The Sixth Mass Extinction: Why Should We Care?

Written and verified by the biologist Cesar Paul Gonzalez Gonzalez

Last update: 24 August, 2023

Mass extinctions are long periods of time characterized by the sudden disappearance of many species. Although it’s true that this phenomenon is cyclical and has been repeated several times throughout history, it has a severe impact on the balance of the ecosystem. Moreover, its effects can be devastating and even threaten the existence of humans. So, what is the sixth mass extinction?

Unfortunately, several studies claim that we’re currently experiencing the so-called sixth mass extinction. However, not everyone is aware of the importance and seriousness of the issue. Therefore, in the following article, we want to address the main consequences, the origin, and some of the reasons why we should be concerned about this situation. Keep reading!

What’s a mass extinction?

Mass extinctions can be defined as a time interval in which species of a large number of taxonomic groups become extinct. According to an article published in the journal Current Biology, the losses amount to more than 75% of the total number of living beings, although this figure has been exceeded several times throughout history.

Mass extinctions often cause a “domino” effect.

As a result of the sudden loss of biodiversity, many other forms of marine, terrestrial, and aerial life begin to disappear. In other words, ecological instability is generated that harms other species, thus deepening the extinction event.

Although it’s a “sudden” phenomenon, mass extinctions have a duration measured in thousands or millions of years. Of course, this time span is “short” for on a geological time scale, but for living beings, they’re events of great extension.

What causes mass extinctions?

Mass extinction phenomena are caused by an enormous set of factors. In fact, different causes have triggered each of the events known to date, making it very difficult to establish a single origin. Even so, according to a study published in Greener Journal of Physical Sciences, the factors most associated with the occurrence of mass extinctions are the following:

• Global cooling: The reduction in global temperature causes species adapted to warm climates to be unable to survive in their environment. In addition, this situation is believed to be a triggering factor for glaciation and the decrease in ocean levels.
• Glaciation: The formation of large ice masses on the continents modifies the ecosystem and the availability of resources for living beings, causing their extinction.
• Decrease in ocean level: As the amount of frozen water increases, the sea level decreases, the physicochemical parameters of the water are affected and the available habitats are reduced. Therefore, it’s normal for marine biodiversity to decrease and for many species to disappear.
• Reduced availability of oxygen in the ocean: The changes that the ocean undergoes by reducing its level usually cause an increase in organic matter and facilitate the development of phytoplankton. Phytoplankton are capable of causing anoxia – conditions of low oxygen concentration – when their population increases dramatically.
• Volcanic eruptions: Smoke clouds released by active volcanoes can reduce the amount of sunlight hitting the earth. This deepens the reduction in global temperature and affects the survival of various plants. In addition, the ash that falls into the sea leads to the modification of marine ecosystems.
• Extraterrestrial phenomena: Those events or catastrophes that don’t originate on Earth, but come from outer space. The best example is the impact of an asteroid.

How many mass extinctions have there been?

As mentioned in the book La comunicación de la mitigación y la adaptación al Cambio Climático (The communication of mitigation and adaptation to climate change) at least 5 mass extinctions have been identified in the history of planet Earth:

1. Upper Ordovician (440 to 450 million years ago): Occurred due to a climate change that wiped out 25% of the species families that existed.
2. Upper Devonian (372 million years ago): Global warming and the reduction of oxygen in the ocean caused the loss of a little more than 19% of the taxonomic families of the time.
3. Permian-Triassic (250 million years ago): The causes of this extinction include climate change and the movement of tectonic plates. It’s estimated that more than 54% of the taxonomic families were lost.
4. Upper Triassic (almost 210 million years ago): Volcanic activity and global warming caused the extinction of about 23% of the existing families of species.
5. Cretaceous-Tertiary (65 to 66 million years ago): The main causal agent of this extinction was the impact of a meteorite. It’s estimated that 17% of the taxonomic families of the time were lost. The dinosaurs disappeared in this event.

The sixth mass extinction

In recent years, several specialists have suggested that the recent increase in the rate of species extinction is a sign of the beginning of the sixth mass extinction. However, an article published in the Biological Journal of the Linnean Society mentions that this may be unfounded, although it’s clear that there’s a problem with the loss of species.

Professionals who claim that we’re in the presence of a new mass extinction argue that this event is the result of human activities. In fact, as mentioned in a study in the journal Science Advances, extinction rates have been higher in recent years, with hundreds of vertebrates disappearing.

Although it’s not possible to say with certainty when the sixth mass extinction will begin, almost all specialists agree that ecosystems are under great pressure.

This means that there’s a profound imbalance in the functioning of food chains and their environment, which may lead to a large-scale loss of biodiversity.

If this “pressure” continues, some professionals estimate that between 6 and 10% of species will be lost by 2050, while by 2100, this percentage may increase to 27%. Of course, this is only a prediction. However, the real scenario may be much worse if action isn’t taken immediately.

What would cause the sixth mass extinction?

As indicated above, human activities are generally considered to be the main cause of the sixth mass extinction. Even so, other factors have been detected that seem to promote instability in ecosystems, as mentioned in an article in the journal Rendiconti Lincei. For example:

• Environmental pollution
• Climate change
• Destruction and fragmentation of natural habitats
• Introduction of exotic species
• Natural phenomena
• Meteorological phenomena
• Human overpopulation
• Overexploitation of natural resources

Why should we be concerned about the sixth mass extinction?

The massive loss of species has a detrimental effect on the environment, as it generates a phenomenon called coextinction, as suggested by a study by Biological Reviews.

In this regard, the disappearance of one species causes others to also be affected and be more likely to become extinct. Therefore, a domino effect is generated that ends up eliminating several inhabitants of our planet.

When a species disappears from the ecosystem, nature is capable of coping by using other members of the environment to compensate for its absence.

However, in the absence of several living beings, it’s normal for the balance to collapse and drastic changes to occur in the environment. Among them, the following stand out:

• Loss of biodiversity
• Modification of the environment
• Collapse of the food chain

The problem with this is that many mechanisms, such as the renewal of natural resources, local temperature control, and the recharging of aquifers, depend entirely on the stability of the ecosystem.

Consequently, with drastic events such as the sixth mass extinction, people will have difficulty obtaining food, drinking water, soils for production, and even clean air.

In other words, the current quality of life of humans is related to the stability of the ecosystem. The more the balance deteriorates, the more difficult it will be for people to meet their basic needs. Therefore, it’s crucial to avoid reaching this point.

Is it possible to stop the sixth mass extinction?

If the effects of a sixth mass extinction are to be avoided, it’s best to start repairing the damage caused by human activities. Among the actions that have been proposed to combat the negative effects of this phenomenon are the following:

• Reintroduction programs, guided by experts
• The generation of sustainable food production projects
• The development of clean energies
• The repair and recovery of damaged ecosystems
• Species conservation projects
• The reduction of carbon emissions
• Precise control of the exploitation of natural resources

Even if each of these proposals is carried out, we must be aware that it’s impossible to completely stop the negative impacts of mass extinction. In fact, we’re already experiencing several of its consequences, such as the reduction of crop production and the increase of eroded areas.

Reducing the damage could be the solution

Although it’s too late to avoid the extinction of many species, it’s crucial to try to reduce by all means possible the harmful impact of this phenomenon. In the end, it’s life on the planet that’s at risk, so these actions could be those which allow the human race to persist into the future.