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.
Since the mid-June 2014 meeting of the IUCN Polar Bear Specialist Group (discussed here and here; pdf excerpt here) – when the IUCN criticisms of Steven Amstrup’s models were made public – Amstrup (an active PBSG member) has continued to actively promote his flawed predictions. What’s more, none of his colleagues, or the model reviewers, have said a public word.
Here are some examples of PBSG member Steven Amstrup’s recent interviews and/or opinion pieces where he promotes his dire polar bear predictions knowing that the PBSG parent organization (IUCN) supports the pointed criticisms of these projections made by modeling experts:
2014 November 9: BBC: Can polar bears be saved?
2014 November 4: Global warming’s early victims: Watch live as polar bears wait for sea ice to form
2014 October 19: The only solution for polar bears: ‘stop the rise in CO2 and other greenhouse gases
2014 September 3: The Polar Bear’s Vanishing World
Problems with the models1
Leading the polar bear prediction critique is distinguished professor of Ecology and Evolution, and mathematical modeling expert, H. Resit Akçakaya from Stony Brook University, New York (see Reference section) – who also happens to Chair the Standards and Petitions Subcommittee for the IUCN Red List.
Referring specifically to Amstrup and colleagues’ Bayesian Network model papers, Professor Akçakaya had this to say to PBSG members (including Amstrup) at their June meeting:
“First, BN models are mainly a vehicle for placing expert opinion into a common framework. They are not straightforward to update on the basis of observed data and there is concern that data would not be able to overwhelm the priors. Second, the BN model structure is not based on population dynamic theory. Third, the results from the BN approach are not applicable to Red List Criteria A or C, which require estimates of the amount of the decline not the probability of decline. Finally, the results are not applicable to Red List Criteria E, which requires quantitative not qualitative states.” [my bold]
The only criteria available to the PBSG for making a case that polar bears should be classified as ‘vulnerable’ on the next IUCN Red List is to use Criteria A3 (“population reduction expected in future”), in conjunction with Criteria E (“any form of analysis that estimates the extinction probability of a taxon based on known life history, habitat requirements, threats, and management options”).
By all other IUCN criteria, polar bears are currently either ‘data deficient’ or ‘least concern’ — only a much-revised PBSG assessment (with more data), that predicts population declines ≥30% within 30-36 years, will allow polar bears to be listed as ‘vulnerable’ by the IUCN Red List in 2015. PBSG-member biologists are scrambling to pull their case together, focusing their efforts on preventing an IUCN demotion of polar bear status.
[New IUCN guidelines were made available in February 2014, with specific reference to dealing with future risks from climate change – see them here]
Implications of the IUCN critique
Thumbs up to the IUCN for tightening their standards for mathematical models used for species declared ‘vulnerable,’ ‘near vulnerable,’ or ‘endangered’ on their Red List of Threatened Species, especially when future risks from predicted climate change are used.
Who would have guessed that the IUCN would be the only ones capable of holding polar bear biologists to a higher scientific standard?
On the face of it, it appears to be good news. However, I have reservations about rejoicing.
One reason is that Akçakaya and other IUCN modeling specialists are actively assisting PBSG biologists (see the minutes here) to make a model capable of predicting a future decline in polar bear numbers. That suggests to me that they are all working towards a predetermined outcome – listing polar bears as ‘vulnerable’ when the bears in fact show few, if any, convincing signs of being harmed by human-caused climate change (discussed here and here).
[Evidence for population responses to natural variation in sea ice coverage and subpopulation numbers reaching carry capacity — yes; human-caused sea ice changes — no]
Another is the rather blind acceptance by the IUCN of IPCC future climate predictions as settled science — even then, the most recent IPCC version is not mentioned (the 2014 IUCN guidelines refer only to the 2007 IPCC AR4 version; what’s the point of having an updated AR5 (2013) if no one uses it)?
Lastly, it is disturbing to me that Akçakaya and the IUCN have not made any of these concerns about the upcoming polar bear conservation assessment public [the PBSG have recently acknowledged the issue but only in the minutes of their meeting posted online]. That silence suggests backroom deals are being brokered to save PBSG biologists and the IUCN from the embarrassment of having to demote polar bears to a status of ‘least concern,’ ‘near threatened,‘ or even ‘data deficient.’
Why, for example, has Resit Akçakaya not raised these concerns about Amstrup’s models in the scientific literature? And why has he not made public the weakness of the ESA case for listing polar bears as ‘threatened’ in 2007 — to protect American biologists and US Fish and Wildlife officials from embarrassment?
Make no mistake – flawed predictive conservation models promoted world-wide for eight years as sound science is (or should be) a huge embarrassment for all those concerned, not just Amstrup. These model issues should have been raised publicly long before this year — and addressed — not only by the IUCN but by ESA officials in the USA as well.
Footnote 1. This is not the first criticism of these polar bear models but they are the first that Amstrup and colleagues have not been able to ignore. Earlier this year, Canada successfully defended it’s lower-threat status assessment of polar bears, based primarily on criticisms of Amstrup’s models (discussed in my House of Lord lecture here). The reason for the dismissal of the NAFTA challenge got no coverage in the media but was in the reports.
Well before that, Armstrong et al. (2008) published a paper describing some pointed criticisms based on the large number of accepted forecasting principles absent from Amstrup et al.’s 2007 pre-publication government report. It didn’t do much good: Amstrup et al.’s (2009) haughty rebuttal stated: “We evaluate the AGS audit and show how AGS are mistaken or misleading on every claim.”
However, the criticisms of the IUCN cannot be so easily dismissed. Amstrup and colleagues must now address the serious short-comings of the predictive models they previously insisted were sound science.
Armstrong, J.S., Green, K.C. and Soon, W. 2008. Polar bear population forecasts: A public-policy forecasting audit. Interfaces 38(5):382–405. http://pubsonline.informs.org/doi/abs/10.1287/inte.1080.0383 [See also this short editorial http://pubsonline.informs.org/doi/abs/10.1287/inte.1080.0398]
Amstrup, S.C., DeWeaver, E.T., Douglas, D.C., Marcot, B.G., Durner, G.M., Bitz, C.M., and Bailey, D.A. 2010. Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence. Nature 468:955-958. http://www.nature.com/nature/journal/v468/n7326/abs/nature09653.html
Amstrup, S.C., Marcot, B.G., Douglas, D.C. 2008. A Bayesian network modeling approach to forecasting the 21st century worldwide status of polar bears. Pgs. 213-268 in Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications, E.T. DeWeaver, C.M. Bitz, and L.B. Tremblay (eds.). Geophysical Monograph 180. American Geophysical Union, Washington, D.C. http://onlinelibrary.wiley.com/doi/10.1029/180GM14/summary and http://alaska.usgs.gov/science/biology/polar_bears/pubs.html
Amstrup, S.C., Caswell, H., DeWeaver, E.T., Stirling, I., Douglas, D.C., Marcot, B.G. and Hunter, C.M. 2009. Rebuttal of “Polar bear population forecasts: a public-policy forecasting audit.” Interfaces39(4):353-369.
PAPERS FROM Akçakaya’s “Climate Change Impacts on Biodiversity” Lab:
Akçakaya, H.R., S.H.M. Butchart, G.M. Mace, S.N. Stuart, and C. Hilton-Taylor. 2006. Use and misuse of the IUCN Red List Criteria in projecting climate change impacts on biodiversity. Global Change Biology 12:2037-2043. [PDF]
Akçakaya*, H.R., S.H.M. Butchart, J.E.M. Watson, R.G. Pearson. 2014. Preventing species extinctions resulting from climate change. Nature Climate Change 4:1048-1049. http://www.nature.com/nclimate/journal/v4/n12/full/nclimate2455.html
Stanton, J.C., K.T. Shoemaker, R.G. Pearson, R.G., and H.R. Akçakaya*. 2014. Warning times for species extinctions due to climate change. Global Change Biology (in press) DOI: 10.1111/gcb.12721 http://onlinelibrary.wiley.com/doi/10.1111/gcb.12721/abstract