An indicator published by the Global Fund for Nature (WWF) testifies to continuous erosion of biodiversity.
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Every two years, the Global Fund for Nature (WWF) assesses the abundance of populations of wild vertebrates, through its “living planet” (IPV). And, every two years, this indicator describes a decline that increases, inexorably. According to the latest edition of the report, published Thursday, October 13, the populations of birds, fish, mammals, amphibians and reptiles declined on average 69 % between 1970 and 2018. In 2020, the same indicator reported a fall of 68 %.
“A decrease of 1 % in two years is colossal, and we have lost 10 points in ten years, underlines Arnaud Gauffier, the director of WWF programs. On very low populations, it can be dramatic and Living to extinctions. The mere fact that this indicator does not improve is catastrophic. “Vertebrates represent less than 5 % of known animal species, but are the most followed.
large disparities
In barely fifty years, according to the IPV, the populations of plains gorillas decreased by 80 %; Those of African forest elephants, classified as a critical danger of extinction, 86 %. The populations of sharks and ocean lines have also collapsed (-71 %). Other populations – about half of those who have been studied – are however stable or increase.
Developed by the London Zoological Society, the living planet index calculates an average trend for tens of thousands of populations of land, sailors and fresh water. This year, 31,821 populations representing 5,230 species were taken into account, or 838 new species and 11,011 more populations compared to 2020 – a considerable increase. The number of fish species (+ 29 %) and birds (+ 95 %) in particular, as well as data from previously under-represented regions, such as Latin America and the Caribbean, have been largely expanded.
At the end of 2020, researchers had judged, in an article published in Science, that this indicator gave a “catastrophic” vision of the erosion of biodiversity, believing that The extreme decrease of certain populations affected the overall average “disproportionate”. For this new edition, the IPV has been recalculated by excluding certain species or populations. “This confirmed that the index was not determined by declines or extreme increases,” write the authors of the report.
The loss of biodiversity is particularly complicated to summarize in a figure or a measure which would make consensus, the phenomenon being multidimensional. “The IPV makes it possible to make useful comparisons from year to year and to give an order of magnitude of the loss of biodiversity, explains Michel Loreau, director of research at the CNRS. But I prefer other more specialized and homogeneous studies on The decline of birds or insects, which are just as alarming. “
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