The findings of the new WWF report have been misinterpreted by many - although the real picture is still grim, notes a well-known science journalist in Britain and the United States, and explains how to properly interpret the report's findings. He also gives a hypothetical scenario to clarify the situation with the decline in the animal kingdom.
On Monday, the media and social media were agitated by the claim that "since 1970, humanity has destroyed 60% of animals," as the Guardian tweeted, among others. This is a dramatic and staggering figure based on the latest World Wildlife Fund (WWF) report, co-produced by the Zoological Society of London, The Living Planet Index.
But that's not exactly what the report says.
The Living Planet Index team built on previous research in which scientists estimated the size of various animal populations using a variety of methods, whether direct counts, camera traps, satellites, or something indirect, such as nests or footprints. The group compared these estimates for 16.7 thousand populations of mammals, birds, reptiles, amphibians and fish, numbering four thousand species (the term "populations" here means foci of distribution of individuals of this species that live in different geographical areas - author's note).
This covers only 6.4% of the 63 or so thousand species of vertebrates, that is, animals with a skeleton, that are reported to exist on our planet. To figure out how the whole set behaves, the team adjusted their numbers to account for any bias in their data. For example, vertebrates in Europe have been studied more extensively than in South America, and the most vulnerable creatures, such as elephants, have been more thoroughly studied (and easier to count - author's note) than very common ones, such as pigeons.
Ultimately, they found that between 1970 and 2014, vertebrate populations declined by an average of 60%. This does not mean at all that humans killed 60% of the animals - a distinction that is clearly stated in the technical update of the report. "This is not a census of all wild animals, but reports of how wild populations have changed in size," the authors write.
To understand the difference, imagine you have three populations: five thousand lions, 500 tigers, and 50 bears. Four decades later, you have only 4.5 thousand lions, 100 tigers and five bears left (oh my god - author's note). These three populations have declined by 10%, 80% and 90%, respectively, which gives us an average reduction of 60%. But the total number of real animals fell from 5550 to 4605, that is, by only 17%.
For similar reasons, it is also not true that we “wiped out more than half of the world's wildlife populations” or that we can be accused of “eradicating 60% of animal species” or that “the global wildlife population declined by 60% between 1970 and 2014. . All of these things may well be true, but they all speak of indicators that were not measured in the Living Planet Index study.
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Uncertainty is further magnified when one remembers that 63,000 vertebrate species are vastly outnumbered by the countless millions of invertebrate species - spineless creatures such as insects, worms, jellyfish and sponges that make up the majority of animals. The situation with them is not so clear, because scientists, in general, spent less time on them. They are more difficult to study and receive less attention than vertebrates, which are considered to be more charismatic - although there are plans to do them justice.
The population decline by an average of 60% also hides information about the fate of individual species. In the hypothetical scenario above, the lions are still mostly okay, the tigers are in trouble, and the bears are on the brink of extinction. And of the species examined in this Living Planet Index study, half are increasing in numbers, while the other half are decreasing. This means that for those whose numbers are actually declining, the prospects are even worse than meets the eye.
None of this should confuse humanity. Since prehistoric times, humans have destroyed so many mammalian species that it would have taken three to seven million years of evolution to develop an equivalent diversity. At least a third of amphibians are on the verge of extinction due to climate change, habitat loss and an apocalyptic killer fungus. Even invertebrates were not spared. There may be less information on them, but the existing data paints a disturbing picture of the rapid disappearance of insects - even in supposedly pristine forests. Meanwhile, in the oceans, coral reefs are bleaching too quickly to regenerate, with half of the Great Barrier Reef's corals dying since 2016. All of this evidence points to a period of "biological destruction"which some have compared to the five major mass extinctions of the past. When reality itself is a sensation, there is no need to look for sensation elsewhere.
Bottom line: everything is bad. Then it can be argued that adjusting the 60 percent indicator is too pedantic. Why find fault in the face of disaster? It's certainly important to wake people up, and if inaccurately reported statistics help do that, isn't that good?
I think not. Especially now, in an era when conspiracy theories are rampant and the highest government offices are easily the source of lies, it is more important than ever that those who warn about the fate of the planet are accurate in what they mean. At the same time, characterizing the problem and its scale is correct. If accuracy can be ignored for the sake of sensation, then you can just as well remove numbers from the air in a random order. And, remarkably, several media outlets such as Fox and NBC have succeeded in conveying the disturbing nature of the Living Planet Index study by accurately capturing its results. The dichotomy between accuracy and audience impact is false.
Ed Yong