All you need to know about the sixth mass extinction event

IE talks you through all you need to know about the sixth mass extinction on Earth- the first to result from human actions.
Sade Agard
Post apocalyptic city
Post apocalyptic city

breakermaximus/iStock 

  • Most conservation biologists today think humanity has already entered the sixth mass extinction phase due to the acceleration of species extinction.
  • The sixth mass extinction will be the first to result from human (anthropogenic) actions, including human-induced climate change.
  • Neanderthals, Denisovans, and Homo erectus all vanished. Homo sapiens could be next, but when?

Animals and plants go extinct all the time; it's a part of how Earth works. We know this because over the last 500 million years or so, since the origin of multicellular life, there have been at least five major extinction events. Each of these wiped out between 75 and 90 percent of the world's species at the time over a 'short' period of around 2.8 million years or less, and were brought on by dramatic but natural occurrences.

Most conservation biologists today think humanity has already entered a sixth mass extinction phase due to the acceleration of species extinction and biodiversity loss over the past 100 to 200 years. And guess what? Unlike past events, which were triggered by events such as impact from a 10-15 kilometer comet or increasing volcanism, this time, we may only have ourselves to blame.

In other words, the sixth mass extinction will be the first to result from human (anthropogenic) actions, including human-induced climate change.

What will be the 6th mass extinction?

All you need to know about the sixth mass extinction event
Overhunting of the dodo: a symbol of modern mass extinction

The next mass extinction will be arguably the sixth such event since multicellular life first appeared about 500 million years ago. This event will be the first since the end of the dinosaurs during the Cretaceous–Paleogene extinction event some 66 million years ago.

There is some debate as to whether we are still in the Holocene epoch - a geological division of time that began around 11,700 years ago, since the end of the last major glacial epoch, or ice age.

Some argue that humanity's profound impact on Earth may have induced a new epoch, called the Anthropocene epoch ('Anthro' means humans), which could have begun as recently as the 1800s during the Industrial Revolution.

All you need to know about the sixth mass extinction event
A sixth mass extinction could have begun as recently as the 1800s

As such, you may see that the sixth mass extinction is referred to as either the Holocene or Anthropocene mass extinction.

What will cause the next mass extinction?

All you need to know about the sixth mass extinction event
Various human-induced issues such as pollution are driving extinction rates

Unlike mass extinctions in the past, the sixth will be caused by people.

Both directly and indirectly, humans are contributing to the sixth mass extinction. These involve the spread of invasive species, habitat destruction, and illegal trade, and overexploitation of species, including overhunting.

Human-induced pollution, newly emerging illnesses, and climate change are also primary causes.

All you need to know about the sixth mass extinction event
Deforestation puts species at risk

A long-term threat is also posed by climate change. By injecting billions of tonnes of carbon dioxide (CO2) and other chemicals into the Earth's atmosphere each year, humans' use of fossil fuels has allowed us to mimic the release of huge quantities of greenhouse gases from volcanism, in regions geologists call large igneous province.

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Vast igneous provinces, such as the Central Atlantic Magmatic Province, in the supercontinent of Pangaea, are thought to have been the source of volcanic action that led to previous mass extinctions, including The Permian-Triassic mass extinction 252 million years ago and the Triassic-Jurassic mass extinction 201 million years ago.

All you need to know about the sixth mass extinction event
Extent of CO2- and methane-releasing Siberian traps (In German)

According to an article by National Geographic, these ancient volcanic regions produced significantly more carbon dioxide than people do now. For example, the Siberian Traps igneous province is thought to have produced more than 1,400 times as much CO2 in total as was produced in 2018 through burning fossil fuels for energy.

Still, overall, humans are producing greenhouse gases at a rate equal to or greater than that released by the Siberian Traps. As a result, the planet's climate is changing very quickly, triggering terrestrial and marine extinctions.

Is the 6th mass extinction happening now?

According to one popular theory, the sixth major extinction catastrophe has been happening for around the past 10,000 years, starting at the end of the last ice age. However, a growing human population and a warming planet have exacerbated the speed of this global extinction.

Even while we're still a long way from the 75 percent threshold, the current extinction rate of species is estimated at 100 to 1,000 times higher than natural background extinction rates. This is only set to increase as the human population grows.

"What we've lost in 100 years would have been lost in 10,000 years in normal times," said Gerardo Ceballosceballos, an ecologist at The National Autonomous University of Mexico.

Currently, 60 percent of primate species are in danger of extinction due to human activity, and 75 percent of primate species have declining population sizes.

The way we deplete natural resources without helping them to recover has been most significant- especially since the industrial revolution, which began in the 1800s.

All you need to know about the sixth mass extinction event
There are currently about 880 mountain gorillas left in the world

The planet is currently facing a biodiversity crisis. According to a report issued by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) back in 2019, of an estimated 8 million animal and plant species, around 1 million are currently threatened with extinction.

This is mainly due to human activities like deforestation, pollution, hunting, diversion of water resources, and overfishing. Invasive species and diseases that spread through human trade, pollution, and climate change are all serious threats to life as we know it.

Moreover, the populations of vertebrate species have severely declined since the 1970s by about 68 percent. Currently, more than 41,000 species are considered under threat of extinction by the International Union for Conservation of Nature (IUCN).

All you need to know about the sixth mass extinction event
The Great Barrier Reef has lost half of its corals since 1995

Ocean warming, acidity, and climate change are harming corals. In fact, some scientists have already estimated that by the year 2100, there may be almost no coral reef habitats left in any ocean on Earth. As revealed by previous mass extinctions, sudden climate change can be hugely destructive.

The extinction of at least 680 vertebrate species, including the dodo, Steller's sea cow, Tasmanian wolf, and great auk, is said to have been brought on by humans. Those species will probably not be the last to become extinct due to human activity.

Still, whether all of this truly meets the criteria for another mass extinction remains hotly debated.

How long will the 6th mass extinction last?

At least 75 percent of all species perished within 2.8 million years or less during each of the last five mass extinctions. According to some scientists, if we continue along our current course, we might be able to lose that number within just a few centuries.  

We might reach mass extinction in as little as 240 to 540 years if all species currently listed as severely endangered, endangered, or vulnerable go extinct within the next century. This assumes that the current rate of extinction continues without slowing down.

Because ecosystems are so complex, attempting to forecast the outcomes, including how long a mass extinction will last, is not possible. 

Still, one conclusion of a new study states that three-quarters of today's animal species could vanish within 300 years.

Could Earth be experiencing a 7th - not a 6th - mass extinction event?

All you need to know about the sixth mass extinction event
Dickinsonia, extinct, multicellular creatures of the Ediacaran era

New research suggests a mass extinction event may have occurred millions of years earlier than scientists previously realized. A recent Interesting Engineering (IE) article highlighted that 80 percent of species existing at the end of the Ediacaran Period (nearly 550 million years ago) became extinct due to a drop in oxygen availability worldwide.

Should this be the case, the next mass extinction event will be the seventh, not the sixth. Still, in our defense, we did note earlier that we were discussing mass extinctions within the last 500 million years (five, in this case, would still be correct). In addition, there have been a number of events where extinctions rise well above background levels without reaching the scale of one of the five or six major mass extinctions. These are sometimes called minor mass extinctions.

Could humans survive the sixth mass extinction?

All you need to know about the sixth mass extinction event
Homo sapiens are widespread- we may be sticking around for a while

The fossil record shows us that everything goes extinct eventually. Almost all species that ever lived, over 99.9 percent, are extinct. Some left descendants. Most—plesiosaurs, trilobites, Brontosauri—didn't.

That's also true of other hominid species. Neanderthals, Denisovans, and Homo erectus all vanished, leaving just Homo sapiens. Still, It is inevitable that Homo sapiens will go extinct too. The only question left to be resolved is when- and this doesn't necessarily mean during the sixth (or seventh) mass extinction.

That said, humans are also highly adaptable—possibly even uniquely so. Unlike pandas and polar bears, which occupy ecological niches, humans are widespread and abundant, suggesting that we will continue to exist even after a mass extinction wipes out many other species.

Think, if one of our habitats is destroyed, humans elsewhere can survive in another. Put simply, our eggs aren't all in one basket.

However, as Elizabeth Kolbert, author of the book 'The Sixth Extinction," put it, "Even if we can survive, is that the world you want to live in? Is that the world you want all future generations of humans to live in?"