Species have appeared and disappeared continuously throughout earth’s history,
with extinctions occurring at an average measure of 0.1 to 1 breed per million
species years. In several occasions, however, the rate has peaked sharply.
These were because of the five mass extinction events, mainly known as the end
of Ordovician- where 60 percent of all general of both terrestrial and marine
life went extinct, end of Devonian- where the environment with nurtured reefs
turned hostile and went extinct, end of Permian- where 80 to 95 percent of all
marine species went extinct, end of Triassic- where it was all marine
invertebrates and land quadrupeds that went extinct, and end-Cretaceous, which
was the extinction of dinosaurs, where it was due to the collision between
earth and an extraterrestrial bolide.
The sixth mass extinction, however, may now be happening- and the
apocalypse this time, is us.
Several different pieces of evidence suggest that earth is now
experiencing its sixth mass extinction. The ever growing human population-
which has increased by 130 percent in the last 50 years is expected to increase
to about more than 10 billion by 2060. With this, comes a hefty price- a great
deal of demand and pressure for resources on the natural world. (Johnston,
2017) Hundreds and thousands of species- mammals and birds included are being threatened
with extinction because of human behaviors. Some of the more terrible and
prominent ones are over-exploitation, poaching, pollution, loss of habitat and
the arrival of invasive species, which are more commonly known by using the
acronym HIPPO, are the primary drivers of this mass effect.
Habitat loss is one of the most widely known threats to all kinds of
species. Humans destroy the habitat by deforestation to clear land to make way
for agriculture and infrastructure- to build housing, roads, and other
developments. This, in turn, kills the animals that are living there and also
harms the habitat. Forests, lakes, swamps and different habitats are getting
taken down as they are being harvested for human consumption. One prime example
of this would be the destruction of habitat to clear land for palm oil plantations
in the tropical regions of Asia and many other countries. Vast tracts of
rainforests are being removed to grow palm oil crops. Figure 1 below shows the
forest cover vs the palm oil production in Indonesia- where there are fewer and
fewer spaces to clear for palm oil production.
Figure 1: Forest cover vs Palm Oil Production. Source: USDA, FAO
(Butler, R. 2012) Impact of industrial agriculture on rainforests.
Different species such as orangutans, tigers, elephants and rhinos are
significantly confined to a smaller and tighter space, and their sources of
food and shelter are in decline. Having no shelter, human-wildlife conflicts
are bound to happen because, without sufficient natural habitats, these species
come into contact with the human population and are often killed and captured.
When the species have no habitat to go back to, they slowly began to die and
become endangered, and this would likely lead to extinction in tropical
The emissions of toxic chemicals and heavy metals into the environment
has a huge and negative impact on species extinction. Even natural gases could
become toxic if they are in abundance. Pollution happens every day, and it is
far too less talked about. Pollution contaminates the environment and harms
species. For example, an oil spill would pollute the sea if it leaks from the
factories or industrial refinery. This discharge forms a thin layer of oil
called slick, which poisons the marine life and also traps the fur and feathers
of mammals. This not only kills the species, but it also scares the animals
away and they flee from the area, finding a new place to live. We can witness
this in lack of biodiversity in some cities.
Bioaccumulation is another factor that is also linked to pollution.
Chemicals from factories becomes increasingly concentrated inside the
tissues of the animal as they move up the food chain. Whales provide an
accurate example of bioaccumulation. Agricultural and industrial compounds are
present in organic pollutants. These pollutants are not harmful in low
concentrations. However, these contaminants are incorporated into organisms
like bacteria and other invertebrates at the bottom of the food chains. As
these organisms are eating fish, and marine mammals eat the fish, these
pollutants move up the food chain- meaning that over time, the concentration of
the contaminants continuously increases. These higher frequencies cause
disruptions to hormone levels and immune systems and increase congenital disabilities.
Next to habitat destruction, the growth of the human population is one
of the biggest threats to the environment. There isn’t enough room for the
natural environment to coexist with the human society, and also for land and
shelter. Therefore, in the rate of “survival of the fittest” animals and plants
get crushed under the skyscraper.
Figure 2: Human population over extinction. Source: Scott,
J.M. 2008. Threats to Biological Diversity: Global, Continental, Local. The
U.S. Geological Survey, Idaho Cooperative Fish and Wildlife, Research Unit,
University of Idaho
The human population annually absorbs about 42 percent of the earth’s
net primary productivity, 30 percent of its marine productivity and 50 percent
of its fresh water. The planet’s land is dedicated to human food production,
and about fifty percent of the earth land mass is being or has transformed for
human use. The figure below, from a U.S Geological Survey, shows us that as
human population increases, extinction of species increases as well.
Over exploitation is over-harvesting and over-hunting different species.
Humans hunt animals for their trophies either for their own use, or to sell
them to people for money. Animals like elephants are most hunted for their
trunks and are being sold to others for money. Figure 3 below shows the
elephant population that was in 1976 to 2013- which declined sharply because of
Figure 3: Elephant Population. Source: (Gordon, T. 2014) China denies
allegations of stripping ivory, slashing elephant population.
Ocean fisheries have been signed the most harvested species as compared
to others. The cod fishery in the Northwestern Atlantic Ocean was an essential
market for fishing for hundreds of years. However, the human population have
over-harvested these codfishes, and the community declined by over 90 percent-
where it will also lead to extinction if this continues.
One other example of over-harvesting is an extreme use of some critical
areas like wetlands and damaging them without knowing that these areas could
help many people. Most of the wetlands that people destroy by overusing them
could make drinking water for those people who do not have fresh water.
Sustained overexploitation could lead to the elimination of a resource- such as
fish stock and wild medicinal plants.
Invasive species is a species occurring, correspondingly because of
human activities, beyond its accepted normal distribution. It threatens
treasured environmental, agricultural and other social resources by the
catastrophic damages it causes. When an animal, or plant microbe moves into a
new area, it can affect the species living there in different ways. New species
can predate upon the species already living there and compete with them for
food and shelter. They can also carry with them, unfamiliar diseases and
disrupt the essential interactions.
An example of invasive species would be when rabbits were introduced to
Australia in 1859 for hunting. Rabbits bred way too quickly, as the environment
without any of their natural predators only made it more comfortable for them.
In less than a hundred years, there were close to about 600 million rabbits
across the entire continent. The rabbits took over the resources and habitats
of native species- like the bandicoot, which is now an endangered species. An
invasive species does not only have to be limited to animals. Plants could also
be in the category. One other example of an invasive species is the declared
weed species in Australia. They alter the natural environment which is purely
natural and destroy the habitat for native species. Some examples of these
invasive plant species are the mimosa and the alligator weed.
If there is one big lesson we can all take from this, it is that
ignorance is not bliss. Ignoring the cold hard facts that are being presented
to us would do more harm than good. Educating ourselves rather than turning a
blind eye and learning what is actually happening in the world would make us
all very much more aware of the harmful effects the planet has been having.
There is no doubt that the rate at which species are dying out is very high. A
change needs to happen- and how we respond to these problems are shaped by the
appeal of the solutions on offer. A difference in what mankind is doing is what
is required of this world.