It’s gratifying to see the essay by Johnston getting the attention it deserves (at WUWT and JoNova) after Pielke brought it to our attention. Johnston reviews many areas of climate science in 82 pages of readable prose and concludes:
Insofar as establishment climate science has glossed over and minimized such fundamental questions and uncertainties in climate science, it has created widespread misimpressions that have serious consequences for optimal policy design.
Apparently somebody asked “What does a lawyer know about climate science?”. Well, firstly, he is an environmental law professor. Secondly, the areas he writes about where I am knowledgeable show surprising insight. His assessment of estimates of species loss (20-30%) due to global warming restates exactly what I said at the time in Biased Towards Extinction:
Given the extensive and foundational criticism by biologists of the methodology underlying the species loss probability prediction generated by Thomas et al., the IPCCâ€™s publication of that probability without qualification seems dangerously misleading, and in any event clearly exemplifies the rhetoric of adversarial persuasion, rather than â€œunbiasedâ€ assessment.
Of five â€œproblematicâ€ uncertainties and complications that he raises (and there are many more I might go into) of the Thomas et al. study, one that I mentioned in the CO2 science editorial is particularly offensive:
v) Finally, and perhaps most strikingly to my laypersonâ€™s sensibilities, the methodology employed by Thomas et. al. will â€œinevitably detect extinctions. Negative changes in the size of a speciesâ€™ range contribute to an increased extinction risk overall, while positive changes have no net effect on extinctions,â€ this despite the fact that
locally, â€œthe net effect on diversity at any one locality might well be positive, as species spread towards the poles from the most species-rich habitats near the equator.â€
Thomas and authors achieved this statistical slight-of-hand by ‘cherry picking’ all species whose home ranges were reduced by warming, and removing those whose home ranges increased. The change in the size of home range is assumed to affect the survival of the species.
When I questioned Thomas about this, his defense was that the method had been approved by a number of eminent conservation biologists who found it perfectly fine. He said that those species with reduced range were are greater risk of extinction from global warming, while those with increasing range were of course going to be OK.
However, it takes a layman’s sensibilities to see, apparently, that for every species that decreases its range another increases its range, therefore the overall rate of extinctions does not change. If overall rate of extinctions does not change, then no increase in extinctions could be expected from global warming.
I tried to explain this trivial point to the coauthors and three rounds of reviewers without success. The final straw was the assertion of one reviewer to the effect that “We know that global warming is going to increase extinctions, so your analysis must be wrong.” I concluded, as Jason Johnston did, that the field “exemplified the rhetoric of adversarial persuasion, rather than ‘unbiased’ assessment.” – i.e which is, I suppose, code for ‘green advocacy’.
So, read the summary of the state of play on species losses by Johnston. He mentions the article I helped prepare with 17 scientists in related fields rebutting Thomas et al. which has largely been ignored by the conservation field. He also touches on the murky origins of the iconic statement that:
â€œ[a]pproximately 20-30% of plant and animal species assessed thus far are likely to be at increased risk of extinction if increases in global temperature exceed 1.5 â€“ 2.5Â°C.â€
In what could be called a Species-gate, this statement was eventually attributed to Thomas et al. by the IPCC, despite the fact that the Thomas et al. methodology and manuscript do not mention probability. The determination of species ‘committed to extinction’ is not quantified by probability.
As if anybody cares about accuracy and precision anymore. The sad part is that such papers as Thomas et al., and the minimization of fundamental questions and uncertainties even when legitimate problems are raised, lead people to believe that “the science is settled”, and take us further from knowing the real truth about climate change and survival of species.