Tag Archives: observations

Amstrup & colleages can’t refute my critique of their 2007 polar bear survival model, Part 2

Polar bear specialists Andrew Derocher and Steven Amstrup recently spent inordinate energy trying to refute the opinion piece I’d written for the Financial Post in celebration of International Polar Bear Day last month, ignoring my fully referenced State of the Polar Bear Report for 2017 that was released the same day (Crockford 2018) and the scientific manuscript I’d posted last year at PeerJ Preprints (Crockford 2017).

polar_bear_USFWS_fat Chukchi Sea bear

Their responses use misdirection and strawman arguments to make points. Such an approach would not work with the scientific community in a public review of my paper at PeerJ, but it’s perfect spin for the self-proclaimed “fact-checking” organization called Climate Feedback. The result is a wildly ineffective rebuttal of my scientific conclusion that Amstrup’s 2007 polar bear survival model has failed miserably.

This is Part 2 of my expose, see Part 1 here.
Continue reading

Polar bear numbers not declining despite media headlines suggesting otherwise

In scanning comments generated by the recent flurry of internet interest in polar bears and blogs I noticed that a good many people, fed alarming media stories, are still convinced that polar bear numbers are declining rapidly when nothing could be further from the truth.

Crockford 2017_Slide 12 screencap

Continue reading

Science, optimism, and the resilience of polar bears in an ever-changing Arctic

Optimism in conservation science — which the Smithsonian says we desperately need (Earth Optimism Summit 21-23 April 2017, apparently a huge success) — means it’s time to acknowledge and celebrate real conservation success stories. The Smithsonian folks probably won’t say it but I will — one of those successes is the recovery of polar bears.

Female with cub_Shutterstock_PolarBearScienceIt’s time to abandon the focus on prophesies of impending loss and accept that recovery of polar bears from the over-hunting of last century has continued despite a decade of low summer sea ice (Aars et al. 2017; Crockford 2017; Dyck et al. 2017; SWG 2016; York et al. 2016). Why not focus on the numerous images of fat, healthy bears rather than the anomalous starving ones?

It’s time to let go of imagined future catastrophes based on pessimistic failures of adaptation (Amstrup et al. 2007, 2008; Atwood et al. 2016; Stirling and Derocher 2012) and acknowledge that polar bears and Arctic seals, just like Pacific walrus (MacCracken et al. 2017; US Fish & Wildlife Service 2017), are resilient species with adaptive capabilities we are are only just beginning to comprehend (Crawford and Quakenbush 2013; Crawford et al. 2015; Escajeda et al. 2018; Rode et al. 2014; Stirling and Lunn 1997; Stirling et al. 1975a; Vibe 1965). Continue reading

Consensus polar bear experts dealt with criticism differently in 2007

Frustration with criticism over the fate of polar bears decades into the future has plagued consensus experts since they first brought their concerns to the attention of conservation organizations in the mid-2000s. But now that catastrophe has not materialized, these researchers have shifted their defensive style from logical reasoning to relentless insult.

Dealing with criticism 2007 vs 2017

A decade ago, doubts about the veracity of the proposed ESA conservation status of “threatened” with extinction due to predicted effect of global warming came primarily through the media, who were seen to give critics a platform.

In a revealing article published 10 years ago in the fall of 2007 (before the ESA decision had been made) by polar bear biologists Ian Stirling and Andrew Derocher (“Melting Under Pressure: The real scoop on climate warming and polar bears”) in The Wildlife Professional, some of the same concerns were being raised as in 2017 by Harvey and colleagues (that including Stirling and fellow polar bear biologist Steven Amstrup) in BioScience (“Internet blogs, polar bears, and climate-change denial by proxy”), but the approach and the language is startlingly different.
Continue reading

Twenty reasons not to worry about polar bears, the 2017 update

Cover image_Twenty Reasons_polarbearscienceJust in time for Polar Bears International’s self-proclaimed fall Polar Bear Week (5-11 November 2017), here’s a new resource for cooling the polar bear spin. I’ve updated my 2015 summary of reasons not to worry about polar bears, which is now more than two years old. In this new version, you will find links to supporting information, including published papers and fully referenced blog posts of mine that provide background, maps and bibliographies, although some of the most important graphs and maps have been reproduced here. I hope you find it a useful resource for refuting the pessimism and prophecies of catastrophe about the future of polar bears. Please feel free to share it.

As global leaders meet in Bonn for COP23 (6-17 November 2017), it’s time to celebrate the proven resilience of polar bears to their ever-changing Arctic environment.

Twenty Reasons: the bullet points

  1. Polar bears are still a conservation success story: there are more polar bears now than there were 40 years ago.
  2. Fewer populations are in decline than in 2010 (only one, officially) and only six are data deficient (down from nine).
  3. Abrupt summer sea ice decline has not affected polar bear numbers as predicted: even though sea ice levels dropped to mid-century levels in 2007, the expected decimation of polar bears failed to occur.
  4. The Chukchi Sea population is thriving despite a pronounced lengthening of the ice-free season since 2007.
  5. Less sea ice in the summer in the Chukchi Sea has meant a healthy prey base for polar bears because ringed seals feed primarily in the ice-free season.
  6. Polar bears have shown themselves to be adaptable to changing ice conditions in several regions.
  7. Southern Beaufort numbers have rebounded since the last survey count.
  8. Barents Sea numbers have probably increased since 2005 and have definitely not declined despite much less sea ice cover.
  9. There is no evidence that record-low summer sea ice in 2012 had a harmful effect on Southern Beaufort bear numbers.
  10. Other species are being negatively impacted by high polar bear numbers, especially nesting sea birds and ducks.
  11. Western Hudson Bay population numbers have been stable since 2004, despite what scientists are telling the media.
  12. Hudson Bay sea ice has not changed since about 1999: breakup dates and freeze-up dates are highly variable but the ice-free period was not any longer in 2015 than it was in 2004. However, this fall freeze-up is shaping up to be the earliest in decades.
  13. Problem bears in Churchill are not lean or starving.
  14. Churchill Manitoba had the most problem bears in 1983 and 2016, which were late freeze-up years, but many of the incidents in 2016 can be attributed to increased vigilance on the part of patrol officers after an attack in 2013.
  15. There have been only marginal sea ice declines during the feeding period in spring, when polar bears need sea ice the most.
  16. The is no evidence that subsistence hunting is affecting bear populations.
  17. Stressful research methods have been curtailed in much of Canada.
  18. There have been no reports of polar bear cannibalism since 2011.
  19. Polar bears appear unaffected by pollution: studies suggest only that harm is theoretically possible, not that it has happened.
  20. Polar bears have survived past warm periods, which is evidence they have the ability to survive future warm periods.


  • Polar bears are thriving: they are not currently threatened with extinction.
  • Tens of thousands of polar bears did not die as a result of more than a decade of low summer sea ice, as was predicted.
  • Polar bears don’t need sea ice in late summer/early fall as long as they are well-fed in the spring.

[full text below, pdf with footnotes and references here]

Continue reading

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.

Continue reading

W Hudson Bay polar bears won’t have an early breakup year, according to sea ice charts

There is still a huge swath of highly concentrated thick first year ice (>1.2m) over most of Hudson Bay this week (19 June 2017) and even in the NW quadrant (the closest proxy we have for Western Hudson Bay), the weekly graph shows levels are greater than 2016, when WHB bears came off the ice in good condition about mid-July. All of which indicates 2017 won’t be an early sea ice breakup year for WHB polar bears.

Hudson Bay weekly ice stage of development 2017 June 19

There is thick first year ice (>1.2m, dark green) in patches along the west coast in the north and south. Thick first year ice also extends into Hudson Strait and Baffin Bay, with some medium first year ice (0.7-1.2m thick, bright green) along the central and southern coasts of WHB.  Note the red triangles incorporated into the thick ice of Hudson Strait in the chart above: those are icebergs from Greenland and/or Baffin Island glaciers. A similar phenomenon has been noted this year off northern Newfoundland, where very thick glacier ice became mixed with thick first year pack ice and were compacted against the shore by storm winds to create patches of sea ice 5-8 m thick.

Compare the above to what the ice looked like last year at this time (2016 20 June, below). There is more open water in the east this year (where few WHB bears would likely venture anyway) but less open water around Churchill and Wapusk National Park to the south than there was in 2016:

Hudson Bay ice age weekly at 20 June 2016

We won’t know for several more weeks if most WHB bears will come ashore at about the same time as last year (early to mid-July) or whether they will be in as good condition as they were last year (because winter conditions may not have been similar).

But so far, sea ice conditions are not looking as dire as the weekly “departure from normal” chart (below, 19 June 2017) might suggest (all that “less than normal” red and pink, oh no!!):

Hudson Bay weekly departure from normal 2017 June 19 Continue reading