Nature is being killed at an exponentially fast pace due to adverse human activities. The consequences of such irresponsible actions have created a possibility of a 6th mass extinction.
Meaning Of Mass Extinction
Plants and animals are often seen disappearing from the planet and extinction is part of the process. It is believed that of all the organisms that existed on earth, 98% have already become extinct.
The extinct species normally get replaced by new forms of species in the ecosystem of the existing ones that fill their role. The ‘normal’ rate of extinction on earth is considered to range from 0.1 to 1 species for every 10,000 species in 100 years.
As a result, mass extinction refers to a much faster rate of disappearance of species while it is replaced slower. For instance, 75% of species all over the world become extinct within a short span of time, specifically in 2.8 million years.
Katie Collins, Benthic mollusks’ curator in the Museum, has informed that the beginning and end of a mass extinction cannot be identified easily. Nonetheless, 5 big events have been categorized when the extinction rate has been higher than the normal rate. In addition, the 6th impending mass extinction largely relies on these 5 past events.
Placenticeras was an ammonite that lived on earth simultaneously with the dinosaurs and became extinct. Their fossils are found across Northern and Southern America, Europe, and Asia. Triceratops was the last-known non-bird dinosaur that died during the Cretaceous- Palaeogene event almost 66 million years back.
5 Mass Extinctions In The Past
I: The Silurian-Ordovician mass extinction happened 443 million years ago. It wiped out nearly 85% of species. Scientists believe it occurred due to plummeting temperatures and the formation of large glaciers. This led to a dramatic decline in sea levels, followed by rapid warming. Numerous tiny marine animals became extinct.
II: The Devonian mass extinction occurred 374 million years back. It killed 3 quarters of the entire species population on earth, especially marine invertebrates which lived on the seabed. This period witnessed global cooling and warming, fluctuating sea levels along declining oxygen and CO2 in the atmosphere. The exact reason behind this event remains unknown.
III: The Permian mass extinction occurred 250 million years back. This is the biggest and most destructive extinction event and is often called the Great Dying. 95% of species were eradicated, including the newly-evolving vertebrates. Some scientists believe that a huge air-filled asteroid had hit earth and blocked the Sun, resulting in acid rain. Several others think a large volcanic explosion had amplified CO2 and caused toxicity in oceans.
IV: The Triassic mass extinction happened 200 million years back, killing 80% of species on earth, including several kinds of dinosaurs. A massive geological activity is believed to have increased global temperatures and CO2 levels. It also caused ocean acidification.
V: The Cretaceous mass extinction event happened 65 million years back, eradicating 78% of species on earth, including the existing non-avian dinosaurs. An asteroid is believed to have hit earth.
Causes Of Mass Extinction
Extreme temperature changes, catastrophic events like asteroid hitting or enormous volcanic eruption, and rise and fall in sea levels caused previous mass extinctions on earth. They have been identified through fossil records and intense study on the pattern of life on this planet.
For example, an important part of the work done by Katie explores fossils like bivalves to study extinction. According to her, bivalves are 500 million years old and this is greatly helpful in understanding the process of extinction. These oldest fossils offer good perpetual data acquired from across the globe.
Even though fossils give a good insight into the ways in which life traversed on the planet, there are still numerous unanswered questions. Katie has further added that the most studied mass extinction is the Cretaceous-Paleogene event that is the youngest. On the other hand, the cause and recovery remain grey areas for ongoing active research.
Oysters and clams are related to mollusks which create the bivalves. They usually remain buried under rocks, woods, or sediments for their entire lives. These filter-eating organisms fossilize after the sediments turn into rocks by becoming hardened.
Cause And Preventions For 6th Mass Extinction
The world is experiencing drastic environmental changes. From the time of the Industrial Revolution, human activities have greatly harmed the natural ecosystems and destroyed vast areas of forested land. 70% of the land cover has already transformed while 3-quarters of the freshwater is already being utilized.
Agriculture is causing soil degradation, pollution, loss of biodiversity, and deforestation. Countless animals are killed due to human greed. Wild spaces are becoming smaller that is forcing combat between humans and wildlife. Invasive species are threatening natural ecosystems increasing the probability of extinction.
Although mass extinctions take place over millions of years, at the present moment, we are witnessing the 6th one. Adverse human actions are certainly the biggest driving force. Climate change is resulting in wildfires and floods that have become more frequent in the past few decades.
Natural disasters will further aggravate existing inequalities. Research also shows that the rapid depletion of natural resources will have a crippling impact on future generations. Consequently, we must start rethinking the ways in which we interact with natural resources and change our approach towards land management.
Life on this planet is intricately interwoven and delicately balanced over years. Hence, the extinction of one species can easily collapse the entire ecosystem. The present extinction rate indicates the certainty of a 6th mass extinction.