Sixth Mass Extinction Induced by Human
Top Current Affairs 11th June 2020
Source | Indian Express
GS Paper III: Conservation.
- 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, the Earth has experienced five mass extinctions.
- It has been observed that the sixth extinction is human-caused and is more immediate than climate destruction.
Context: Recently, the researchers have observed that the ongoing sixth mass extinction is one of the most serious environmental threats to the existence of civilisation.
What you need to know about Mass Extinction from UPSC Point of View?
- What is Mass Extinction? : 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. Since life first evolved on the planet, a short geological period of time is defined as less than 2.8 million years.
- How many Mass Extinctions has taken place so far? So far, the Earth has experienced five mass extinctions.
Also Read: HEAT WAVES | What You should know?
|Era||Impact and Possible Reasons|
|First Mass Extinction: End Ordovician, 444 million years ago||86% of species lostSevere ice age that lowered sea levels, possibly triggered by the uplift of the Appalachians. The newly exposed silicate rock sucked CO2 out of the atmosphere, chilling the planet.|
|Second Mass Extinction: Late Devonian, 383-359 million years ago||75% of species lostWith the emergence of land plants, their deep roots stirred up the earth, releasing nutrients into the ocean. This might have triggered algal blooms which sucked oxygen out of the water, suffocating bottom dwellers like the trilobites.|
|Third Mass Extinction: End Permian, 252 million years ago||96% of species lostA cataclysmic eruption near Siberia blasted CO2 into the atmosphere. Methanogenic bacteria responded by belching out methane, a potent greenhouse gas. Global temperatures surged while oceans acidified and stagnated, belching poisonous hydrogen sulfide.|
|Fourth Mass Extinction: End Triassic, 201 million years ago||80% of species lostNo clear causes have been found.|
|Fifth Mass Extinction: End Cretaceous, 66 million years ago||76% of all species lostVolcanic activity and climate change along with asteroid species|
What does the study says about the Sixth Mass Edition? : It has been observed that the sixth extinction is human-caused and is more immediate than climate destruction. Thus, the ongoing sixth mass extinction is referred to as the anthropocene extinction. Currently, only an estimated 2% of all of the species that ever lived are alive but the absolute number of species is greater than ever before.
- It is described as the most serious environmental problem since the loss of species will be permanent.
- 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.
- The study analysed 29,400 species of terrestrial vertebrates and concluded that over 515 of them are near extinction.
- Most of these 515 species are from South America (30%), followed by Oceania (21%), Asia (21%) and Africa (16%) among others.
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