Humans have caused so many changes to our planet that some experts say we are on par with the mass extinctions of eons past. We are comparable to the asteroid that wiped out most of the dinosaurs or the Great Dying that wiped out almost all life on Earth. Some have suggested calling our current geologic era the “Anthropocene,” derived from the Greek word “anthropo,” meaning “human.”
While it sounds like an achievement that we can exert enough influence to change our home planet, human activity has done so in dangerously unsustainable ways. According to a recent study published in the journal, this is indeed the case Proceedings of the National Academy of Sciences, humans have caused so many species extinctions in the last 500 years that if we had never existed, it would have taken 18,000 years for the same species to disappear naturally. After all, animals go extinct on a regular basis over geological timescales, but this mass extinction is largely caused by humans.
“The mutilation of the tree of life alters the systems in which humans and all other living organisms have evolved.”
And that’s just the first sobering statistic from the study. Authors Gerardo Ceballosa and Paul R. Ehrlich of Stanford University and Mexico’s Universidad Nacional Autonoma de Mexico examined the classification status of 5,400 vertebrate genera (excluding fish), a task that included 34,600 species. Scientists then determined that 73 animal genera had become extinct since 1500 AD.
“There is no doubt that the human-caused sixth mass extinction is more severe than previously thought and is accelerating rapidly,” the authors said. This means that animals are disappearing 35 times faster than in the last million years – i.e. before the start of the Anthropocene. While there might be a silver lining to this news if humanity were to at least halt the trends leading to this mass extinction, the exact opposite is true.
“Such mutilation of the tree of life and the resulting loss of the ecosystem services that biodiversity provides to humanity poses a serious threat to the stability of civilization.”
“Current generic drug extinction rates will increase over the next few decades due to drivers accompanying the growth and consumption of the human enterprise, such as: B. habitat destruction, illegal trade and climate disruption, are likely to accelerate significantly,” write Ceballosa and Ehrlich. “If all now-endangered genera disappeared by the year 2100, extinction rates would be 354 (on average) and 511 (for mammals) times higher than background rates, meaning that 106,000 and 153,000 genera, respectively, would have been lost over three centuries [years] become [extinct] in the absence of people.
They concluded: “Such mutilation of the tree of life and the resulting loss of the ecosystem services that biodiversity provides to humanity poses a serious threat to the stability of civilization.”
To illustrate the scale of the mass extinction epidemic, the authors mention that “at the beginning of the 20th century, there were approximately 10,000,000 African elephants and today only about 450,000 remain,” a decline of over 95%. Still, overall, the researchers found that “most documented extinctions occurred in birds, followed by amphibians, mammals, and finally reptiles.”
As for the many lost bird species, some of the most extinct species include giant birds such as the elephant birds (Aepyornithiformes) in Madagascar and the moas (Dinornithiformes) in New Zealand. The researchers also added that while there is “sparse” data, most of the lost genera appear to have only disappeared in the last two centuries.
The authors point to some species, such as the Steller’s manatee, which went extinct around 1768, but many other species – including passenger pigeons, Tasmanian tigers and the yellow river dolphin – have been “extinct since modern science began to pay attention.”
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“There is no doubt that the human-caused sixth mass extinction is more severe than previously thought and is accelerating rapidly.”
Scientists say it’s a bad thing that so many extinctions occurred at a time when humanity had the technology to record them. At this rate of extinction, we are in for a very unpleasant shock in the near future.
“In other words, the projected loss of genera over three centuries (1800 to 2100) would have cost 106,000 [years] for all vertebrates and up to 153,000 [years] so that they become mammals [extinct] below normal background rates,” the authors write. They don’t mince words, describing a “biological holocaust” and comparing us to renegade landscapers chipping away at every branch of life. “The mutilation of the tree of life alters the systems in which humans and all other living things have evolved,” they warn.
“During past mass extinctions, there was no species that had the power or interest to stop extinctions, and there was no conscious interest in conserving biodiversity,” they add. “Today there is a species that should know that it cannot wait millions of years for its life support systems to be restored after a mass extinction.”
“Today there is a species that should know that it cannot wait millions of years for its life support systems to be restored after a mass extinction.”
This isn’t the first recent study to underscore Earth’s worsening ecological crises. According to a recent study in the journal Scientific advancesHumanity is in existential danger to six of its nine planetary boundaries, or the framework that determines how safely humanity can operate within Earth’s biological and physical boundaries before it undermines our own ability to survive. These include the maintenance of a stable climate, land system changes, freshwater changes, novel substances (such as plastics, pesticides and industrial chemicals), and the flows of biological and geological chemicals.
“We live by using the earth’s resources and throwing our waste into the open environment,” said the study’s lead author, Dr. Katherine Richardson, professor of biological oceanography at the Sustainability Science Center at the University of Copenhagen, told Salon in an email. “Earth’s resources are limited and our demand exceeds its supply. You can celebrate even if your bank account balance goes down – but you can’t celebrate forever, and that’s the situation humanity has put itself in.”
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