Species of animals and plants on Earth have appeared and disappeared since the beginning of time. In fact, only 2% of all the organisms that have ever existed on our planet still exist. But given that human activity is killing the natural environment at a rate that has not been done before, it isn’t a surprise that we may be experiencing yet another phase of extinction known as the sixth mass extinction.
Are We Facing a 6th Mass Extinction?
It is no news that humans are now witnessing immense effects on our environment, such as flooding, drought and as of late, huge fires.
Studies have shown that we have created these consequences. The destruction of nature has been taking place since the beginning of industrial production, where humans have utilized resources without replacing them.
In fact, over 70% of land resources and 75% of freshwater supplies have been used already.
The process of cultivating land has caused the fleeing of numerous species from their natural spaces, causing them to compete with us for resources and making themselves endangered.
5 Mass Extinctions Until Now
So far, we’ve had 5 mass extinctions that have altered life forms on Earth. Five great mass extinctions have changed the face of life on Earth. While it is known what caused a few of them, the origin of others is unknown to this day.
1. The Ordovician-Silurian mass extinction:
This event that killed 85% of all species took place over 443 million years ago, and is believed to have been caused due to declining temperatures that caused glaciers to overtake water, and decreasing sea levels. The resulting heat led to a number of small marine creatures to go extinct.
2. The Devonian mass extinction:
374 million years ago, eliminating 75% of all species, most predominantly water creatures. Given the presence of many environmental alterations such as global warming and cooling, an increase and decrease in sea levels as well as a reduction in oxygen and carbon dioxide in the atmosphere, the cause for the extinction is not known.
3. The Permian mass extinction:
250 million years ago, this event known as the Great Dying, eliminated more than 95% of all species, most importantly vertebrates. The reason for this is believed to be an asteroid that hit Earth, which filled the air with dust particles and blocked the Sun, leading to acid rain. Or, there was a volcanic explosion that brought upon carbon dioxide and toxified the waters.
4. The Triassic mass extinction:
200 million years ago, 80% of Earth’s species, including dinosaurs, were eliminated by colossal geological events that increased carbon dioxide levels and global warming, leading to water acidification.
5. The Cretaceous mass extinction:
65 million years ago, 78% of all species that included any surviving dinosaurs went extinct, thought to be caused by an asteroid hitting Earth at the spot of today’s Mexico, due to an ongoing flood volcano that took place in modern day India.
The Influence of Humans
Our actions of logging the Amazon rainforest is one of the leading causes of the extinction of numerous species.
As noted by the World Wildlife Fund, within the last five decades, 17% of the rainforest has been eradicated mostly due to the elimination of vegetation in order to create space for cattle ranching.This is crucial to understand because 80% of the world’s species can be found in tropical rainforests, including the Amazon. Deforestation taking place even in small spaces can lead to animal extinction, because they mainly live in isolated, out of reach areas.
As well as endangering animals, deforestation destroys tree cover that otherwise helps to catch atmospheric carbon dioxide. Since water absorbs 93% of the extra heat that greenhouse gases trap in Earth’s atmosphere, marine species and coral reefs are more prone to being eradicated.
According to studies, sea levels are increasing 40% faster than what was thought to be the case. The increase in acidified water then causes coral bleaching, where the algae living in corals turn white. This leads to coral reefs and the marine life forms they sustain to die. Until now, about 50% of the world’s reefs have diminished.
The Effects of Rising Sea Levels
The fact that oceans have warmed up has led to Arctic and Antarctic ice melting to an extent that hasn’t occurred before, leading to even higher sea levels. In the US, for example, 17% of the endangered species are at risk of going extinct because of rising sea levels.
The Antarctic ice is melting nearly six times as fast as it did in the 1980s, while Greenland’s ice is melting four times faster now than it was about a decade ago. In the worst imaginable scenario, known as a “pulse,” the glaciers carrying Antarctica’s and Greenland’s ice would collapse, sending immense amounts of ice into the oceans, that could in turn lead to incredible sea levels around the world.
According to a report from the Center for Biological Diversity, the threat of rising sea levels is very significant, endangering 233 animal and plant species in 23 coastal states across the US, including the Hawaiian monk seal and the loggerhead sea turtle.
Biological annihilation is a very current issue as half of the animal species that once existed with humans no longer do.
Some species are set to experience complete extinction, while local populations are disappearing in local areas. The latter is still a reason to be alarmed, as these localized extinctions act as a pavestone for whole species extinctions.
Insects are disappearing at increased rates as well, with 40% of the world’s insect species being endangered. The total mass of all insects on Earth is decreasing by 2.5% per year, which, if continued, will lead to the Earth not containing any insects at all by 2119. In addition, 500 amphibian species have been decreasing worldwide with 9- having gone extinct because of a deadly fungal disease that corrodes frog flesh. The development of this fungus has been aided by humans who have taken part in the global wildlife trade.
The Extinction Ripple Effect
When one species goes extinct, it can cause the entire community of an ecosystem to collapse. Studies have found that the extinction of one species can make more species vanish, in a chain of events known as co-extinction.
This is due to a sudden change in a system, such as a species of flower that could not live without its pollinator.
This is significant because co-extinctions tend to take place before the complete extinction of a species.
The Impact of Alien Species
Alien species can be a crucial factor in facilitating animal and plant extinctions. An alien species is any kind of animal, plant, fungus, or bacteria that doesn’t originate from a particular ecosystem. Some species are invasive, which means that they harm the environment in which they suddenly appear.
Humans have spread invasive species without necessarily meaning to, as they can carry alien species with them from one region to another easily while traveling or shipping goods.
A recent study has shown that since the year 1500, there have been 953 worldwide extinctions, with one third of them being a result of alien species being introduced.
It is evident that the last mass extinctions tended to come with signs that warned about them taking place, which aren’t unlike the ones we are witnessing now. Compared to past signs, today’s effects are alike but less serious for the time being.
Scientists, however, still argue about whether the Earth is actually experiencing the signs of another, or 6th, mass extinction. Some scholars believe that we’re not seeing that big of a threat, while others argue that by the time we have certain responses to that question, it isn’t impossible that three quarters of all the species in the world could go extinct.
If there is a definitive fact now, it is that humans are driving the main cause behind the risk of another mass extinction, so we should, as a collective, be paying attention to the signs around us before it’s too late.