Sixth mass extinction will be worse than previously thought, say scientists

Sixth mass extinction will be worse than previously thought, say scientists

Subject: Environment

Section: Biodiversity

Context:

• The planet’s sixth mass extinction, fuelled by human activities, may trigger a rapid biodiversity imbalance, according to scientists.

About the Study:

• The researchers analysed more than 71,000 animal species from five strata, including mammals, birds, reptiles, amphibians and insects and found that the next mass extinction will be worse than previously thought.
• The study offers the first comprehensive global scale picture of four categories of trends — decreasing, stable, increasing and species for which they remain unknown (for vertebrates and insects) — sourcing data from the International Union for Conservation of Nature (IUCN) Red List.
• Nearly 50 per cent of the animal population across all strata is being driven towards extinction.
• Mass extinction occurs when 75 per cent of the world’s species collapses in less than 2.8 million years.
• Study findings:
• The analysis portrayed a widespread global erosion of species, with 48 per cent undergoing declines, while 49 per cent remain stable and 3 percent of species currently increasing.
• Around 33 per cent of the species currently categorised as ‘non-threatened’ by the IUCN Red List show a declining trend. The declining population pattern indicates an imminent extinction.
• Extinction threat is particularly severe for amphibians compared to others and the decline was higher in the tropical regions than temperate.
• The mammals with declining populations were estimated to be 56 per cent.
• The insect population is dropping at a rate of 54 per cent, with just two per cent undergoing population growth.
• The researchers estimated that “around 40 percent of global species many become extinct in coming decades”.

What happens when species go extinct?

• Impact can be tangible such as in the form of a loss in crop pollination and water purification.
• If a species has a specific function in an ecosystem, the loss can lead to consequences for other species by impacting the food chain.
• Effects of extinction will worsen in the coming decades as the resulting genetic and cultural variability will change entire ecosystems.
• When the number of individuals in a population or species drops too low, its contributions to ecosystem functions and services become unimportant, its genetic variability and resilience are reduced, and its contribution to human welfare may be lost.

About the Mass Extinctions:

• 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.

Sixth mass extinction or Anthropocene extinction:

• Some researchers have pointed out that we are currently experiencing a sixth mass extinction as the result of human-induced climate change.
• More than 99 per cent of all organisms that have ever lived on Earth are extinct.
• As new species evolve to fit ever-changing ecological niches, older species fade away. But the rate of extinction is far from constant.