Not much time for blogging, but two technical critiques of the Harvey et al. paper have recently been posted, which you might like to read at your leisure. I will update this post when I can if more critiques appear plus I’ve provided a list of previous posts (my and others) on this issue.
“Polar Bears, Inadequate data and Statistical Lipstick“ (18 Decemeber 2018, RomanM writing at ClimateAudit)
“Polar bear attack paper invalidated by non-independent analysis” (Cross posted 14 December 2017 at ClimateScepticism from the blog of Shub Nuggarath, 12 December 2017).
UPDATE 19 December 2017: Richard Tol has posted a draft of his critique, which was itself updated 20 December “Lipstick on a bear” in which he concludes:
“In sum, Harvey et al. (2017) play a statistical game of smoke and mirrors. They validate their data, collected by an unclear process, by comparing it to data of unknown provenance. They artificially inflate the dimensionality of their data only to reduce that dimensionality using a principal component analysis. They pretend their results are two dimensional where there is only one dimension. They suggest that there are many nuanced positions where there are only a few stark ones – at least, in their data. On a topic as complex as this, there are of course many nuanced positions; the jitter applied conceals the poor quality of Harvey’s data. They show that these is disagreement on the vulnerability of polar bears to climate change, but offer no new evidence who is right or wrong – apart from a fallacious argument from authority, with a “majority view” taken from an unrepresentative sample. Once the substandard statistical application to poor data is removed, what remains is a not-so-veiled attempt at a colleague’s reputation.”
UPDATED 20 December 2017: Lead author of the Bioscience attack paper Jeff Harvey talked to an Amsterdam newspaper about the backlash to the paper, original Dutch and English translation here.
Predicted sea ice changes (based on 2004 data) at 2020, 2050, and 2080 that were used in 2007 to predict a 66% decline in global polar bear numbers vs. an example of the sea ice extent reality experienced since 2007 (shown is 2012). See Crockford 2017 for details.
Read a short summary of the paper that Harvey et al. don’t want you to know about here:
Crockford, S.J. and Geist, V. 2018. Conservation Fiasco. Range Magazine, Winter 2017/2018, pg. 26-27. Pdf here.
The paper they don’t want you to read is here:
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. https://doi.org/10.7287/peerj.preprints.2737v3
The paper being criticized (Harvey et al. 2017, in press: “Internet blogs, polar bears, and climate-change denial by proxy”, Bioscience, open access) is available here. There is a supplementary data file available here and the data for the principal component analysis is available here and (h/t to R. Tol), the R code is available here
More on this after Christmas but for now a list of previous blog posts of mine and others is provided below. Continue reading