In just the past 500 years no fewer than between 150,000 and 260,000 species may have gone extinct, scientists say.
In the history of life on earth there have been sixth mass extinctions of species with the most famous being the disappearance of dinosaurs from the planet. A Sixth Extinction is now upon us and this time the cause isn’t a force of nature but rather us.
People worldwide have been wreaking havoc with their environment and in just the past 500 years no fewer than between 150,000 and 260,000 species may have gone extinct, accounting for 7.5% and 13% of the 2 million or so species known to science.
A team of biologists from the University of Hawai’i at Manoa and the Muséum National d’Histoire Naturelle in Paris has reached this conclusion after extrapolating from estimates for land snails and slugs.
By including invertebrates into their study the scientists say they could confirm that the Sixth Extinction was indeed well underway despite denials by some scientists of the extent of the threats facing biodiversity.
“Drastically increased rates of species extinctions and declining abundances of many animal and plant populations are well documented, yet some deny that these phenomena amount to mass extinction,” explains Robert Cowie, a professor at the University of Hawai’i Manoa Pacific Biosciences Research Center who was the lead author of a new study.
“This denial is based on a biased view of the crisis which focuses on mammals and birds and ignores invertebrates, which of course constitute the great majority of biodiversity,” Cowrie adds.
In general wild animals on land are facing graver threats to their existence than marine creatures, although many species in the oceans are becoming endangered too, the scientists say.
Meanwhile, isolated island species such as those that inhabit the Hawaiian Islands are much more affected than continental species. Similarly, plants on land appear to be experiencing lower rates of extinction than terrestrial animals, especially larger slow-breeding ones.
Importantly, the driving causes of growing extinction threats almost everywhere are human activities.
“Humans are the only species capable of manipulating the biosphere on a large scale,” Cowie stresses. “We are not just another species evolving in the face of external influences. In contrast, we are the only species that has conscious choice regarding our future and that of Earth’s biodiversity.”
This means that people can still set things right, although there is no guarantee that all endangered species can be saved. The scientists point to conservation initiatives have achieved great success in bringing iconic species such as giant pandas in China and Amur tigers in Russia back from the very edge of extinction.
However, by their very nature such initiatives are limited in their scope, targeting specific species but leaving out many other similarly endangered yet less charismatic species such as invertebrates.
“Nonetheless, it is essential to continue such efforts, to continue to cultivate a wonder for nature, and to document biodiversity before it disappears,” the scientists observe.
What is needed is concerted action with forward-looking policies. One step in the right direction is to acknowledge the extent of the crisis and start acting accordingly.
“Despite the rhetoric about the gravity of the crisis, and although remedial solutions exist and are brought to the attention of decision-makers, it is clear that political will is lacking,” Cowie notes. “Denying the crisis, accepting it without reacting, or even encouraging it constitutes an abrogation of humanity’s common responsibility and paves the way for Earth to continue on its sad trajectory towards a Sixth Mass Extinction.”