Analysis Of Down To Earth Magazine: ”The 6th Mass Extinction!”
GS 3: Environmental Pollution & Degradation, Conservation
- Earth is losing species at an unprecedented rate, which, many believe, is the planet’s sixth mass extinction.
- Since the biodiversity loss this time is the doing of humans, the event also marks the beginning of the Anthropocene Epoch.
- The “Living Planet Report 2020” points out five major reasons behind the biodiversity loss across the planet: changes in land and sea use(habitat loss and degradation), overexploitation of species, invasive species and disease, pollution and climate change.
History Of Mass Extinctions
The Ordovician Era.
443 million years ago 85% of all species went extinct
Reasons: An “ice age” followed by a rapid warming.
The Devonian Age.
374 million years ago 75% of all species went extinct.
Reasons: Fluctuating sea levels, altering global cooling and warming, drop in CO2 concentration and periods of low oxygen.
The Permian Age.
250 million years ago 95% of all species went extinct
Reasons: An asteroid hit the planet, filling the air with pulverised particles, leading to inhabitable climate conditions.
- The Late Triassic Age.
- 200 million years ago 80% of all species went extinct
- Reasons: Some colossal geological activity in today’s the Atlantic Ocean that resulted in high CO2, global warming and acidified oceans.
- Cretaceous Period.
- 65 million years ago 76% of all species went extinct.
- Reasons: Meteor crash in the Yucatan peninsula in Mexico, high volcanic activity.
- The Holocene Epoch.
- About 99% of the planet’s species have been lost in the previous five mass extinctions Ongoing.
- Reasons: Anthropogenic factors like climate change and the introduction of invasive plant species.
What Worldwide Research Hints?
- The Global Assessment Report on Biodiversity and Ecosystem Services, the first such by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) released in 2019, shows that the current rate and scale of extinction is unprecedented and is being caused majorly by humans.
- The IUCN Red List now includes 142,577 species of which 40,084 (or 28 per cent) are under threat of extinction.
- The IPBES assessment says that 1 million animal and plant species face extinction and thousands of these would become extinct. Within decades about 40 per cent of the planet’s amphibian species are threatened with extinction. Since 1900, the number of native species in most land-based habitats has declined by 20 per cent.
- Since the year 1500, Earth could already have lost between 7.5 and 13% of the two million known species on Earth—a staggering 150,000 to 260,000 species.
The situation in Indo-Pacific Region
- Reports show the loss of vertebrate population was the highest in the Caribbean and Latin America (94 per cent), followed by Africa (65 per cent), with Europe and Central Asia showing the least loss (24 per cent).
- The World Wildlife Fund’s (WWF’s) “Living Planet Report 2020” says the Asia Pacific region lost 45 per cent of its vertebrate population in four-and-half decades, while the average global loss is 68 per cent.
- In the Asia Pacific region, including India that is experiencing loss of species higher than the global average, habitat degradation is the biggest trigger, followed by species overexploitation and invasive species and disease.
- The role of pollution and climate change was proportionately higher at 16 per cent.
- Loss of species afflicts all ecosystems—from land to oceans, from the sea surface to the yet-to-be-fully explored seafloors, from forests to desert, and from swamps to rivers.
- The loss could be higher than the global average in India, which has lost 12 per cent of its wild mammals, 19 per cent of its amphibians and 3 per cent of its birds over the past five decades.
- Of about 0.1 million animal species, as recorded in the country till December 2019, about 6,800 are vertebrates.
- Among these, nearly 550 fall in the critically endangered, endangered and vulnerable categories, according to the Zoological Survey of India, the country’s premier organisation in zoological research and studies under the Union Ministry of Environment, Forest and Climate Change.
- An assessment by the International Union for Conservation of Nature (IUCN) on dragonflies and damselflies revealed that 16% out of 6,016 species are at risk of extinction.
- The existential threat faced by dragonfly is a cause of concern for all of the planet’s 8.1 million species.
- With this assessment of the extinction of dragonflies, IUCN said, “the number of species at risk of extinction on the Red List has exceeded 40,000 for the first time.
- The fact that freshwater biodiversity is declining at twice the rate of that of terrestrial or marine species, is not just an alarming statistic for the environment, it is also highly concerning for people’s health and job security.
- Populations of migratory freshwater fish have fallen by 76 per cent since 1970 and large freshwater species, such as the catfish, by a catastrophic 94 per cent. Losing species at such an alarming rate has far-reaching consequences on the landmass.
Trees & Crops
- Over 70 wild relatives of some of the world’s most important crops are threatened with extinction.
- 35 per cent of wild species are on extinction mode.
- Without these trees, we will lose biodiversity altogether disabling us from evolving food crops varieties.
- Last year the Botanic Gardens Conservation International, a charity based in London, published its five-year assessment called “State of the World’s Trees”.
- The assessment evaluated 60,000 tree species and found that 30 per cent are at risk of extinction. Extinction in the plant kingdom is twice the number of threatened tree species globally than threatened mammals, birds, amphibians and reptiles combined.
- Over 440 tree species are on the brink of extinction, meaning they have fewer than 50 individuals remaining in the wild, the report reveals.
- In just the last three centuries, global forests areas have shrunk by 40 per cent.
- Every year, to meet the timber needs from natural sources, the Earth is stripped of 100 million trees.
- They store 50 per cent of the world’s terrestrial carbon and provide a buffer from extreme weather, such as hurricanes and tsunamis.