Good news about polar bears, thriving as the arctic warms!

Summary: An oddity of the press coverage of our changing climate is that the news is always bad. Here is an example of unreported good news, about polar bears not just avoiding extinction — but thriving (less hunting by their #1 enemy has helped). There has been much bad news this year; let’s enjoy the rare good news.

If experts had been right about sea ice,
there would be no polar bears in Churchill

By Susan Crockford, Polar Bear Science. Reposted with her generous permission.

The simple fact is that if polar bear experts had been right about the threat to polar bears from the loss of summer sea ice in the Arctic, there would be no polar bears in Churchill this fall. No bears for tourists to photograph, none for biologists to study, and certainly none for the BBC to film for an upcoming three-part TV special called “Arctic Live”.

The low-ice future that biologists said would doom polar bears to extinction by 2050 has already happened in 8 out of the last 10 years. The sea ice future has arrived. Polar bears have experienced those supposedly deadly low-ice summers for almost a decade but the global population did not drop by 2/3 as predicted and not a single one of the ten subpopulations predicted to be extirpated under those conditions has been wiped out.

How much more wrong can you be than that? Will the BBC mention this conundrum in their show? Will the polar bear experts they consult share this fact with viewers? We’ll all have to watch and see (show times and summaries of each program, 1-3 November.) Here are background facts that might enhance your viewing experience.

We’ve already had the sea ice future

“Dominant outcomes of the BN model were for extinction [extirpation] of polar bear populations in the Seasonal Ice and Polar Basin Divergent Ecoregions by 45 years from present [2050]… Our modeling suggests that realization of the sea ice future which is currently projected, would mean loss of ≈ 2/3 of the world’s current polar bear population by mid-century.” (Amstrup 2007) [My emphasis.]

Assuming low summer sea ice like we’ve had for 8 out of the last 10 years, total eradication of Western Hudson Bay polar bears – as well as extirpation of bears in nine other subpopulations – is what USGS polar bear researchers predicted when they filed their reports in 2007 to support listing polar bears as ‘threatened’ under the US Endangered Species Act (Amstrup 2007; Durner 2007). Eradication of those ten subpopulations (plus declines in others), the experts said, would cause the global population to decline by 67%.

In 2007, USGS experts predicted that all of the bears in the green and purple regions would be wiped out if sea ice declined to low extents by 2050. However, the ice declined faster than expected – we’ve had that dreaded sea ice future since 2007, and polar bears thrived. Not a single one of those 10 subpopulations has disappeared. In other words, predicted devastation of polar bear populations did not require summer sea ice to disappear completely – just to drop to levels like we’ve seen since 2007.

Yet, almost a decade of polar-bear-destroying sea ice levels did virtually none of the damage predicted to occur – fat polar bears still come ashore in Western Hudson Bay and migrate through Churchill waiting for ice to form, and not a single subpopulation (let alone ten) has been wiped out (Wiig 2015).

Global polar bear numbers have not declined at all, let alone a decline of 67% – in fact, the latest estimate of 22,000-31,000 polar bears worldwide (IUCN Red List, 2015) is the highest it’s ever been.

…This situation is not news to the polar bear experts that predicted a gloomy future for the bears back in 2007. Amstrup 2008 (a peer-reviewed version of the USGS report Amstrup 2007 used to support the ESA listing of ‘threatened’) states “…five of the models we used in our analyses project more perennial sea ice [i.e. what’s left at the Sept. minimum] at mid-century than was observed in 2007”. …Note that the National Snow & Ice Data Center says that 2016 reached the same low as 2007. More on this here.

Map of four polar bear ecoregions defined by grouping recognized subpopulations which share seasonal patterns of ice motion and distribution. From Amstrup 2010. Click to enlarge.

Churchill bears in fine shape this year

As I pointed out more than three months ago, the word from bear guides north of Churchill in late July 2016 was that “Bear numbers are up spectacularly this year and all are looking very fat and healthy, perhaps much to the chagrin of climate change ‘experts’.” The first report from the Churchill Polar Bear Alert program (week of 11-17 July 2016) had this to say: “Bears are off the sea ice and on land. They are looking well fed and in great shape.”

See these posts for more information

Here are links to some pertinent posts that might answer your questions after watching the show. All are based on peer-reviewed literature and cite the references quoted, usually with links to where you can find the papers themselves. If you see one you’d like to read but cannot find it, send me a message and I will see that you get it.

(1) Western Hudson Bay polar bear numbers are stable, no trend in ice breakup or freeze-up. This needs saying again: the latest study on Western Hudson Bay polar bears reveal the population has been stable since 2004 and there has been no significant trend in either breakup or freeze-up dates since 2001.

(2) Recent studies show Sept ice of 3 to 5 mkm2 did not kill polar bears off as predicted. Recall that in 2006, the IUCN Polar Bear Specialist Group based their conservation status of ‘vulnerable’ (likely to become threatened within the next 45 years due to reduced habitat) on the predictions of sea ice specialists (see 2008 update here). Sea ice experts in 2005 predicted such low summer sea ice extents as polar bears have endured since 2007 (3.0 – 5.0 mkm2) would not happen until 2040-2070, at which time PBSG biologists said that >30% of the world’s bears would be gone.

(3) IUCN Red List says global polar bear population is 22,000 – 31,000 (26,000 mean). If global numbers do decline over the next 35 years, it will be from a high point not previously acknowledged by the IUCN Polar Bear Specialist Group (PBSG).

(4) Condition of S Hudson Bay polar bears varies with freeze-up only says new study. Despite the fact that the polar bears of Southern Hudson Bay (SHB) live further south year round than any others, a recent study found their average body weight has declined relatively little since the 1980s. There has been no decline in the size of the population over that time either.

References

“Forecasting the rangewide status of polar bears at selected times in the 21st century” by S.C. Amstrup et al, US Geological Survey (2007). PDF here.
“A Bayesian network modeling approach to forecasting the 21^st century worldwide status of polar bears” by S.C. Amstrup et al in Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications (2010).
“Polar Bears and climate change: Certainties, uncertainties, and hope in a warming world” by S. C. Amstrup in Gyrfalcons and Ptarmigan in a Changing World (2011).
“Predicting 21st-century polar bear habitat distribution from global climate models” by G.M. Durner et al, US Geological Survey (2007).
“Predicting 21st-century polar bear habitat distribution from global climate models” by G.M. Durner et al, Ecological Monographs, February 2009.
The IUCN Red List of Threatened Species 2015: Ursus maritimus. Classified at vulnerable.

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About counting polar bears: be skeptical

Polar bears have recovered, but probably not the 3x or 5x some claim. Peter Dykstra explains in the SEJournal (by the Society of Environmental Journalists), Summer 2008.

“The Soviets, despite their horrendous environmental legacy on many issues, banned most polar bear hunting in 1956. Canada and the U.S. followed suit in the early 1970s — with limited exceptions for some native hunting, and permitted, high-priced trophy hunts. And a curtailment of some commercial seal hunting has sparked a seal population explosion — angering fishermen, but providing populations in eastern Canada and Greenland with plenty of polar bear chow, leading in turn to localized polar bear population growth in spite of the ice decline.”

Dr. Steven C. Amstrup, chief scientist with Polar Bears International and USGS polar bear project leader for 30 years, explains why we know so little about polar bears’ history.

“One Russian extrapolation presented in 1956 suggested a number of 5,000 to 8,000, but that figure was never accepted by scientists. The fact is that in the 1960s we had no idea how many polar bears there were. Even now, about half of our population estimates are only educated guesses. Back then, the best we had over most of the polar bear’s range were uneducated guesses. Polar bear science has come a long way since then.

“We do know (and I have published papers on this) that some polar bear populations grew after quotas were imposed in Canada, aerial hunting ceased in Alaska, and trapping and hunting were banned in Svalbard. All of these events occurred in the late 60s or early 70s, and we know some populations responded — as you would expect. Some populations were not being hunted back then (or were hunted very little) and those were probably unaffected by these three actions.” {Source here.}

About the author

Susan Crockford is a zoologist with more than 35 years experience, including published work on the Holocene history of Arctic animals. She is an adjunct professor at the University of Victoria, British Columbia (a “non-remunerated professional zooarcheologist associate”) and co-owner of a private consulting company, Pacific Identifications Inc. See her publications here. and her website Polar Bear Science.

She has also written a novel, Eaten — a polar bear attack thriller.