We’ve all heard of the natural doomsday events caused by volcanoes and giant asteroids that wiped out most of the world's flora and fauna millions of years ago. Now scientists are warning we may be poised for the next great wave of extinctions, but this time humans may trigger the apocalypse.
In a series of sobering studies published in the Science journal this week, scientists are cautioning that we may be at a tipping point in terms of a potential catastrophic loss of the world’s biodiversity.
They are pointing to the decline of some 320 vertebrates that live on land in just the last 500 years. Populations of many major large-sized species, like elephants and polar bears, are at the greatest risks currently, with their numbers nose-diving by 25 per cent. In fact around 16 to 33 per cent of all vertebrate species are considered threatened or endangered.
The situation for invertebrates, like insects and worms, is even more worrisome: in just the last four decades we've seen a decline of about 45 per cent in their global abundance. These tiny creatures, while not as glamorous, are the backbone of entire ecosystems, say researchers, and their loss can signal the eventual breakdown of the entire system.
Making matters worse, increasing human populations lead to habitat loss. Animals will soon be running out of places to hide from the growing numbers of hunters and poachers. One of the studies focused on the cascading effects of the removal of the larger species from ecosystems. Predation rates are found to drop while disease-carrying vermin numbers increase.
"Where human density is high, you get high rates of defaunation, high incidence of rodents, and thus high levels of pathogens, which increases the risks of disease transmission," said one of the study authors Rodolfo Dirzo, a researcher at the Stanford University in a press statement. "Who would have thought that just defaunation would have all these dramatic consequences? But it can be a vicious circle."
These dramatic changes in the richness of the world’s flora and fauna reservoir in recent years have the international team of researchers warning that Earth may already be in the midst of the sixth great extinction event our planet has experienced.
The new doomsday scenario is being dubbed the ‘anthropocene defaunation,’ referring to the human-caused extinction of animals. The previous five global extinction events that swept the Earth were all forces of nature, like asteroid impacts and volcanic eruptions. One species alone is seemingly becoming the driving force behind the sixth extinction.
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"Ironically, we have long considered that defaunation is a cryptic phenomenon, but I think we will end up with a situation that is non-cryptic because of the increasingly obvious consequences to the planet and to human well-being," said Dirzo.
But not all is doom and gloom.While there is an upwards trend for humans to wipe out wildlife and their habitats, we may have the power to slow or reverse it thanks to aggressive conservation measures. Hope may very well be found through re-introduction and breeding programs and even the use of cloning technology to bring back species from the brink of extinction.
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