Monthly Archives: February 2017

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.

global-pb-population-size-graphic2_2017-feb-polarbearscience

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 2017a, b).

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.

Footnotes:

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 2017b) 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 2017a,b). 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%.

References

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]

Crockford, S.J. 2017a. 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/

Crockford, S.J. 2017b. Testing the hypothesis that a rapid and sustained decline of sea ice coverage to 5 mkm2 or less results in profound reduction of polar bear (Ursus maritimus) population size. PeerJ, submitted for peer review.

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

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).

sea-ice-at-19-feb-2017_vs-2006_nsidc-interactive

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Baffin Bay and Kane Basin polar bears not ‘declining’ concludes new report

The 2016 Scientific Working Group report on Baffin Bay and Kane Basin polar bears was released online without fanfare last week, confirming what local Inuit have been saying for years: contrary to the assertions of Polar Bear Specialist Group scientists, Baffin Bay and Kane Basin subpopulations have not been declining but are stable.

polar-bear-feeding_shutterstock_sm

Until recently, the Baffin Bay (BB) and Kane Basin (KB) polar bear subpopulations, that live between NW Greenland, and Baffin and Ellesmere Islands, were assessed with confidence by the IUCN Polar Bear Specialist Group (PBSG) to be declining due to suspected over-hunting (see 2016 Report, Ch. 1, pg. 4).

It turns out they were wrong.

map-baffinbay

New (2016) polar bear subpopulation estimates for BB and KB:

Baffin Bay 2,826 (95% CI = 2,059-3,593) at 2013

                  [vs. 1546 (95% CI = 690-2,402) expected 2004]

                  vs. 2,074 (95% CI = 1,553-2,595) in 1997

  Kane Basin357 (95% CI: 221 – 493) at 2013

                    vs. 164 (95% CI: 94 – 234) in 1997

[1997 figures from 2015 IUCN Red List estimates, from Supplement, pg. 8); 2004 “expected” figure for Baffin Bay from 2016 SWG report, Ch. 1, pg. 4]

In 2014, Environment Canada’s assessments were ‘data deficient’ for Kane Basin and ‘likely declining’ for Baffin Bay (see map below):
ec_polarbearstatus_and-trends-lg_2010-2014-mapscanada_oct-26-2014

However, the results of this new study (conducted 2011-2013) would likely make KB in the map above dark blue (‘stable’), and BB light blue (‘likely stable’), depending on how the new information is interpreted (given differences in methodology between the 1991-1997 and 2011-2013 counts). Note that a recent paper by Jordan York, Mitch Taylor and others (York et al. 2016) suggested this outcome for Baffin Bay was likely (i.e. ‘stable’) but thought that the status of Kane Basin would remain ‘declining.’

This new information leaves only the Southern Beaufort subpopulation (SB) in a ‘likely declining’ condition, but since that decline was due to thick spring ice conditions in 2004-2006 (Crockford 2017), it does not reflect a response to recent loss of summer sea ice. The new population estimates for Baffin Bay and Kane Basin also suggests that a revision needs to be made to the 2015 IUCN Red List assessment with respect to the global population estimate because polar bears are clearly more abundant in Baffin Bay and Kane Basin than previously thought.

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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

New paper updates lack of trend in W Hudson Bay breakup/freeze-up dates to 2015

A newly-published paper shows that there has been no trend in the time Western Hudson Bay polar bears spent onshore between 2001-2015 due to sea ice conditions at breakup or freeze-up (previously available to 2010 only), despite the marked decline of global sea ice since 2007.

castro-de-la-guardia-et-al-derocher-2017-fig-3-no-caption

Figure 3 from Castro de la Guardia (2017) showing freeze-up and breakup dates and ice-free days 1979-2015 for Western Hudson Bay. Figure with caption is copied below, with explanation of symbols.

Previously, a 2007 paper by Eric Regehr and colleagues for WHB bears up to 2004, which was used to support the US bid to list polar bears as ‘threatened’ with extinction, concluded that between 1984 and 2003, bears were spending 3 weeks long onshore than they did in the 1980s.

The big news from Castro de la Guardia (2017) is that polar bears spent longer onshore from 1979-2015 by … 3 weeks. That is, no change from the situation in 2004. Wow!

Note the population size of the entire WHB subpopulation has also not declined since 2004 and is currently estimated at about 1030, based on a 2011 aerial survey (Stapleton et al. 2014).

Thanks to Andrew Derocher for the heads-up tweet.

From the abstract (my bold):

We found that the ice-free period in this region lengthened by 3 ± 0.8 wk over the period 1979−2015. Polar bears migrated onshore 2 wk earlier and offshore 1 wk later in the period 2005−2015 than in 1980−1989.

Here is the region in question, illustrated by Fig. 1 from the paper:

castro-de-la-guardia-et-al-derocher-2017-fig-1a-locationThe significant information contained in this paper is breakup and freeze-up dates and length of the ice-free period data for 2010-2015, which has been unavailable until now. More excerpts and comments below, including Figure 3 with its caption. Continue reading

Svalbard polar bears thrive in part due to ringed seal pups in the spring pack ice

Few people know that Arctic ringed seals (Phoca hispida, aka Pusa hispida) give birth and breed in the offshore pack ice in the spring, as it is seldom mentioned by either seal or polar bear specialists.

While it is true that some ringed seals give birth in stable shorefast ice close to shore, many others give birth well offshore in thick pack ice – where polar bears also live and hunt in the spring but where few Arctic scientists ever venture – and the existence of pack ice breeding ringed seals is one of the reasons that polar bears are such a resilient species.

ringed-seal-in-snow-cave_b-kelly-wikipedia

Ringed seal pup in a snow cave, B. Kelly photo (Wikipedia).

As a consequence, despite fears expressed by Ian Stirling, low shorefast ice and associated snow around Svalbard this winter (and any time in the past) is not necessarily a hindrance to polar bear survival because there are ringed seal pups available out in the surrounding pack ice – where bearded seals also give birth.

Of course, ringed seals pups are also available to Svalbard polar bears in the shorefast ice in the Franz Josef Land archipelago to the east (see map below) but it is the pups born in the offshore pack ice that are of interest here. The existence of pack ice breeding ringed seals may be why Norwegian biologists do not currently monitor ringed seals in the Barents Sea, despite many years of poor ice conditions around Svalbard in spring – this simply is not a species of concern.

barents-sea-ice-2017-feb-6_nis

The fact that distinct ringed seal ecotypes (or habitat-specific morphotypes) exist in the Arctic – one that gives birth and breeds in shorefast ice and another that gives birth and breeds in offshore pack ice, perhaps driven by competition for limited shorefast ice habitat – is a phenomenon a colleague and I discussed in a peer-reviewed book chapter published several years ago. Have a look at the excerpt below and see what you think.

Save

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Listen to the evidence: polar bears are thriving in current sea ice habitat

Oddly, activist organization Polar Bears International recently updated their website and now suggest there is still time to save polar bears and sea ice – even though the IUCN Red List documented more polar bears alive in 2015 than at any time in the last 50 years, despite the recent decline of summer sea ice – and even more bizarrely, call for a public uprising.

2017-pbi-save-polar-bears-and-sea-ice

Polar Bears International (with three polar bear scientists on staff and other as active advisors) suggest that people who love polar bears should march the streets on Earth Day with scientists to demand (as concerned and engaged citizens) that world leaders take them seriously.

2017-peoples-climate-march-in-april-for-polar-bears-pbi-plea

Wow. I’ve been a career scientist for more than 40 years and I have to say, this is the oddest phenomenon I’ve encountered being advanced in the name of science. To me, it shows how disconnected these people are from what science is meant to be and what scientists are meant to do. Not just the polar bear scientists but the others like them that are behind this proposed march.

I recommend this blog post by Willis Eschenbach – an excerpt below.

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