 2008. A Bayesian network modeling approach to forecasting the 21st century worldwide status of polar bears. Pgs. 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. http://onlinelibrary.wiley.com/doi/10.1029/180GM14/summary and http://alaska.usgs.gov/science/biology/polar_bears/pubs.html

Atwood, T.C., Marcot, B.G., Douglas,D.C., Amstrup, S.C., Rode, K.D., Durner, G.M. and Bromaghin, J.F. 2015. Evaluating and ranking threats to the long-term persistence of polar bears. USGS Open-File Report 2014–1254. Pdf here.

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.

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.

Crockford, S.J. and Geist, V. 2018. Conservation Fiasco. Range Magazine, Winter 2017/2018, pg. 26-27. Pdf here.

Pagano, A.M., Durner, G.M., Rode, K.D., Atwood, T.C., Atkinson, S.N., Peacock, E., Costa, D.P., Owen, M.A. and Williams, T.M. 2018. High-energy, high-fat lifestyle challenges an Arctic apex predator, the polar bear. Science 359 (6375): 568 DOI: 10.1126/science.aan8677

Whiteman, J.P. 2018. Out of balance in the Arctic. Science 359 (6375):514-515. http://science.sciencemag.org/content/359/6375/514

Sea ice silly season: Wadhams spouts fake facts about polar bears of northern Greenland

As the seasonal minimum for Arctic sea ice approaches, the media get carried away by hyperbole. Tha’t been true since 2007. This year, other outlets will need to work hard to beat yesterday’s bit of nonsense from The Independent trying to out-do The Guardian: it not only includes false polar bear facts (from sea ice researcher Peter Wadhams) but leads with last year’s controversial SeaLegacy video of an emaciated polar bear. Sea ice silly season has truly begun.

East Greenland Scorsby Sound March 2011 on Kap Tobin_Rune Dietz_press photo

Wadhams (described as “one of the UK’s leading sea ice scientists” although not a particularly respected one) was interviewed about the small area of open water that opened up over the last few days in northern Greenland (see NSIDC photo below), driven by offshore winds (not melt). This region is the eastern-most part of the area that is considered the “last holdout” for Arctic sea ice: an immense band of very thick (4-20m) multiyear ice that stretches across the Arctic Ocean shores of the Canadian Arctic Archipelago.

The open water is expected to last a few days at most but Wadhams was absolutely breathless with dire warnings of what this might mean for the future of polar bear in the region (about which he knows nothing), rhetoric ramped up even further by the news outlet with quotes from co-director of the Grantham Institute (London), Martin Siegert, and predictions on how low the sea ice minimum might be.

Greenland north open water_13 Aug 2018 NASA_NSIDC 15 Aug 2018 report

Cape Morris Jesup on 13 August 2018. W. Meier, NSIDC/NASA.

I think this is a truly spectacular example of the ignorance of scientists speaking outside their area of expertise used to mislead the public but decide for yourself.

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