Tag Archives: threatened

Abrupt summer sea ice decline has not affected polar bear numbers as predicted

Yes, Arctic sea ice has declined since satellite records began in 1979 but polar bears have adjusted well to this change, especially to the abrupt decline to low summer sea ice levels that have been the norm since 2007.

Global pb population size sea ice 2017 July PolarBearScience

Some polar bear subpopulations have indeed spent more time on land in summer than in previous decades but this had little negative impact on health or survival and while polar bear attacks on humans appear to have increased in recent years (Wilder et al. 2017), the reasons for this are not clear: reduced summer sea ice is almost certainly not the causal factor (see previous post here).

Ultimately, there is little reason to accept as plausible the computer models (e.g. Atwood et al. 2016; Regehr et al. 2016) that suggest polar bear numbers will decline by 30% or more within a few decades: even the IUCN Red List assessment (Wiig et al. 2015) determined the probability of that happening was only 70%.

Arctic sea ice has never been a stable living platform (Crockford 2015): it shifts from season to season, year to year, and millennia to millennia. Without the ability to adapt to changing conditions, Arctic species like polar bears and their prey species (seals, walrus, beluga, narwhal) would not have survived the unimaginably extreme changes in ice extent and thickness that have occurred over the last 30,000 years, let alone the extremes of sea ice they endured in the last 200,000 years or so.

Some biologists continue to hawk doomsday scenarios for polar bears due to summer sea ice loss but the truth is that their previous predictions based on sea ice declines failed so miserably (e.g. Amstrup et al. 2007) that it’s impossible to take the new ones seriously — especially since the basic assumptions that caused the first predictions to fail have not been corrected, as I’ve stated in print (Crockford 2017:27):

In summary, recent research has shown that most bears are capable of surviving a summer fast of five months or so as long as they have fed sufficiently from late winter through spring, which appears to have taken place since 2007 despite marked declines in summer sea ice extent.

The assumption that summer sea ice is critical feeding habitat for polar bears is not supported.

Recent research shows that changes in summer ice extent generally matter much less than assumed in predictive polar bear survival models of the early 2000s as well as in recent models devised to replace them (Amstrup et al. 2010; Atwood et al. 2016a; Regehr et al. 2015; Regeher et al. 2016; Wiig et al. 2015), while variations in spring ice conditions matter more.

As a consequence, the evidence to date suggests that even if an ‘ice-free’ summer occurs sometime in the future ­ defined as sea ice extent of 1 million km2 or less (Jahn et al. 2016) ­ it is unlikely to have a devastating impact on polar bears or their prey. [my bold]

The abrupt drop in summer sea ice that occurred in 2007 was not predicted by experts to occur until mid-century yet the predicted decimation of polar bears worldwide expected under those conditions (a loss of 2/3 of the global total, to only about 6660-8325 bears) not only did not happen, it did not come even close to happening (Crockford 2017; see also my recent books, Polar Bear Facts & Myths, and Polar Bears: Outstanding Survivors of Climate Change, sidebar).

Instead, the global population grew from about 22,550 bears in 2005 to about 28,500 bears in 2015. And while this might not be a statistically significant increase (due to the very wide margins of error for polar bear estimates), it is absolutely not a decline.

The present reality is that low summer sea ice cover since 2007 has not caused polar bear numbers to decline and therefore, polar bears are not a species in trouble. This suggests that even if the Arctic should become briefly ice-free in summer in the future, polar bears are likely to be only minimally affected and not become threatened with extinction. Polar bears are outstanding survivors of climate change: recent research and their evolutionary history confirm this to be true.

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USGS ‘treadmill’ paper repeats bogus claim that ice loss harmed polar bears

The newest polar bear science paper making the rounds courtesy the US Geological Survey, is a perfect example of a statistically-significant result with no biological significance. While the results are rather lame, the paper is dangerous because it repeats the disingenuous claim (see Crockford 2017) that Southern Beaufort Sea polar bear numbers declined in recent years due to summer sea ice loss.

polar_bear_rubble_ice_Mike Lockhart USGS_8 April 2011

The USGS authors (Durner et al. 2017) know this harm-from-summer-ice-loss assertion is not true for the Southern Beaufort subpopulation but the more papers they can get into print that say so, the more likely it will be believed — and the less likely readers will check older literature that documents the recent decline in polar bear numbers was due to a three year period (2004-2006) when thick ice conditions in spring made seal hunting a challenge, a repeat of a well-known phenomenon (e.g. Stirling et al. 1980; Stirling 2002) unique to this region that has been documented since the 1960s.

The Durner paper (USGS press releaseIncreased Sea Ice Drift Puts Polar Bears on Faster Moving Treadmill” published online 6 June ahead of print) spins the research results as potentially significant bad news but in so doing reveals how desperate they have become to make the public and their biology colleagues believe that Southern Beaufort polar bears, among others, are being negatively affected by summer sea ice loss (as per Stirling and Derocher 2012).

Durner, G.M., Douglas, D.C., Albeke, S.E., Whiteman, J.P., Amstrup, S.C., Richardson, E., Wilson, R.R. and Ben-David, M. 2017. Increased Arctic sea ice drift alters adult female polar bear movements and energetics. Global Change Biology. DOI: 10.1111/gcb.13746 http://onlinelibrary.wiley.com/doi/10.1111/gcb.13746/abstract [paywalled]

In fact, the Durner et al. paper does not document any harm to polar bears from the proposed ‘treadmill’ effect of more rapidly moving ice for the period 1999-2013 compared to 1987-1998, but instead uses models to suggest bears might have to eat one to three more seals per year to compensate for the extra energy needed to walk against the moving ice. That’s right: perhaps only 1 more seal per year out of the 50 or so they would usually consume (see Stirling and Øritsland 1995). In my opinion, that’s a pretty lame result for what one of the co-authors described as an immense amount of work.

News outlets have essentially used the USGS press release as a click-bait lede for another round of Trump-bashing with respect to the Paris climate change agreement, see here and here: the stories are hardly about polar bears at all. And predictably, polar bear activist and co-author Steven Amstrup (paid spokesperson for Polar Bears International, famous for their “Save Our Sea Ice” campaign) appears to be using the same approach: an up-coming call-in talk radio program at NPR’s Anchorage affiliate KSKA for Tuesday 13 June at 10:00 (Alaska time, see “Talk of Alaska”) is being billed as a discussion of “polar bears, climate change, and the Paris Accord” (h/t AK geologist). Continue reading

Global polar bear population size is about 28,500 when updates are included

Polar bear numbers have risen since 2005, no matter how you look at it:

Svalbard polar bear Jon Aars_Norsk Polarinstitutt

USGS estimated 24,500 (average) polar bears in 2005.

IUCN estimated 26,500 (average of 22,000-31,000) in 2015
(assessment completed in July, released in November).

Subpopulation surveys completed or reported after July 2015 (Baffin Bay, Kane Basin, Barents Sea) added ~2,000 bears.

This brings the adjusted average total at 2015 to ~28,500.

This may not be a statistically significant increase but it is also not the catastrophic decline that was predicted to occur in association with the abrupt drop of summer sea ice in 2007 to a new average of about 3-5 mkm2 [updated 1 June 2017].

Crockford 2017_Slide 12 screencap

Explained in full in this published paper, pgs 20-21:

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


Thriving numbers – & two great books – are ample reason to rejoice on Polar Bear Day

Ten years of summer sea ice levels expected to kill 2/3 of the world’s polar bears by 2050 instead saw polar bear numbers grow. And this year, there are also two fabulous books about polar bears and their outstanding success story to celebrate on International Polar Bear Day (Monday 27 February 2017).


One is suitable for kids (Polar Bear Facts & Myths) and another for adults and teens who want the details (Polar Bears: Outstanding Survivors of Climate Change) – see the right sidebar to buy on Amazon or my author website for details on all additional formats. A couple of excerpts from them are below.

So forget turning down your thermostat in a pointless gesture to “reduce your carbon emissions and help polar bears” — as Polar Bears International advocates for Polar Bear Day. Instead, treat yourself or a friend and order a book with a rational approach to species survival.

Speaking of species survival, think about the inconsistency in how some species are treated according to the US Endangered Species Act (ESA). Humpback whale numbers recovered after decades of protection; in 2016, after the state of Alaska filed a petition to delist, most populations were officially removed from the ESA list of ‘threatened’ species.


Humpback whale and calf, NOAA image.

In contrast, by 2015, polar bear numbers had also recovered despite years of low sea ice loss not predicted until 2050, yet remain officially ‘threatened’ with extinction.


Fat bear family at Kaktovik, Alaska (Southern Beaufort), April 2016. USGS photo.

US National Marine Fisheries Service defended the delisting of humpback whales against activists who insisted human-caused global warming threatened the species, but the US Fish and Wildlife Service defends flawed polar bear prophesies.

My books lay out the polar bear success story: in simple form for younger readers and in detail for others. See the excerpts below.


Polar bears have not been driven to the brink of extinction by global warming. In fact, they are thriving (see my final conclusions on pg. 30 of Polar Bears: Outstanding Survivors of Climate Change, above and pg. 32 of Polar Bear Facts & Myths below.


If you’d like to support my efforts to bring this to everyone’s attention, please consider buying a copy or two of my books. If you’ve already done so, keep in mind that your local library might be glad to have copies donated. They also make great gifts.



New paper asks: Has recent sea ice loss caused polar bear populations to crash?

A paper published today finds that predictions of polar bear population crashes due to summer sea ice loss are based on a scientifically unfounded assumption.


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

Specifically, this paper of mine addresses the basic premise upon which predicted population declines linked to modeled habitat loss made by polar bear specialists back in 2006 and 2008 (by the International Union for the Conservation of Nature, IUCN, and the US Fish and Wildlife Service, USFWS), and concludes that when assessed as a testable hypothesis against data collected since then, it must be rejected.

The forum for this paper is PeerJ Preprints,  which I found while looking for recent research papers about ringed seals. I discovered that Canadian ringed seal biologist Steven Ferguson recently used this service, which is free, open access, accepts review commentary, and will show up on Google and Google Scholar searches.

Ferguson et al. 2016. Demographic, ecological and physiological responses of ringed seals to an abrupt decline in sea ice availability. DOI:10.7287/peerj.preprints.2309v1 Pdf here. https://peerj.com/preprints/2309/

I decided that if this publication forum was good enough for Ferguson and his Arctic research community, it was good enough for me.

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/  (pdf here).

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Fake news on polar bear survival predictions is political posturing

I call this fake news because it’s not news – media headlines around the world today (New York Times, Washington Post, DailyMail) are trumpeting the release of a final version of a draft report released with similar fanfare more than a year ago, announced today by the US Fish & Wildlife Service in the official US government publication, Federal Register.


Without action on climate change, say goodbye to polar bears” is exactly the kind of sensationalized nonsense I address in my new detailed science book, Polar Bears: Outstanding Survivors of Climate Change (announced here, discussed here).
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Communicating polar bear science requires a rational approach

My most requested public lecture, Polar Bears: Outstanding Survivors of Climate Change, has been hugely popular with audiences in my Canadian home town of Victoria, British Columbia, and my newly-released book with the same title (based on that lecture) promises to be similarly successful. Here are some thoughts on both.


Recently (5 January 5, 2017), I gave another free lecture about polar bears to a local non-profit organization through my university’s Speakers Bureau. I’ve been doing this since 2009, although the shear volume of requests has been much higher this past year than previously. As before, my lecture was warmly received and audience members asked questions indicating they had been listening with an open mind. A colleague I spoke to expressed surprise at that outcome, given where I live.

Keep in mind that Victoria is home to litigation-prone IPCC climate scientist turned BC provincial Green Party politician Andrew Weaver (in whose riding I happen to reside) as well as one of the many targets of fake Nobel Laureate Michael Mann and his over-sensitive ego, veteran climate scientist Tim Ball (who defends the defamation lawsuit filed against him by Mann at trial in Vancouver, B.C. 20 February 2017,  an event which defender of free speech and fellow defendant against Mann’s litigious wrath, Mark Steyn,  has said he’ll be attending). And yes, in a sort of home-town science brawl, Weaver also sued Tim Ball, but that case has not yet gone to court. Victoria is also the constituency of our lone federal Green Party Member of Parliament, Elizabeth May. Canadian journalist Donna Laframboise once described Victoria as “one of the most left-leaning corners of the country.

So it is into this virtual lion’s den of anthropogenic global warming champions that I venture, several times a month, to enlighten adults, teachers, and students who have been left with the impression that there are only a few hundred starving polar bears left in the world.1

The secret to the kind of reception I receive – even in my town – is to present the relevant facts without emotional overtones and let audiences make up their own minds about what they think of the situation.

This latest lecture was not only well received but several audience members bought copies of my kid-friendly Polar Bear Facts and Myths that I had for sale (reviewed here by Kip Hansen).  One member came up afterwards to say he’d been dreading what he’d anticipated would be another polar-bears-are-doomed diatribe but was very pleased at my even-handed, scientific approach.

That’s why I decided to fashion my first fully referenced polar bear science book – and take it’s title – from my most successful public lecture. Audience responses over the years indicated to me that a simple summary would be an appealing approach. Questions from audience members over the years suggested which topics might need a more detailed explanation in the book. The lesson I learned from my lecturing experience was that my book needed a focused style, plenty of color images, and an affordable price.

Consider the table of contents for the new book, where each chapter covers only a few pages:

1. Polar bear & sea ice basics
2. Feasting/fasting life of polar bears
3. Evolution & climate change
4. Conservation & protection
5. Failure of the polar bear predictions
6. Biggest threat to polar bears
7. Summary
8. Conclusions

I expect I’ll get some negative fake reviews posted on Amazon for Polar Bears: Outstanding Survivors of Climate Change from the self-appointed moral-high-ground troll network (as they did for Polar Bear Facts and Myths). That’s to be expected for a topic like this. Honest criticism from readers might also be generated, of course, and that’s something all writers can expect, and should welcome.

That said, the best way to counter biased or unconstructive reviews is with honest, heartfelt reviews from readers who have actually read the book. If any of you that have ordered a copy of this book but would like to see a pdf review document in order to post an immediate review, use the contact me form at “Comments/Tips.”

Both Polar Bears: Outstanding Survivors of Climate Change and Polar Bear Facts and Myths are now available in paperback and various ebook formats, including epub and pdf. The little spin-off for preschoolers (Polar Bears Have Big Feet) – because why shouldn’t the little kids have a fear-mongering-free polar bear book with great pictures too? – is available in paperback only.


  1. Without exception, every teacher of every school class I have spoken to in Victoria in the past year has been absolutely astonished to learn that the official global population estimate for polar bears is now 22,000-31,000, the highest estimate in 50 years. Virtually all expressed their appreciation for pointing out that simple fact. Hence, Polar Bear Facts and Myths is aimed at those misinformed children, while Polar Bears: Outstanding Survivors of Climate Change is aimed at their teachers, parents, and other influential relatives.