A new study in the Proceedings of the National Academy of Sciences claims to “provide strong empirical support for the assertion that anthropogenic climate change is now a major threat to global biodiversity”… just don’t ask for an example.
The study authors claim to have reviewed 1,120 relevant studies published since 2005, extracting data from 74 of them. They report that:
Mean extinction probability across studies making predictions of the future effects of climate change was 7% by 2100 compared with 15% based on observed responses. After taking account of possible bias in the type of climate change impact analyzed and the parts of the world and taxa studied, there was less discrepancy between the two approaches: predictions suggested a mean extinction probability of 10% across taxa and regions, whereas empirical evidence gave a mean probability of 14%.
They conclude that:
Our metaanalysis [sic] showing high predicted levels of extinction, backed up by consistent data for changes that have already occurred, shows the need to give climate change high priority in conservation planning and to communicate its potentially wide-ranging consequences to policy makers and the wider public.
I contacted study author Ilya Maclean and asked:
Could you please cite a few examples of studies in which you have high confidence that show recent climate change has caused/will cause species extinction?
I believe readers would be interested in knowing the sort of study data that you rely on as input to your meta-analysis.
Our study does not make the claim that there are existing examples in which climate change has caused/will cause species extinction so I cannot provide you with these.
Three hours after receiving that response, I followed up with these questions:
How do you reconcile your statement (in the abstract) about your study providing “strong empirical support for the assertion that anthropogenic climate change is now a major threat to global biodiversity” with the absence of actual examples?
Are you saying that a meta-analysis of unverified predictions constitutes empirical evidence that climate change threatens biodiversity?
Maclean responded as follows:
I am out of office until Tuesday 12th July.
Maybe Maclean really did make himself unavailable for interviews until the day after his study comes out. Or maybe he just doesn’t want to answer the questions. I’ll let you know if he responds.
Meantime, enjoy George Carlin on species extinction (WARNING: LANGUAGE).