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Act now to prevent sixth mass extinction

Last Updated 16 July 2017, 18:14 IST

Scientists have recorded five mass extinctions when the diversity of life on earth suddenly and dramatically contracted over the last half a billion years. According to a recent study published in the Proceedings of the National Academy of Sciences, “biological annihilation” of wildlife in recent decades indicates that the sixth mass extinction in earth’s history is underway and is more severe than previously feared. Given that the fifth extinction recorded 65 million years ago, when a giant asteroid impact on Mexico, just after large volcanic eruptions in what is now India, saw the end of the dinosaurs, this may appear alarmist. Gerardo Ceballos, an ecology professor at the Universidad Nacional Autónoma de México, and his co-authors, including well-known Stanford University biologist Paul Ehrlich, however, cite striking new evidence that populations of species we thought were common are suffering in unseen ways to justify their prediction.

Analysing both common and rare species, they have found that billions of regional or local populations have been lost, more than half of them in recent decades. Previous studies have shown that species are becoming extinct at a significantly faster rate than for millions of years before, but gave the impression of a gradual loss of biodiversity. The new work, instead, takes a broader view. According to the authors, billions of populations of mammals, birds, reptiles and amphibians have been lost all over the planet. Looking at a well-studied group of 177 mammal species, they found that all of them had lost at least 30% of their territory between 1900 and 2015 and more than 40% of those species “experienced severe population declines”, meaning they lost at least 80% of their geographic range during that time.

One need not be a scientist to know that human population growth and the accompanying increase in human consumption are the root cause of the mass extinction of species we are currently witnessing. The human population has grown so large that roughly 40% of the earth’s land surface is now farmed to feed people — and none too well at that. It will require a drastic reduction in the human fertility rate and a change in the consumerist culture to reverse the process. Unfortunately, as the study shows, the window of opportunity for corrective action is very shot. The world has only 20-30 years at most to tackle the crisis. It will take a long time to humanely stop that growth and start the gradual shrinkage of the human population that is required if the human civilisation is to persist. The time to act is now or never.

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(Published 16 July 2017, 18:13 IST)

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