Polar bear researchers have been doing capture/recapture studies in Western Hudson Bay for decades yet most of the data claimed to be critical for assessing effects of human-caused global warming on this species have not been published. I raised this point in one of my early blog posts (27 Sept 2012) but the situation has not changed in 6 years. Here’s an update.
Years ago now, in an oft-cited paper, Stirling and Derocher (2012) claimed to summarize the evidence that climate warming was negatively impacting polar bear health and survival. Several life history parameters were considered crucial, particularly body condition.
Despite almost a dozen papers (and perhaps more) on various aspects of WH polar bear health and life history studies based on capture/recapture data published since 2004 (e.g. Castro de la Guardia 2017; Lunn et al. 2016; Pilfold et al. 2017), none have reported the body condition data that supposedly support the claim that sea ice loss is having a severe impact — and the same is true for litter size, proportion of independent yearlings, and cub survival.1
Posted in Conservation Status, Life History, Population, Sea ice habitat
Tagged body condition, capture, Derocher, fat, field work, Lunn, mark-recapture, mass, polar bear, protocol, Sciullo, sea ice, Stirling, unpublished data, weight, western hudson bay
A newly-published paper by Martyn Obbard and colleagues in the journal Arctic Science claims a 17% decline in abundance of polar bears in the Southern Hudson Bay region after years of reduced sea ice and declining body condition (Obbard et al. 2018). The decline in numbers was not statistically significant but an additional statistical analysis (“Monte Carlo simulation”) not applied to any other estimate in recent years suggested the decline could be real, so a real decline is what was reported to the press.
Only one Canadian Press story has so far been circulated amongst outlets in the media (published hours after the paper appeared online, not at the same time), suggesting there was no press release issued for this study. Odd, that — especially if the decline is as real and significant as the authors suggest.
While no evidence was provided for a correlation of this decline in numbers to recent (2012-2016) sea ice decline, previous evidence from the region (Obbard et al. 2016) showed a decline in body condition was correlated only with much later than usual freeze-up, a situation that did not occur from 2012 to 2015 (freeze-up was late in the fall of 2016 but occurred months after the Obbard et al. (2018) survey was completed).
Moreover, the paper reports that a decline in survival of yearling cubs (from 12% of the population in 2011 to 5% in 2016) was not associated with especially poor sea ice conditions in spring. We are likely to see a follow-up paper next year reporting the body condition and sea ice data from this study (as for the previous survey: Obbard et al. 2015, 2016), but there is no suggestion in this paper that body condition declined further from 2011/2012 levels or that sea ice conditions deteriorated markedly enough after 2012 to precipitate a population decline.
UPDATE 11 June 2018: See below, more recent versions of population and status assessment maps has been issued by Environment Canada that conclude Southern Hudson Bay is “likely declined.”
Josh’s ‘stupidest paper ever’ cartoon is a reminder of the depths to which some people will descend to silence the voices of rational scientific debate just as the authors of the 2018 Harvey et al. BioScience paper qualifies it for the honour of poster child of the reproducibility crisis in science.
By insisting — repeatedly and as recently as this month — that the information they released as supplementary data (find it here) was all that was used to construct the two figures in the paper (see Rajan and Tol 2018), the authors tacitly admit:
1) the data used to construct the figures were not derived from the methods they said they used
2) the work is not replicable
In other words, it is not science. That surely qualifies the Harvey et al. (2018) paper for the honour of poster child of the reproducibility crisis in science, discussed here and here (Baker 2016; Nosek et al. 2015). It’s an example the public will readily grasp, since the data said to have been used are easily accessible (and understood) by anyone who uses the Internet.
Below is the letter outlining the data release issue sent more than a week ago (18 May 2018) by Dr. Richard Tol, University of Sussex, to the president of the
university highest academic authority in the Netherlands, where Jeff Harvey, lead author of the Harvey et al. 2018 BioScience paper, is employed as an academic [h/t R. Tol for the correction]. While Koninklijke Nederlandse Akademie van Wetenschappen [KNAW] in Amsterdam has a clearly stated data sharing policy, it is clearly not being upheld for the Harvey et al. paper — which nullifies the point of having a policy at all.
Posted in Scientists hit back
Tagged Amstrup, BioScience, crisis, Harvey, KNAW, Lewandowsky, Mann, mouse mat, mouse pad, polar bear, reproducibility, Stirling, stupidest paper ever