SPECIES MASS EXTINCTION
Introduction:
The Global Ecosystem Assessment by Intergovernmental Science-policy Platform on Biodiversity and Ecosystem Services(IPBES) shows the current rate and scale of extinction, caused majorly by humans. The first Global Assessment Report on Biodiversity and Ecosystem services by IPBES rings alarm bells on the state of the planet’s biodiversity. It stated, that nature is declining globally at rates unprecedented in human history and the rate of species extinction is accelerating with grave impacts on people around the world.
According to a global assessment, one million animal and plant species are under extinction. Thousands of these would extinct within a decade.
Recent research said that 558 mammalian species get extinct by 2100 in Australia and the Caribbean.
Previous instances:
• At least 351 mammal species had gone extinct at the beginning of the Late Pleistocene 126,000 years ago,80 of which were known from historical reports since 1500 CE, while others are known from fossil or archaeological records.
• Research found that since the year 1500, the earth could have lost 7.5-13% of the 2million known species.
• 20% of native species of the land-based habitats,40% of amphibian species are threatened extinction in the last century.
• In the 16th century, 680 vertebrate species were pushed into extinction, from then on only 9% of all domesticated breeds of mammals are used for food and agriculture.1000 more breeds are under threat of extinction.
• Almost 33% of reef-forming corals and more than a third of all marine mammals are threatened.
• The earliest mass extinction, the Ordovician Extinction, took place when most of the life on the earth lived in seas.443 million years ago, 85% of all species went extinct because of an “ice age” followed by rapid warming.
• 2nd mass extinction or the Devonian mass extinction occurred 374 million years ago,75% of all species went extinct because of fluctuating sea levels, altering global cooling and warming, drop in CO2 concentration and periods of low oxygen.
• 3rd mass extinction or the Permian-Triassic Extinction happened 250 million years ago, 95% of the species went extinct. The reason was unclear, with the possibility of asteroids hitting and filling the air with pulverized particles, leading to inhabitable climate conditions.
• 4th extinction is The Late Triassic Age. It happened 200million years ago and 80% of all species went extinct. The reason behind this was the slow splitting of Pangea caused volcanoes to form the Central Atlantic Magmatic province. The result was high CO2, global warming and acidified oceans.
• 5th extinction happened around a 65million years ago in the Cretaceous Period. 76% of all species were extinct. The known reason was a meteor fall in the Yucatán peninsula of Mexico, causing high volcanic activity and release of high CO2 and killing half of the earth’s population.
• 6th extinction or the Holocene Epoch, killing 99% of the planet’s species. The known reasons are anthropogenic factors like climate change and the introduction of invasive plant species.
CURRENT SCENARIO:
According to the assessment, one million species of plants and animals are about to extinct.3/4th of the land-based environment and 2/3rd of the marine environment have been significantly altered by human activities. The decade is officially declared as the Anthropocene or the age of humans.
• Persistent pollution from chemicals, overfishing, and higher levels of CO2 in the atmosphere have degraded coastal and marine biodiversity.
• The Convention of Biological Diversity(CBD), which grew out of the epochal Rio Earth Summit of 1992, was established as a legally binding pact to arrest a precipitous decline in biodiversity.CBD brings together 193 Parties or signatories(192 nations and the European Union) and in 2002, it undertook to significantly reduce biodiversity loss in a decade.
• The World Wildlife Fund’s(WWF’s) “living planet report 2020” says the Asia Pacific region lost 45% of its vertebrate population in four and half decades, while the average global loss is 68%.
• Human population density, as a single predictor, explained mammalian extinction patterns with 96% accuracy. Climate predictors, led to low accuracy values like 60-63%.
• Ecosystems, species, wild populations, local varieties and breeds of domesticated plants and animals are shrinking, deteriorating or vanishing. This loss is a direct result of human activity.
• Up to 577$ billion in annual global crops are at risk from pollinator loss and 100-300 million people are at increased risk of floods and hurricanes because of the loss of coastal habitats and protection.
• An assessment by the International Union for Conservation of Nature (IUCN) on dragonflies and damselflies revealed that 16% out of 6016 species are at risk of extinction. This decline is due to rapid urbanization and the clearing of wetlands and rainforests to make way for cash crops.
• The IUCN Red List now includes 142,577 species of which 40,084(28%) are under threat of extinction.
Evolution and extinction are intimately linked to each other, but never before, it witnessed such a rapid change in biodiversity.
Future loss of species has the potential to reduce plant production just as much as global warming and pollution. In an ecosystem where 21 to 40% of the species go extinct, plant growth is expected to decrease by 5-10% an effect comparable to climate warming or increased UV radiation from stratospheric ozone loss. But at higher levels of extinction, the impact would be similar to acid deposition on forests, ozone pollution and nutrient pollution.
