IUCN PBSG insists the 2015 Barents Sea polar bear count was not an increase

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Similar to the spin on the 2013 Baffin Bay/Kane Basin polar bear population survey, the IUCN Polar Bear Specialist Group now insists the latest count of the Barents Sea subpopulation is not evidence of an increase in numbers since 2004, as the leader of the study announced in 2015.

This is Part 2 of the big surprises in the latest version of the polar bear status table published by the IUCN Polar Bear Specialist Group (PBSG) on 30 March 2017. See last post here regarding the PBSG population size estimates that no longer concur with the 2015 Red List assessment, including the global total — even though PBSG members wrote the report (Wiig et al. 2015, and its Supplement).

Here I want to focus on the results of subpopulation surveys that were made public after the 2015 Red List assessment was published, particularly the Barents Sea estimate.

While the 2013 Baffin Bay and Kane Basin estimates (SWG 2016) have been added to the new PBSG table, any suggestion that these might indicate population increases are strong discounted. Similarly, contrary to initial reports by the principal investigators of the survey, the PBSG insist that the Barents Sea population has not actually increased since 2004, which you may or many not find convincing.

Some of the recent prolonged PBSG discussion about the polar bear status table at their last meeting in 2016 almost certainly involved what to do about the Barents Sea survey conducted in August 2015 by Jon Aars and colleagues at the Norwegian Polar Institute (Svalbard area only, see photo below).

As you’ll recall, Aars issued a press release (pdf here) and told the world his results: that most bears were in excellent condition (“many looked like pigs“) and that they’d recorded a 42% increase in the number of bears counted, which they interpreted as a real and significant increase — and not particularly surprising:

“A rise in the population does not come as a big surprise, as population numbers previously have been low due to the fact that these bears were hunted until 40 years ago, Dr. Aars added.”

But here is what local reporters (NTB: News in English from Norway, published 23 December 2015), who were able to contact him for an interview (pdf here), had to say:

“Researchers from Norsk Polarinstitutt in Tromsø have conducted their first census of sorts since 2004 regarding the polar bear population on Svalbard and in the Norwegian portions of the Barents Sea. “The population has increased,” project leader Jon Aars of the polar institute told NTB. “The Norwegian polar bear population is now calculated to include around 975 bears, compared to 685 11 years ago.”

Aars stressed that there’s a degree of uncertainty in the numbers, but he thinks the researchers have the necessary basis to claim that there’s been an increase in the total.

He also said the polar bears spotted and counted were in “good shape.” He said the ice “came early in the fall of 2014 and lasted a long time.” That means a lot for the bears, he noted.

Ice conditions in the Barents have been poor in most years since 2000, and researchers have been extremely worried about the state of the polar bear population. “It’s positive to see that the polar bears have managed well, under conditions that have been worse for several years,” Aars told NTB.” [my emphasis]

This is how I described the current size of the Barents Sea subpopulation (Crockford 2017), noting that such an increase was expected by Norwegian researchers:

“…a recent update to the Wiig et al. (2015) data for BS is now available: according to a press release issued by the government entity that conducted the survey, in 2015 the Svalbard portion of the BS increased by 42% (from 685 to 975, an increase of 290) since a similar count in 2004 (Norwegian Polar Institute 2015), and apparently anticipated despite poor sea ice conditions since 2004 (Fauchald et al. 2014). Applied to the entire region (using the estimate derived by Aars et al. (2009) of 2650) gives a 2015 estimate of about 3749, an increase of 1109. This estimate fits well with the comment by Aars et al. (2009) that in 2004 there were “about three times” (actually 2.87) as many bears in the Russian sector than in Svalbard and thus, using the Svalbard figure of 975 generates an estimate of about 3773 for the entire region.”

While my calculations may have generated a slightly inflated estimate, it is not an implausible total under the circumstances. I used this number not to insist that a significant increase had taken place but that a significant decline had not occurred.

Below is what the 2017 PBSG assessment says about the Barents Sea survey. We’ll probably never know how much pressure was applied to the Norwegians to make their study results conform to the objectives of the PBSG, which now dismiss the 42% increase in Svalbard numbers as within the confidence limits of the previous estimate (Aars et al. 2009) of 2,650 (1900-3600):

“A new survey in the Norwegian extent of BS was conducted in August 2015. The ice edge was located beyond an ice-free gap north of the Svalbard Archipelago. The number of bears encountered in Svalbard indicates that there is a local stock of ~200-300 bears (preliminary results), which did not differ much from the number detected in 2004.

The results (J. Aars et al., in prep.) also indicate, in accordance with the results from 2004, that more bears are off-shore in the pack ice in autumn. The total estimated for Norwegian Arctic was just under 1000 bears, considerably higher than the total for the Norwegian side in 2004, but with a confidence interval overlapping with the earlier estimate.

During the new survey, the distribution of bears was clumped along the ice edge with most bears close to the Russian border, but access to the Russian portion of BS, for aerial survey, was not permitted. Because of the overlapping confidence intervals, it cannot be concluded that the BS subpopulation has grown.

It is believed that excess hunting in the area before 1973 led to a population size far below the carrying capacity. Consequently, it could be that the current population size is still lower because of an ongoing decline in, carrying capacity. Thus, it is unclear what the trajectory of the subpopulation will be in near future; we do expect that habitat loss will continue. There have not been any dramatic time trends in reproduction or condition parameters in BS, although poor ice years seem to influence these parameters.”

What if there had been a 42% decline in numbers — would the same contortions of interpretation have been applied to dismiss its significance? I wonder.

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.

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 2 March 2017. Doi: 10.7287/peerj.preprints.2737v3 Open access. http://ift.tt/2ozOors

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://ift.tt/2mdVkKt

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://ift.tt/2lTHatD9

Wiig, Ø., Amstrup, S., Atwood, T., Laidre, K., Lunn, N., Obbard, M., Regehr, E. & Thiemann, G. 2015. Ursus maritimus. The IUCN Red List of Threatened Species 2015: e.T22823A14871490. Published online here; PDF copy of report here;
PDF of supplement here.

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May 1, 2017 at 05:38PM

IUCN Specialist Group now rejects polar bear numbers it used for 2015 IUCN Red List review

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Is there a mutiny in the works between the IUCN Red List and the IUCN Polar Bear Specialist Group (PBSG) over polar bear population estimates or has there simply been a breach of ethics? What else explains the fact that some of the subpopulation estimates used by the PBSG to support the status of ‘vulnerable’ for the IUCN Red List in 2015 are unacceptable to them in 2017? And why are the PBSG refusing to embrace the Red List global estimate of 22,000-31,000?

The latest version of the IUCN PBSG status table was posted online 30 March 2017 without fanfare or even a note on their home page. It seems the result came from much discussion at their official meeting last summer (June 2016) that they say continued into early March 2017.

PBGS members voted to reject four subpopulation estimates used in the 2015 Red List polar bear status review  — even though the inclusion of those numbers was required in order for the Red List status of ‘vulnerable’ to be upheld. The group has also chosen not to update their global population page with the Red List estimate of 22,000-31,000.

And surprise, surprise — now that only one subpopulation out of nineteen worldwide has shown a recent decline, the PBSG have removed the “trend” columns from their summary table for subpopulations.

Welcome to conservation ‘science’ practiced by IUCN polar bear specialists.

Regular readers may recall that the quality control folks at the Red List insisted in 2014 that a status assessment of ‘vulnerable’ based on future risks generated by predictive computer models could only be used if estimates were provided for all subpopulations (as was stated clearly in the minutes of one of the PBSG meetings posted online, read marked excerpt here).

Below find the pertinent quotes regarding concerns raised by the Chairman of the IUCN Standards and Petitions Committee, where the “Bayesian Network (BN) approach” refers to the method used by the US Geological Survey (Amstrup et al. 2007) to support an Endangered Species Act classification of ‘threatened’ for polar bears in 2008 (my bold):

“Four shortcomings of the Bayesian Network (BN) approach (from the standpoint of the work of Amstrup et al. and the Red List requirements were noted. …It was agreed that the Red List Assessment has quantitative requirements which would not be met by current renditions of the BN model.”

…

“We also need reasonable estimates of the size of all subpopulations; we cannot simply say, for example, that for subpopulations where are [sic] estimates are currently poor that in the future these will be 20% lower.” [Pg. 15-16]

Accordingly, the PBSG members who wrote the Red List assessment report included “reasonable” estimates for the three subpopulations that have never been surveyed (Chukchi Sea, East Greenland, and Laptev Sea) plus a survey result they didn’t especially like for the Kara Sea — and got their Red List determination of ‘vulnerable’ accepted.

However, now that the PBSG have the status result they wanted from the Red List assessment, they have rejected all four of those “reasonable” numbers, including the 2013 Kara Sea estimate that was based on a legitimate survey (described here).

This is not the first time that individual PBSG members have used subpopulation estimates that the group formally decided were ‘unacceptable’ when it suited them to do so. For example, Karyn Rode and colleagues (2014:78) used the Chukchi Sea estimate of ‘2000’ for a comparison of Beaufort Sea bears and sea ice conditions, even though the PGSG had listed the Chukchi Sea population size as “unknown” in 2009 (Obbard et al. 2010).

It follows from the above rejection of these four subpopulation estimates that the PBSG also appears to have rejected the 2015 Red List global population estimate (of course, because the numbers would no longer add up).

A full month after all of the other pages were updated, the “global population size” page remains as it was in July 2014 (after the chairman emailed me to say their estimates were a “qualified guess given to satisfy public demand“). There is still no mention (on this page or anywhere else on the website) of the 2015 IUCN Red List assessment estimate of 22,000-31,000 co-authored by PBSG members Wiig, Amstrup, Atwood, Laidre, Lunn, Obbard, Regehr, and Thiemann (Wiig et al. 2015; see the Supplement, Table 3, for the subpopulation estimates used).

Equally outrageous is that since the Southern Beaufort Sea subpopulation (out of all 19 worldwide) is the only one to have recently documented a decline (Crockford 2017), the new status table no longer contains an assessment of trend (see snapshot of upper half below, full pdf here). Most other subpopulation are stable or increasing, including Baffin Bay and Kane Basin (in 2014, Baffin Bay was the only other population thought to be declining), although several are still ‘data deficient’.

Compare the above to the 2014 table snapshot below with the trend column entries marked prominently (full pdf here) and an option to download the status table.

[Note that the “status map” page (updated 27 March 2017) does contain trend information for a few select subpopulations]

You will only find the 2014 table here, as there is no archive function on the PBSG status table page — previous versions simply disappear. This means there has been no archive of polar bear status tables since the 2009 meeting report (minutes of meetings since then have been published but those reports do not include the status assessment tables and descriptions as previous reports have done).

The hubris on display here is simply mind-boggling.

The PBSG seems to have planned to get the 2015 Red List assessment of ‘vulnerable’ by any means necessary, even if it meant using subpopulation estimates the group felt were too inaccurate to use for any other purpose.

I’ll have more to say about the PBSG treatment of the Barents Sea survey results in my next post (call it PBSG 2017 update, part 2).

References

Amstrup, S.C., Marcot, B.G. & Douglas, D.C. 2007. Forecasting the rangewide status of polar bears at selected times in the 21st century. US Geological Survey. Reston, Virginia. pdf here.

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. http://ift.tt/2ozOors

Obbard, M.E., Theimann, G.W., Peacock, E. and DeBryn, T.D. (eds.) 2010. Polar Bears: Proceedings of the 15th meeting of the Polar Bear Specialists Group IUCN/SSC, 29 June-3 July, 2009, Copenhagen, Denmark. Gland, Switzerland and Cambridge UK, IUCN.

Rode, K.D., Regehr, E.V., Douglas, D., Durner, G., Derocher, A.E., Thiemann, G.W., and Budge, S. 2014. Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations. Global Change Biology 20(1):76-88. http://ift.tt/1EgcV71 

Wiig, Ø., Amstrup, S., Atwood, T., Laidre, K., Lunn, N., Obbard, M., Regehr, E. & Thiemann, G. 2015. Ursus maritimus. The IUCN Red List of Threatened Species 2015: e.T22823A14871490. Published online here; PDF copy of report here;
PDF of supplement here.

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May 1, 2017 at 05:13PM

Antarctic Peninsula Ice More Stable Than Thought

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Glacier flow at the southern Antarctic Peninsula has increased since the 1990s, but a new study has found the change to be only a third of what was recently reported. The new research calls into question recent claims of much more dramatic ice loss.

An international team of researchers, led by the UK Centre for Polar Observation and Modelling at the University of Leeds, are the first to map the change in ice speed. The team collated measurements recorded by five different satellites to track changes in the speed of more than 30 glaciers since 1992.

The findings, published today in Geophysical Research Letters, represent the first detailed assessment of changing glacier flow in Western Palmer Land — the southwestern corner of the Antarctic Peninsula.

View from the British Antarctic Survey (BAS) Rothera research station, on Alexander Island at the Antarctic Peninsula

The new Leeds led research calls into question a recent study from the University of Bristol that reported 45 cubic kilometres per year increase in ice loss from the sector. The Leeds research found the increase to be three times smaller.

Lead author Dr Anna Hogg, from the Leeds’ School of Earth and Environment, said: “Dramatic changes have been reported in this part of Antarctica, so we took a closer look at how its glaciers have evolved using 25 years of satellite measurements dating back to the early 1990s.”

The researchers found that between 1992 and 2016, the flow of most of the region’s glaciers increased by between 20 and 30 centimetres per day, equating to an average 13% speedup across the glaciers of Western Palmer Land as a whole.

These measurements provide the first direct evidence that Western Palmer Land is losing ice due to increased glacier flow — a process known as dynamical imbalance.

The team also combined their satellite observations with an ice flow model using data assimilation to fill in gaps where the satellites were unable to produce measurements. This allowed the complete pattern of ice flow to be mapped, revealing that the regions glaciers are now pouring an additional 15 cubic kilometres of ice into the oceans each year compared to the 1990s.

The earlier study reported that the region was losing three times this amount of ice, based on measurements of glacier thinning and mass loss determined from other satellite measurements. The Leeds study casts doubt on that interpretation, because the degree of glacier speedup is far too small.

Study co-author Professor Andrew Shepherd, from Leeds’ School of Earth and Environment, explained: “Although Western Palmer Land holds a lot of ice – enough to raise global sea levels by 20 centimetres – its glaciers can’t be responsible for a major contribution to sea level rise, because their speed has barely changed over the past 25 years. It’s possible that it has snowed less in this part of Antarctica in recent years – that would also cause the glaciers to thin and lose mass, but it’s a not a signal of dynamical imbalance.”

The greatest speedup in flow was observed at glaciers that were grounded at depths more than 300 m below the ocean surface.

Dr Hogg said: “We looked at water temperatures in front of the glaciers which have sped up the most, and we found that they flow through deep bedrock channels into the warmest layer of the ocean. This circumpolar deep water, which is relatively warm and salty compared to other parts of the Southern Ocean, has warmed and shoaled in recent decades, and can melt ice at the base of glaciers which reduces friction and allows them to flow more freely.

With much of Western Palmer Land’s ice mass lying well below sea level it is important to monitor how remote areas such as this, are responding to climate change. Satellites are the perfect tool to do this.

Pierre Potin, ESA’s Manager of the Copernicus Sentinel-1 Mission which was used in the study, said: “We will continue to use Sentinel-1’s all weather, day-night imaging capability to extend the long term climate data record from European satellites.”

Hogg, A. E., et al. (2017), Increased ice flow in Western Palmer Land linked to ocean melting, Geophys. Res. Lett., 44, (DOI:10.1002/2016GL072110) 

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May 1, 2017 at 05:07PM

Oops… Antarctic Peninsula ice more stable than thought

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May 1, 2017 at 05:03PM