According to recent studies, plants and animals are becoming extinct at least 1000 times faster than before humans arrived on the scene, suggesting that we may be heading towards the sixth great extinction.
Scientists used to believe that the past rates of extinction were a lot higher making a comparison with present day extinction rates less stark. However, recent studies by Duke University are suggesting that past rates of extinction may have been much lower than previously believed while present day extinction rates appear to be around 10 times higher than what was believed.
In light of these facts, biologist Stuart Pimm of Duke University has stated that "We are on the verge of the sixth extinction….. Whether we avoid it or not will depend on our actions”
His work, now published by the Journal of Science, received huge acclaim from the scientific community. In it, he focuses on the rate by which species are becoming extinct rather than on the total number of species. He calls this figure the “death rate” which is measured by the number of species that become extinct each year out of 1 million species.
Back in 1995, Pimm determined that the prehumen rate of extinction was around 1 but in light of these new findings, he ascribes this value to about 0.1 which is an order of magnitude lower than his initial belief.
Putting the significance of this issue into perspective, the death rate today is around 100 to 1000.
According to the Institute of Ecological Research in Brazil, there are many reasons for this dramatic increase in death rate but the main contributing factor is habitat loss. As people keep expanding and moving into natural habitat, animals are being displaced. Those that have specific habit requirements are unable to cope in the new environment while others are crowded out by native species causing them to disappear.
One prime example of this can be seen in the case of the buffy-tufted-ear marmoset where humans took over part of their natural habitat and a competing marmoset species taking over what remains causing the buffy-tufted-ear marmoset to fall into the international vulnerable list.
Another similar example is the case of the white-tip shark which at one time was amongst the most abundant predators on earth but have since been hunted so much that they are rarely ever seen these days. No one sums this up better than Boris Worm a marine biologist of the Dalhousie who stated that, "If we don't do anything, this will go the way of the dinosaurs."
As alluded to in the beginning, if we are heading towards the 6th great extinction, this would not be the first time it has happened. In the other five times prior to this, mass extinctions have often been associated with meteor strikes. One notable instance being the great extinction of dinosaurs 66 million years ago which killed off the dinosaurs as well as ¾ of every species on earth. Another more devastating extinction was the Great Dying 252 million years ago which killed over 90 percent of the world’s species.
While scientific studies paint a dark picture, there is still hope. According to Pimm and Jenkins, the use of smartphones and applications like iNaturalist can help normal people and biologist to identify species that are in danger. In doing so, they could raise awareness and allow biologist to save these species using captive breeding and other techniques.
One notable example of this is the success story of the golden lion tamarin. Decades ago it was believed that this species was extinct due to habitat loss but luckily one was found in the remote parts of Brazil and was bred in captivity. Today biologist have set aside a new forest for them to live in and according to Jenkins, “Now there are more tamarins than there are places to put them".
So….Are we on the brink of the sixth extinction? It’s up to you…..
Written by: Sukree Sachamuniwongse
Journal Science: http://www.sciencemag.org