Category Archives: Summary

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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Exposing the failed polar bear scare to a an enthusiastic and influential audience

I’ve just returned from a few days in Washington DC, where I presented the details on the global warming icon that refused to die as modeled (see my slide #12 below) to an enthusiastic and influential audience at The Heartland Institute‘s 12th International Climate Change Conference (ICCC-12).

Crockford 2017_Slide 12 screencap

Polar bear science got some long overdue scrutiny by a large number of people at this meeting. Not unexpectedly, a good many folks were surprised and outraged to learn how the polar bear/sea ice situation has actually unfolded compared to the predicted outcome and on-going media hype.

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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 (and updated with new data).

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.

Announcing the release of Polar Bears: Outstanding Survivors of Climate Change

It’s here! The book that explains, in just enough detail, why polar bears are thriving despite the gloomy prognostications of the data collectors and future survivor modelers.


Here is all the science you need to know to understand contemporary polar bear issues of sea ice loss and species extinction. It contains the most up-to-date information available in an easy to digest format, with references to back it up. Continue reading

As polar bear populations fail to decline with sea ice, message of doom intensifies

If 10 years of summer sea ice levels expected to kill 2/3 of the world’s polar bears by 2050 hasn’t had an impact, why would anyone expect a bit less summer ice will do the job?


The more the polar bears fail to die in droves, the shriller the message from activist polar bear researchers – via willing media megaphones – that the great death of the bears will soon be upon us, just you wait and see!

Some big media guns were out this past week spreading the prophesy of doom fed to them by the polar bear researchers most committed to the “threatened with extinction” narrative: The New York Times, The Atlantic, The Guardian. The desperation is becoming palpable as the public catches on to their epic failure.

In 2007, the sea ice dropped to a level the experts said wouldn’t be reached until mid-century, and since then, it has remained at that low level (about 3-5mkm2, give or take some measuring error). And in 2007, US Geological Survey (USGS) biologists said with absolute confidence that when sea ice levels reached that point, 2/3 of the world’s polar bears would be gone.

No bears at all would remain, they said, in Western Hudson Bay (the Churchill bears), Southern Hudson Bay, Foxe Basin, Davis Strait, Baffin Bay, Southern Beaufort, Chukchi Sea, Barents Sea, Kara Sea, and the Laptev Sea:  ten out of 19 subpopulations would be extirpated if sea ice levels in most years dropped to the summer lows in the 3-5 mkm2 range.

On the basis of that prediction, polar bears were declared ‘threatened’ with extinction by the US Fish & Wildlife Service (USFWS) under the Endangered Species Act (ESA).

But nothing of the kind happened. There are still lots of polar bears – and not even struggling-to-survive bears but lots of fat healthy bears everywhere across the Arctic, in what were considered by USGS biologists to be the most vulnerable regions of all: Western Hudson Bay (i.e., Churchill), Chukchi Sea and Southern Beaufort (Alaska) and the Barents Sea (Norway).

This is the truth the world needs to hear: the experts were wrong. Polar bears have not been driven to the brink of extinction by climate change, they are thriving. This is the message of each of my two new books (one of which is appropriate for kids of all ages, see the sidebar).

In turns out that polar bears are much more resilient to changing levels of sea ice than data collectors assume and the proof is in the current healthy populations everywhere. Continue reading

Coming soon: the polar bear science books you’ve been requesting

It’s just past the first anniversary of the publication of my science-based novel, EATEN, so satisfied readers may be pleased to learn that I have a pair of polar bear science books set to be released.

Finally – books for adults and children that present the facts about polar bears without spin and fear-mongering about model-predicted futures: reference books that include the most up-to-date information that show polar bears have the innate ability to adapt quickly to changes in sea ice.

Barring major revisions, the covers will look like this:


One is a fully-referenced book for adults and high school kids called Polar Bears: Outstanding Survivors of Climate Change.

The other is a fabulous companion or stand-alone summary volume (ages 7 and up), called Polar Bear Facts and Myths: A Science Summary for all Ages..

Both books are full-color and relatively short. With luck, they should be available next week, so stay tuned for details. Each will sell for well under US$20 (exact prices unknown).

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History of anxiety over sea ice gets a video

A brief historical perspective on the failed predictions that have plagued scientific understanding of Arctic sea ice changes – predictions embraced wholeheartedly by polar bear specialists and conservation experts. It’s worth a watch.

Transcript here from the Global Warming Policy Foundation.