This is the conclusion reached by researchers from Stanford University and the Institute of Ecology of the National Autonomous University of Mexico.
In 2015, ecologist Gerardo Ceballos led a study that used conservative estimates to reveal the huge discrepancy between the usual ("background") extinction rates and the extinction stream we see today.
The average rate of extinction of vertebrate species has been found to be two per 10,000 species every 100 years. In the XX and XXI centuries, this figure increased 114 times. According to the researchers, this clearly demonstrates that a mass extinction is happening right before our eyes.
“We can confidently conclude that current extinction rates are exceptionally high, that they are increasing, and that they suggest a mass extinction - the sixth of its kind in Earth's 4.5 billion years of history,” the researchers wrote in 2015. The sixth mass extinction itself is better known as the Holocene, as it coincides with the modern era of the Holocene.
Now Ceballos and his colleagues have conducted a new study that has come to even less optimistic conclusions. According to the authors of the work, the already rapid rate of extinction of vertebrates will increase dramatically in the future.
For the study, the team used data from the IUCN Red List and Birdlife International to study populations of vertebrates that are critically endangered, having lost most of their historical range and retained fewer than 1,000 living individuals worldwide.
According to the researchers, 1.7% of all terrestrial vertebrates or 515 species correspond to this description. Moreover, about half of them have less than 250 individuals in the population.
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Another 388 species are doing slightly better, retaining 1,000 to 5,000 individuals in the population. However, 326 of them live in the same regions as the 515 species mentioned above. This suggests that they are likely to be exposed to the same threats, including destabilizing ecosystems, disrupting food webs, deforestation, pollution and other human influences.
Scientists explain that the close ecological interaction of endangered species leads to a joint extinction. That is, one disappearance gives rise to another.
These “cascades of extinction”, caused by the loss of some key species in ecosystems, are a well-known phenomenon in ecology and place enormous pressure on animal populations. Therefore, according to the authors of the study, mass extinction is only gaining momentum.
According to scientists, if during the entire XX century 543 species of terrestrial vertebrates became extinct, then over the next 20 years about 540 species will become extinct. This means that the rate of extinction is already 117 times higher than the background rate and higher than the researchers' own estimates five years ago.
Scientists note that it is not too late to take measures to relieve human pressure on the biosphere. This can be accomplished by imposing broad bans on the trade in wild species, slowing deforestation and recognizing all animal populations with fewer than 5,000 as endangered.
Scientists agree that this issue is the most pressing environmental problem, but it can only be solved with the right priorities.
“The tragedy is that we have the knowledge to save species from extinction, and do it cheaply in a global context. But it just isn't getting enough attention from society and governments,”concludes ecologist Chris Johnson of the University of Tasmania in Australia, who was not involved in the study.
Author: Mikhail Sysoev