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Current Affairs

Sixth mass extinction

Date: 03 June 2020 Tags: Miscellaneous

Issue

The ongoing sixth mass extinction may be one of the most serious environmental threats to the persistence of civilisation, according to new research.

 

Background

Even though only an estimated 2% of all of the species that ever lived are alive today, the absolute number of species is greater now than ever before. 

 

Details

  • Mass extinction refers to a substantial increase in the degree of extinction or when the Earth loses more than three-quarters of its species in a geologically short period of time.

  • So far, during the entire history of the Earth, there have been five mass extinctions. The sixth, which is ongoing, is referred to as the Anthropocene extinction.

  • The five mass extinctions that took place in the last 450 million years have led to the destruction of 70-95 per cent of the species of plants, animals and microorganisms that existed earlier.

  • These extinctions were caused by “catastrophic alterations” to the environment, such as massive volcanic eruptions, depletion of oceanic oxygen or collision with an asteroid.

  • After each of these extinctions, it took millions of years to regain species comparable to those that existed before the event.

  • The study analysed 29,400 species of terrestrial vertebrates and determined which of these are on the brink of extinction because they have fewer than 1,000 individuals.

  • Out of the studied species, they concluded that over 515 of them are near extinction, and that the current loss of species, which is based on the disappearance of their component populations, has been occurring since the 1800s.

  • Most of these 515 species are from South America (30 per cent), followed by Oceania (21 per cent), Asia (21 percent) and Africa (16 percent) among others.

  • The study notes that more than 400 vertebrate species went extinct in the last century, extinctions that would have taken over 10,000 years in the normal course of evolution.

  • When species go extinct, the impact can be tangible such as in the form of a loss in crop pollination and water purification. Further, if a species has a specific function in an ecosystem, the loss can lead to consequences for other species by impacting the food chain.