The mass extinction of animals accelerates
Tuesday, 11 July 2017 11:38
Tuesday, 11 July 2017 11:38
Look at this article
Rhinos, gorillas, but also of the lions in the past security… The mass extinction of animals is accelerating and there is without doubt more than 20 or 30 years to curb this “annihilation organic,” which threatens “the foundations of human civilization”, warns a new study.
More than 30% of vertebrate species are in decline, both in terms of population and geographic distribution, indicates the study published in the journal Proceedings of the National Academy of Sciences (PNAS).
“It is a destruction of life that occurs at the aggregate level, even if the species to which belong these populations still exist somewhere on Earth,” says one of the authors of the study, Rodolfo Dirzo, professor of biology at Stanford University.
“The sixth mass extinction is already here, and the window for action in order to act effectively, is very close, perhaps two or three decades at most,” they write. It is an “attack frightening against the foundations of human civilization.”
The Earth has so far experienced five mass extinctions, the last one in date, that of dinosaur, dating back 66 million years ago. According to most scientists, a sixth is in progress. For the authors of this new study, it is already “gone further” than thought until now, in the light of previous studies that focused exclusively on the extinction of species and not only on the size and distribution of populations.
Researchers from Stanford University and the national autonomous University of Mexico interested in the populations of wild animals.
They have drawn up a map of the geographic distribution of 27 600 species of birds, amphibians, mammals and reptiles, a sample representing nearly half of the terrestrial vertebrates known. They have analyzed also the population declines in a sample of 177 species of mammals, for which they had detailed data, over a period ranging from 1900 to 2015.
More than 20 000 lions
On the 177 mammals, all have lost at least 30% of their geographical areas of distribution and over 40% have lost more than 80%.
The mammals of South Asia and South-East are particularly affected: all species of large mammals analysed have lost more than 80% of their geographic range, indicate the researchers, in a news release accompanying the study.
Approximately 40% of all mammals, including rhinos, orang-utans, gorillas and many of the big cats – survive now on 20% or less of the territories in which they once lived.
The decline of wild animals is attributed mainly to the disappearance of their habitat, overconsumption of resources, pollution or the development of invasive species and diseases. Climate change could also contribute more.
This movement alarming has recently accelerated.
“Several species of animals that were relatively safe there are ten or twenty years”, such as lions and giraffes, are now in danger”, according to this study.
The lion (Panthera leo), for example, was present on the greater part of Africa, in the south of Europe and the Middle East, to the north-west of India. “It is now reduced to populations that are scattered in sub-saharan Africa, with a residual population in the Gir forest of” (western India). “A huge majority of the population of lions has gone,” say the authors.
According to the international Union for the conservation of nature (IUCN), there are only 20 000 lions in the world.
These losses are “massive” in terms of populations and species are “a prelude to the extinction of many other species and the decline of the ecosystems that make civilization possible,” warns the lead author of the study, Gerardo Ceballos.
The researchers call for action to tackle the causes of decline of wild life, including overpopulation and overconsumption.