Tag Archives: Polar Bear Specialist Group

Amstrup knows his polar bear predictions are flawed – but continues to promote them

The largest conservation organization in the world says that predictive models developed by polar bear biologist Steven Amstrup are utterly unsuitable for scientifically estimating future populations. Earlier this year, mathematical modeling experts  at the International Union for the Conservation of Nature, who maintain the Red List of Threatened Species, made it clear that Amstrup’s models (used in 2008 to convince the US Fish and Wildlife Service to list polar bears as ‘threatened’ due to predicted global warming) do not meet IUCN standards.

I’d say this makes Amstrup’s polar bear projections (Amstrup et al. 2008, 2010) no more scientifically useful than a crystal ball prophesy, but you wouldn’t know it by his recent actions — or the silence of his fellows.

crystal ball_3c

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Polar Bears International responds to “The Politics of Polar Bears”

Well, sort of — what they did was provide a logical fallacy reply to an almost incoherent comment by a PBI Facebook supporter who had watched the documentary and complained of bias (such a predictable response).

See what you think, screen-cap below (taken September 3, 2014 at about 2PM Pacific Time.
[UPDATE added September 4, 2014 at 8:30PM Pacific, see below]

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Reflections on my House of Lords lecture: Healthy polar bears, less than healthy science

Here is an excerpt of an essay I wrote reflecting on the recent (11 June 2014) lecture I gave at the House of Lords in London (“Healthy polar bears, less than healthy science”). The Global Warming Policy Foundation (GWPF) has just published that 14 page essay in its entirety as its 10th such report but you can get a taste of it here.


My piece addressed the following issues that I talked about in the lecture or which came up afterwards during the question period and discussions later:

•  On what do you base your assertion that polar bear populations are “healthy”?
•  Are the media — or polar bear scientists — to blame for hyping the “polar bears are dying” meme?
•  How significant was the recent dismissal of a petition to force Canada into listing polar bears as ‘threatened with extinction’?
•  What do the recent actions of the Polar Bear Specialist Group say about their commitment to good science?
•  Is my blog helping to “self-correct” the science on polar bears?

The highlighted point is copied in full below. See the full essay here.
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Polar Bear Specialist Group just had another secret meeting

Well, well, well — it looks the Polar Bear Specialist Group (PBSG) just had itself another secret meeting with some extra special guests.

pbsg logoPolar bear scientists and PBSG-approved activists got together a few weeks ago (June 9-13), with no notice beforehand, to continue discussions how (sic) to solve issues of future capacity.”

This was their “second intersessional members-only meeting in a row” (the first one was in October 2012), but they still haven’t had their regular, now long-overdue, “working meeting.” [they had the last one in 2009].

I came upon a notice about this meeting on the PBSG website, which apparently went up June 26, while looking for something else. There has been nothing about it in the media that I’ve seen.

And guess who were “invited specialists” at this meeting of “members-only,” called “to discuss internal matters crucial for the future functioning and capacity of the group”?

Three “climate scientists“!

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Southern Beaufort polar bear ‘decline’ & reduced cub survival touted in 2008 was invalid, PBSG now admits

It is now clear that the phenomenon of bears moving across Southern Beaufort Seapbsg logo subpopulation boundaries compromised the US decision to list polar bears as ‘threatened’ and the IUCN Polar Bear Specialist Group (PBSG) knows that was the case.

As I pointed out last week, the PBSG has admitted in their 2013 status table update (pdf here) that bears move around so much between the Chukchi Sea (CS), the Southern Beaufort (SB), and the Northern Beaufort (NB) subpopulations that major changes in the boundaries of the SB subpopulation are necessary (see Fig. 1 below).

Figure 1. From the paper by Amstrup and colleagues (2005) describing the effect that movement of bears across subpopulation boundaries has on setting harvest quotas – and population estimates. Southern Beaufort boundary is solid red, Chukchi Sea is dashed yellow and Northern Beaufort is dotted light blue. “Point Barrow” is Barrow, AK (well inside the SB boundary). Click to enlarge.

Figure 1. From the paper by Amstrup and colleagues (2005) describing the effect that movement of bears across subpopulation boundaries has on setting harvest quotas and population estimates. Southern Beaufort (SB) boundary is solid red, Chukchi Sea (CS) is dashed yellow and Northern Beaufort (NB) is dotted light blue. “Point Barrow” is Barrow, AK (well inside the SB boundary). Click to enlarge.

Well, that’s not really news — changes to the SB boundaries were promised by the PBSG back in 2009 (Obbard et al. 2010), based on research by Steven Amstrup and colleagues published in 2001 and 2005. But now, in an astonishing admission, the PBSG have acknowledged that the last population survey for the SB (Regehr, Amstrup and Stirling, 2006), which appeared to register a decline in population size and reduced cub survival over time, did not take known movements of bears into account as it should have done.

In other words, that 2006 study almost certainly did not indicate bears dying due to reduced summer sea ice in the SB, as biologists said at the time — and which they presented as evidence that polar bears should be listed by the ESA as ‘threatened’ — but reflected capture of bears that were never part of the SB subpopulation and so moved out of the region.

As the PBSG said about the 2006 estimate:

“…it is important to note that there is the potential for un-modeled spatial heterogeneity in mark-recapture sampling that could bias survival and abundance estimates.” [my emphasis]

Spatial heterogeneity” means that the sampled bears could have come from more than one population, a possibility which violates a critical requirement of the statistics used to generate the population and survival estimates. “Un-modeled” means that the ‘movement of bears’ problem was not factored into the mathematical models that generated the 2006 population size and survival estimates as it should have been.

Ecologist Jim Steele pointed some of this out in his book and his guest post last year, so it’s not news that this was done.

What’s shocking is that the PBSG have now admitted that the ‘movement of bears’ issue essentially invalidates the 2006 population estimate and the much-touted ‘reduced survival of cubs.’ The reduced survival of cubs data from that SB study was a critical component of the argument that US bears were already being negatively impacted by global warming and thus, should be listed as ‘threatened’ under the ESA (US Fish & Wildlife Service 2008).

Since the population decline and reduced survival is now acknowledged to be unfounded — and perhaps deliberately so — I ask you this: will a new SB survey — soon to be released by the same lead author (Eric Regehr) — undo the broken trust in US and PBSG polar bear biologists? Continue reading

2013 PBSG polar bear status table information in one document

As I pointed out on Valentine’s Day, the IUCN Polar Bear Specialist Group (PBSG) has released a revised population estimate for polar bears of 18,349 (range 13,071-24,238), based on a new status table posted February 14, 2014.

PBSG status-table-2013_Feb 14 2014_intro

In that February 14th post, I also pointed out that as for the 2005 and 2009/2010 status tables, the PBSG did not add up the columns and give the totals — you had to do that yourself, which is how I got the numbers above (last week, I made a couple of graphs that show changes over time in their status table estimates). Oddly enough, there is now no mention of an official global polar bear estimate anywhere on the PBSG website.

In addition — and the point of this post — is that to see the details of how and why the PBSG biologists arrived at the population estimates and the status assessments they present (with references), you have to click on the hyperlinked title of each separate subpopulation in the table. While they made a one-page black and white summary of the online colour table available as a pdf (linked at the bottom of the page), they did not make the assessment details from the status table available in pdf format.

So I did it myself, via copy/paste into a Word document that I converted to a searchable pdf, without editorial comment except that I included the totals given above and noted a few glaringly obvious omissions (see below). It took me all of 30 minutes.

I offer it here for more effective scrutiny, convenient reference and archival purposes — because the way it stands now, the online table could disappear tomorrow without any hard-copy evidence of the information hyperlinked within it.

UPDATE February 26, 2014 I checked the PBSG website this morning and the omissions I noted below that were present a few days ago have been fixed. I did not receive a reply to my email notification of the issue. An updated pdf is now available.

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Graphing polar bear population estimates over time

I’ve already commented on the 2013 update of polar bear population status released by the IUCN Polar Bear Specialist Group (PBSG).

However, I thought it might be interesting to graph the changes in global population estimates over time (from 1981-2013) — not just the actual estimates from PBSG status tables (with their min/max error ranges) but those totals plus the so-called “inaccurate” estimates that the PBSG have dropped from their accounts in recent (2005-2013) assessments: Chukchi Sea, East Greenland, Queen Elizabeth Islands (now known as the “Arctic Basin”), and Laptev Sea.

In 2001, those “inaccurate” estimates contributed 5,000-5,400 bears to the global total, but now they’re gone — no bears from those regions contribute to the official totals listed on recent PBSG status tables.

Adding those dropped estimates back into the global totals makes it possible to generate a graph in which the global estimates are truly comparable over time.

To see how the dropped estimates influenced the perception of population change over time, I’ve also graphed the estimates given by the PBSG in their status tables. I’ve combined the two into one image (Fig. 1, click to enlarge) to make comparison easy.

UPDATE 5 December 2014: Links to more recent posts relevant to this issue added below.
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