Tag Archives: sea ice

Late winter polar bear habitat 2017 vs. 2006 and 2011 shows no trend

Here is a bit of historical perspective for rational readers trying to make sense of the doom-mongering of others that current sea ice conditions spell trouble for polar bears, given that the winter maximum extent for 2017 reached a new seasonal low (keeping in mind that NSIDC does not publish error bars for these measurements, which helps elevate such pronouncements to “news”).

Ice extent (courtesy NSIDC’s MASIE) at 25 March (Day 84) is below for 2017, 2011 and 2006, almost 3 weeks after the winter maximum was declared at 7 March for 2017, 9 March for  2011, and 12 March for 2006. Extent at the maximum for 2006 was estimated at 14.68 mkm2, 14.42 mkm2 for 2017, and 14.67 mkm2 in 2011 (what tiny differences make headlines these days).

Remember: there are no polar bears in the Sea of Okhotsk or in the Baltic Sea (marked with an * below) yet ice in those regions is included in the Arctic totals used to determine maximum seasonal extent. Much (and sometimes, all) of the “Arctic” variation in extent at this time of year is accounted for by variation in Sea of Okhotsk and Baltic Sea coverage.

Sea ice day 84 March 25 2017_2011_2006 labeled

Bottom line: total winter ice extent for the Arctic ≠ winter polar bear habitat and neither have changed much in a decade.

See close up of the above graphic below.

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Another fat bear onshore in late winter, along Gulf of St. Lawrence north coast

Another fat bear onshore in late winter, this time along the Quebec shore of the Gulf of St. Lawrence (22 March 2017) – and this time, one of the witnesses to the sighting took some great photos. Courtesy CBC News (Polar bear makes rare appearance on Quebec’s Lower North Shore 24 March 2017).

Gulf St Lawrence North shore PB visit 22 March 2017_CBC headline

Quotes, location map, and sea ice charts below.

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Science behind the video Polar Bear Scare Unmasked – updated paper now available

Announcing the publication today of Version 3 2 of my paper that tests the hypothesis that polar bear population declines result from rapid declines in summer sea ice, updated with recently available data. Version 2 provides the scientific support for the information presented in the GWPF video published yesterday, “Polar Bear Scare Unmasked: The Sage of a Toppled Global Warming Icon” (copied below).


[The graphic above was created by me from the title page and two figures from the paper]

Updated 1 March 2017: I added an important reference to the paper below that got overlooked in previous versions (the work of Armstrong et al. 2008, see this post), making Version 3 the latest and most up-to-date.

Crockford, S.J. 2017 V3. 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

Version 3, published 2 March 2017, adds an important reference; Version 2, published 28 February, incorporates additional reviewer comments and suggestions received on Version 1, as well as the updates noted above.

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Polar Bear Scare Unmasked: The Saga of a Toppled Global Warming Icon [video]

For more than ten years, we’ve endured the shrill media headlines, the hyperbole from conservation organizations, and the simplistic platitudes from scientists as summer sea ice declined dramatically while polar bear numbers rose.

Now, just in time for International Polar Bear Day, there’s a video that deconstructs the scare. It runs about 8 minutes, written and narrated by me, produced by the Global Warming Policy Foundation.

Polar Bear Scare Unmasked: The Saga of a Toppled Global Warming Icon

Update 28 February 2017 See my follow-up post for the science behind the video, featuring a new version of my sea ice/polar bear hypothesis paper, just published.

Crockford, S.J. 2017 V2. 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 28 February 2017. Doi: 10.7287/peerj.preprints.2737v2 Open access. https://peerj.com/preprints/2737v2/ [make sure you select Version 2, noted on title page]

Global polar bear population larger than previous thought – almost 30,000

The results of three recently-released studies that were not included in the last IUCN Red List assessment add more than 2,050 bears (on average)1 to the official 2015 global polar bear estimate, a point you won’t likely hear next Monday (27 February) from most polar bear specialists, conservation organizations, their cheerleaders and corporate sponsors on International Polar Bear Day.


This means the adjusted 2015 global estimate for polar bears should be about 28,500 (average), a significant increase over the official estimate of 26,500 (average) for 2015 — and an even larger increase over the 2005 estimate of about 22,500 (average)2, despite the dramatic loss of summer sea ice since 2007 that we hear about endlessly.

It is increasingly obvious that polar bears are thriving despite having lived through summer sea ice levels not predicted to occur until 2050 – levels of sea ice that experts said would wipe out 2/3 of the world’s polar bears (Amstrup et al. 2007; Crockford 2017 v3).

A result, I have been remiss to point out [updated 28 Feb. 2017 & included in revised Version 3 of Crockford 2017], that Drs. Kesten Green, Scott Armstrong and Willie Soon correctly concluded in 2008 was a likely outcome. In their 2008 paper that roundly criticized the USGS forecasting methods used to support placing polar bears on the US Endangered Species List (Armstrong et al. 2008:390), they concluded:

“Given the upward trend in polar bear numbers over the past few decades, a modest upward trend is likely to continue in the near future because the apparent cause of the trend (hunting restrictions) remains.”

So when you hear, “Save the polar bears, their future is grim” next week, remember that polar bears are thriving right now because those future predictions were flawed: summer sea ice is not critical habitat for polar bears. Instead of a vacuous “vanishing species” polar bear T-shirt from WWF, buy Polar Bear Facts and Myths for the kids in your life – and Polar Bears: Outstanding Survivors of Climate Change for your home or community library. You’ll be glad you did.


1. Total for all three estimate increases is 2054, or about 2050.
Barents Sea (BS) estimated at 3749 for entire region, up 42% (1109) since 2004 estimate of 2640, based on 42% Svalbard increase determined in 2015 (Norwegian Polar Institute 2015; Crockford 2017 v2) applied across the region. This is consistent with observations in 2004 that researchers found about three times (2.87) as many bears in the Russian sector than in Svalbard (Aars et al. 2009), and the stated expectation by Norwegian biologists that the population size would continue to increase despite declines in sea ice (Fauchald et al. 2014).

Baffin Bay (BB) estimate 2,826 (95% CI = 2,059-3,593) at 2013 (SWG 2016), up 752.

Kane Basin (KB) estimate 357 (95% CI: 221 – 493) at 2013 (SWG 2016), up 193.

2. USGS polar bear biologists (Amstrup et al. 2007) used a figure of 24,500 for the global population size in 2005 to support their prediction of doom at mid-century that put polar bears on the US Endangered Species List (Crockford 2017 v2). If we use that figure instead of the average of “20,000-25,000” the increase at 2015 (with the amended data) is still a remarkable 16%.

Update 26 Feb 2017. Original image replaced, without % calculation.

Update 1 March 2017. Crockford 2017 updated, Version 3 is now the most recent available.


Aars, J., Marques, T.A., Buckland, S.T., Andersen, M., Belikov, S., Boltunov, A., et al. 2009. Estimating the Barents Sea polar bear subpopulation. Marine Mammal Science 25:35-52.

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. 8.8 MB pdf here [may no longer be available online]

Armstrong, J.S., Green, K.C. and Soon, W. 2008. Polar bear population forecasts: A public-policy forecasting audit. Interfaces 38:382–405.

Crockford, S.J. 2017 v3. 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

Fauchald, P., Arneberg, P., Berge, J., Gerland, S., Kovacs, K.M., Reigstad, M. and Sundet, J.H. 2014. An assessment of MOSJ – the state of the marine environment around Svalbard and Jan Mayen. Norwegian Polar Institute Report Series no. 145. Available at http://www.mosj.no/en/documents/

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

Polar bear habitat update: Masie charts show more ice in 2017 than 2006

It’s just an observation but NSIDC Masie ice charts show 14.7 mkm2 of sea ice for 2017 at 19 February (Day 50) but only 14.3 mkm2 for 2006 (see them copied below).

In contrast, the NSIDC interactive graph shows almost the opposite: 14.3 mkm2 for 2017 and 14.4 mkm2 for 2006 (but with both below 2 standard deviations of average).


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Polar bear habitat update for Canada at mid-February

Mid-February is the tail end of the winter fast for polar bears. Sea ice is approaching it’s maximum global extent but local maximum extents may vary. Most of the sea ice in Canada is locked in already but two regions still vary at this time of year: the Labrador Sea off Labrador and Newfoundland – where polar bears come to feed on an abundance of newborn harp seals – and the Gulf of St. Lawrence, where polar bears have not been spotted in more than 60 years. sea-ice-extent-canada-2017-feb-14_cis

There is almost certainly enough ice for harp seals to give birth in the Gulf this year, if the ice holds (despite some premature hand-wringing by seal biologists). There is more ice in the Gulf and off Newfoundland this year than there was in 2013 (see map below). Continue reading