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Biodiversity at risk or eco-propaganda?

by on 2019/06/05

The first Intergovernmental Panel for Biodiversity and Ecosystem Services (IPBES) Global Assessment summary for policy makers was released on the day prince Archie was born and the Met Gala took place. While nothing can quite compete for press attention with the birth of a royal baby and celebrities in fancy dress, the IPBES global assessment received plenty of press attention. Since late April, IPBES has featured in over 23 thousand articles. I have not read them all! Examples of press media coverage can be found here and here.

The Global Assessment is the collective work of hundreds of scientists, runs 1,500 pages long, and reviews about 15,000 scientific papers. For full disclaimer, the BioTIME database (which I co-lead) contributed an indicator to the report, although I was not involved in the report itself and have not read it, as it is not yet public.

The summary for policy makers is a carefully crafted document that is remarkably successful in summarising, in about 40 pages, a complex scientific literature about the hundreds of metrics that exist to quantify both biological diversity across land and sea, across different types of organisms and ecosystems, and also the benefits that humans derive from nature. As is typical of consensus reports, the summary reads as a document where every sentence has been scrutinised and can be traced back to the scientific literature. The summary is also remarkably balanced and clear as to the uncertainty regarding each statement. Inevitably, the press media focuses only on the most sensational of the evidence presented, and for this report the number that caught everyone’s attention was that of 1 million species at risk of extinction.

The summary is accurate in the distinction between being at risk and going extinct, and remarkably the press is (mostly) accurate in the wording as well. The way the one million species number is estimated is also transparent, and Andy Purvis (an author on the report) has since explained the calculations involved. We estimate there are 8.7 million species on the planet (although only about 1.7 million have been described so far). Of these, the IUCN has assessed about 98 thousand for extinction risk, and classified 12 thousand as vulnerable, 9 thousand as endangered and 6 thousand as critically endangered. In total, about 25% of the species assessed are in one of these three categories, but these are not evenly distributed among different types of organisms with amphibians and mammals having far higher proportions than insects. Given the high proportion of insects in the number of species on the planet, and the low proportion of insects assessed, multiplying the overall proportion of vulnerable species by the 8.7 million species estimated to exist would be an overestimate. Instead, the report uses weighed proportions for different organisms to arrive at the 1 million species number.

There are some examples of articles questioning the balance of the report and portraying it as an environmental propaganda attack on economic growth. As is typical of articles poor on arguments, they are laced with ad hominen attacks, and include long rebutted estimates, rather than the many indicators included on the summary report recently released. A particularly curious example is written by Toby Young for the Spectator. This article, titled “The UN’s extinction warning doesn’t add up”, proceeds to (largely accurately) describe how the numbers are actually obtained. There are many elements of truth in this article. For example, the full report is not available yet (and personally I am looking forward the opportunity to dig in to the report). One can debate whether or not to include all three threatened categories in the calculations, and as a biodiversity scientist, I get paid to debate that and other details in the ways in which we estimate how biodiversity is changing on the planet. Debate is part of the Scientific method, and biodiversity science is healthy in that respect. However, to focus on such details is extremely unfair on the depth and balance of the summary report as a whole. To put it simply, the claim that the numbers don’t add up is just empty rhetoric, and disproven even by the article itself.


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