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UPSC Prelims 2018 · Environment · Warming World
The term "sixth mass extinction/sixth extinction" is often mentioned in the news in the context of the discussion of
- (a) Widespread monoculture practices in agriculture and large-scale commercial farming with indiscriminate use of chemicals in many parts of the world that may result in the loss of good native ecosystems.
- (b) Fears of a possible collision of a meteorite with the Earth in the near future in the manner it happened 65 million years ago that caused the mass extinction of many species including those of dinosaurs.
- (c) Large scale cultivation of genetically modified crops in many parts of the world and promoting their cultivation in other parts of the world which may cause the disappearance of good native crop plants and the loss of food biodiversity.
- (d) Mankind's over-exploitation/misuse of natural resources, fragmentation/loss of natural habitats, destruction of ecosystems, pollution and global climate change.
Show the answer and explanation
Answer: (d) Mankind's over-exploitation/misuse of natural resources, fragmentation/loss of natural habitats, destruction of ecosystems, pollution and global climate change.
The sixth extinction is the current loss of species driven by human over-use, habitat loss, pollution and climate change.
The idea
A mass extinction is the loss of about three-quarters of all species in a short span of geological time. It has happened five times, each time from a natural cause. Scientists call the present loss the sixth because the rate is again far above normal, and this time the cause is one species: humans.
1. End-Ordovician → 2. Late Devonian → 3. End-Permian, the largest (“Great Dying”) → 4. End-Triassic → 5. End-Cretaceous, 66 million years ago (dinosaurs) → 6. Now: caused by humans
Why the others are wrong
(a) Monoculture is one pressure, but too narrow.
(b) The fifth extinction (dinosaurs) was a meteorite; the sixth is not about space rocks.
The trap
(b) borrows the fifth extinction’s cause.
Also know
Species are now being lost at an estimated 100 to 1,000 times the natural background rate. The 2019 IPBES global assessment said about one million species face extinction. The five main causes it lists: change in land and sea use, direct exploitation, climate change, pollution and invasive species. The proposed name for the human age is the Anthropocene.
🔒 5 past mass extinctions (last: 66 Mya, asteroid). The 6th = the Anthropocene extinction.