Sixth mass extinction
18th Jun, 2020
According to new research published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), the ongoing sixth mass extinction may be one of the most serious environmental threats to the persistence of civilisation.
- The ongoing sixth mass extinction may be the most serious environmental threat to the persistence of civilization, because it is irreversible.
- Thousands of populations of critically endangered vertebrate animal species have been lost in a century, indicating that the sixth mass extinction is human caused and accelerating.
- The acceleration of the extinction crisis is certain because of the still fast growth in human numbers and consumption rates.
- In addition, species are links in ecosystems, and, as they fall out, the species they interact with are likely to go also.
- In the regions where disappearing species are concentrated, regional biodiversity collapses are likely occurring.
Understanding the mass extinction of species:
- 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.
- Five mass extinctions: So far, during the entire history of the Earth, there have been five mass extinctions.
- 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 sixth, which is ongoing, is referred to as the Anthropocene extinction
The sixth extinction
- Researchers have described it as the “most serious environmental problem” since the loss of species will be permanent.
- 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, researchers concluded-
- over 515 of them are near extinction
- 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.
- of the 515 species, forest owlet in Central India, Nilgiri marten (Western Ghats), Bugun liocichla (Arunachal Pradesh), Bengal florican (Assam), great Indian bustard (northwest India), white-winged wood duck (northeast India) will disappear soon.
- the current loss of species has been occurring since the 1800s.
- 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.
- In a sample of 177 species of large mammals, most lost more than 80 per cent of their geographic range in the last 100 years, and as per a 2017 study published in the same journal, 32 per cent of over 27,000 vertebrate species have declining populations.
- Among those facing extinction, 243 (47%) are continental and 272 (53%) insular (island-dwelling). Most of them are from South America, followed by Oceania, Asia, Africa, North and Central America, and then Europe with less than 1% of them.
- The greatest numbers of mammals on the brink extinction are in Asia and Oceania. Most such birds live in South America and Oceania.
- The distribution of species on the brink extinction shows they also include those in the biodiversity hotspots of the Himalayas and the Western Ghats.
What’s leading to the extinction?
In contrast to the Big Five, today's species losses are driven by a mix of direct and indirect human activities, such as the destruction and fragmentation of habitats, direct exploitation like fishing and hunting, chemical pollution, invasive species, and human-caused global warming.
- Uncontrolled human population: 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.
- Overexploitation of resources: Human overpopulation, combined with a great need for resources and our growing impact on the environment. The progressive disappearance of species is mainly down to two factors:
- Overexploitation of natural resources(deforestation, hunting and fishing, etc.)
- An economy based on fossil fuels (that pollute the atmosphere) and are producing global warming with dire consequences for ecosystems.
How will it impact India?
- The species are on the verge of extinction which will also lead to larger collapses. In India this is specially pertinent as the country have species that are naturally or historically low in number. And a wide range of factors are interacting with them.
- Several Indian species are mentioned in the paper.
- The Kolar-leaf nosed bat, named in this paper is found in only one cave in Kolar. If the stigma against bats due to fake covid spreads, the entire population could be made extinct.
- And the Great Indian Bustard is threatened by increasing transmission lines in Kutch, Gujarat.
- The White-bellied Heron has less than ten known individuals in India and its habitat is threatened by submergence by proposed dams like Demwe in Arunchal Pradesh.
- National Autonomous University of Mexico and Stanford University scientists led the analysis based on the IUCN Red List of Threatened Species and Birdlife International database. The analysis said in view of the current extinction crisis and the lack of widespread actions to halt it, it is very important that scientists “should metaphorically take to the streets”. This is because the current mass extinction
What after extinction?
- Loss in crop pollination & water purification: When species go extinct, the impact can be tangible such as in the form of a loss in crop pollination and water purification.
- Impacting the food chain: 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.
- The 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 is reduced, and its contribution to human welfare may be lost.
- Humanity would be deprived of many of biodiversity’s benefits, much of which make life on Earth possible.
- Complete ban on wildlife trade: Significantly, the study calls for a complete ban on wildlife trade as many of the species currently endangered or on the brink of extinction are being decimated by legal and illegal wildlife trade.
The current COVID-19 pandemic, while not fully understood, is also linked to the wildlife trade. “There is no doubt, for example, that there will be more pandemics if we continue destroying habitats and trading wildlife for human consumption as food and traditional medicines.”