Scientists believe life on Earth
is going through its sixth major mass extinction.
The cause?
Not a massive asteroid,
not an enormous flood.
But us
— humans.
A study from researchers at Brown University
shows that background extinction rates today
are 10 times worse than in previous mass extinctions.
Currently, there are more than 28,000 species at risk
of going extinct,
according to data from the IUCN Red List.
According to the Center for Biological Diversity,
99 percent of the species threatened today have
fallen victim to habitat loss,
the introduction of invasive species
into foreign habitats,
and of course,
climate change.
All of which are,
you guessed it,
human-driven phenomena.
Earth has witnessed five big mass extinctions so far,
the most famous of which is the fifth mass extinction
known as the K-T Mass Extinction,
you know
the one with the asteroid and all the dead dinosaurs?
It’s estimated that 75 percent
of all known species at the time
were wiped out.
Before humans, mass extinctions were triggered by
volcanic activity,
changes in ocean water composition,
continental drifts,
and climate change
— all of which arose due to natural environmental shifts.
So, if mass extinctions are a result of natural events,
why are we putting the blame on humans
this time around?
What exactly are the human activities driving species
to die out?
And are we really going through
the sixth mass extinction?
You’re watching Explore Mode and today,
we are going to dive into the human activities
that are destroying biodiversity on Earth,
causing what some scientists call
the Holocene extinction.
There are many reasons why scientists believe humans
are contributing to the rapid loss of
biodiversity on Earth,
but in this video,
we will focus on four:
Climate Change
Habitat destruction
Hunting by humans,
more specifically poaching and overfishing
And the disruption of ecosystems
through the introduction of foreign species
Let’s start with the big one:
Climate change.
Yes, Earth’s atmosphere naturally
traps greenhouse gases
therefore creating an overall
warming effect on the planet.
But since the industrial revolution,
human activity has disrupted
the natural creation of these gases.
According to a 2018 report
by the Intergovernmental Panel on Climate Change,
the world’s global surface air temperature
has increased by 1°C since the 1850s,
roughly around the time
when human industrialization began.
A one-degree increase in temperature
may not seem like much,
but to the delicate structure of life on Earth
it could mean the difference between life or death.
Oceans take the largest hit.
They absorb about 90 percent of the heat
of trapped greenhouse gases.
Additionally, the rise of CO2 presence in ocean waters
causes ocean acidification
which can lead to coral bleaching.
According to the IUCN Red List,
33 percent of reef corals are
threatened with extinction.
This leads us to mass extinction culprit number 2:
Human-driven habitat destruction.
Many consider this
the main cause of species extinction.
Forests cover 30 percent of the world’s surface area,
and they contain up to 80 percent of the world’s
terrestrial plant and animal species.
Sadly, human overconsumption and overpopulation
is decimating these habitats and
displacing the animals that live in them.
Humans have been burning and cutting down large
pieces of land in key biomes such as
the Amazons,
the Congo Basin,
and Indonesian rainforests to make
space for unsustainable agriculture,
logging,
mining,
dam building,
and cattle ranching.
According to the Rainforest Concern,
for each pound of beef produced,
200 square feet of rainforest are destroyed.
Not only does this destroy the habitat of many species
but it also exacerbates the effects of climate change
and greenhouse gas production.
One of the prime examples of how
human-driven habitat destruction
is decimating species
is the production of palm oil.
Time for an Express Explore Explanation.
Start the clock.
Palm oil is the most commonly produced vegetable oil.
Why?
It’s dirt cheap to produce compared to its sister oils
and very versatile in its use.
It can go into foods such as cookies,
frozen pizza,
and packaged bread,
or it can be used for chemical products such as
detergents,
lipsticks and
shampoo.
And in the EU it is the top vegetable oil
used as a biofuel alternative.
The problem is that it only grows in biodiverse tropical
rainforests, meaning large areas of rainforest have to be
cut down and burned down to develop palm plantations.
Around 85 percent of palm oil production happens in
Malaysia and Indonesia,
and on the island of Borneo alone at least half of
deforestation between the years 2005 and 2015
was due to palm oil production.
This is bad news for animals that
call these rainforests home.
The Sumatran orangutan, tiger and rhino are all critically
endangered species that are being displaced due to
palm oil production.
According to the latest data from the
World Wildlife Fund, there are only
80 Sumatran rhinos left,
and less than 400 Sumatran tigers left.
But burning forests aren’t the only threat to animals,
they’re also literally being hunted down by us...
Which leads us to poaching and overfishing.
Poaching is the act of illegal hunting or catching
of wild animals.
It’s a response to the demand for wild animal parts and
exotic animals, especially in black markets in Asia.
Wild tigers are poached for, essentially,
every single part of their body.
Traditional Chinese medicine consumers and
practitioners believe tiger teeth are good luck talismans
and, when ground, a remedy for rabies and asthma.
Tiger bones are also ground and put into pills which are
thought to treat low libido and arthritis.
Tigers that used to roam Java and Bali
have gone extinct.
The species is categorized as endangered with only
around 3,900 left,
some of which only survive in captivity.
Elephants are also poached, primarily for their tusks
which are sold to the ivory trade,
but also for their skin and even their genitalia which are
used to create jewelry and
other forms of Chinese medicine.
Sea turtles can be legally hunted and captured in
42 countries.
In the past 30 years,
2 million sea turtles have been killed for their eggs,
meat, and shells,
all of which are used for medicinal purposes.
And according to a report by the International Union for
the Conservation of Nature, due to overfishing,
more than 90 species of marine fishes in
European waters are threatened with extinction.
If you want to learn more about fishing and the effects
of fishing waste on animal life and
the marine environment,
check out the video we made on Ghost Gear,
where we cover some of these issues.
We’ll leave a link to it up here.
Finally, our last perpetrator of extinction
is the introduction of invasive species
to foreign environments.
Invasive species are any type of organism that lives in
an ecosystem that they are not indigenous to.
For example, Burmese pythons have become a pest in
the American Everglades.
How did these Southeast Asian snakes travel all the way
to America?
You know it,
humans.
Since humans started migrating we have carried all
types of pests, animals, and diseases with us.
Common invasive species are snails, rats, foxes,
feral cats, and snakes.
In fact, according to data from the IUCN Red List,
invasive species have been involved in
33.4 percent of animal species extinctions and
25.5 percent of plant species extinctions.
But how do these critters cause extinction?
Well, when invasive species are introduced into a
new environment, they may face no natural predators,
and native wildlife may not have evolved defenses
against them,
and so they multiply and take over resources of
local species,
driving native species into extinction.
Let’s take the example of the rosy wolf snail,
commonly known as the “cannibal snail”.
These were brought from mainland U.S. to islands in the
Pacific around the 1950s.
This invasive sluggard took over the Hawaiian
shrublands and caused the extinction of
eight types of native Hawaiian snails.
Humans also accidentally brought the brown tree snake
to Guam shortly after the Second World War.
This little blunder caused the loss of over 50 percent of
Guam’s bird and lizard species
and two of three native bat species.
One of the first species known to have gone extinct
due to human activity is the Dodo.
This three-foot three-inches tall flightless bird was
endemic to Mauritius, an island nation
in the Indian Ocean located east of Madagascar.
Two things led to the dodo’s downfall:
hunting, and invasive species.
See, dodos had never seen humans before,
and so they hadn’t evolved to fear us.
This made them extremely easy to hunt.
Around the 17th century, less than 50 humans
lived on the remote island, and yet,
they managed to introduce invasive species including
dogs, rats, cats, and long-tailed macaques that
attacked dodo nests for food while at the same time
decimating limited food resources.
By the late 17th century,
the dodo had gone completely extinct.
But it seems that centuries later,
there might be technologies in place that could bring
the dodo back from extinction.
In February 2018, researchers at Harvard University
managed to put together most of the genome of
a flightless New Zealand-native bird that went extinct
in the late 13th century called little bush moa.
They reconstructed its DNA using only the toe bone of
a piece in a museum.
Although they haven’t been able to successfully re-birth
the extinct bird,
this definitely brings us closer to a world
where de-extinction technology is a reality.
So are these scientists right to call this increase in
background extinction earth’s sixth mass extinction?
Some might say that’s debatable.
What’s not up for debate is that although humans only
make up 0.01 percent of life on earth,
we are heavily responsible for the lives of other living
beings on this planet.
Do you think we are doing a good job of
protecting them?
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