Sixth mass extinction

Subject: Environment/geography

Context:

Sixth mass extinction of wildlife accelerating, scientists warn

Concept:

• 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 earlier 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.
• Further, attributing sixth mass extinction to humans, scientists said that one of the reasons that humanity is an “unprecedented threat” to many living organisms is because of their growing numbers.
• The loss of species has been occurring since human ancestors developed agriculture over 11,000 years ago. Since then, the human population has increased from about 1 million to 7.7 billion.