We are generally quite reluctant to declare something extinct because detecting extinctions
it’s very difficult, you have to actually detect something not being there.
Extinction occurs when the last individual of a plant or animal species dies out.
Over 90% of anything that’s ever lived on Earth has gone extinct.
Depending on the figures you use, it could be as high as 99%.
New diseases, new predators or environmental changes can all lead to a species being wiped out.
When the earth loses a large proportion of its species
over a relatively short geological period of time,
it’s called a mass extinction event.
In the last 500 million years, there have been five of these.
The most prominent one, the one that most people are familiar with, is probably the
one that hailed the end of the dinosaurs.
That was 66 million years ago, when a giant asteroid struck the Earth.
That impact, mixed with large volcanic activity
and the resulting effects on the climate,
killed roughly half of all species on the planet.
But a mass extinction event can be caused by anything from rising global temperatures,
to volcanic eruptions to ice ages.
So should we expect another one?
There is some evidence that we are possibly on the verge of a sixth mass extinction,
and that is because over recent times we have seen quite a large of number of extinctions
in some of the better known species groups that we know much more about,
like the mammals, the birds, the amphibians.
So recent studies hint that we’re probably currently seeing a extinction rate that’s about
3-12 times higher, that’s a conservative estimate, other researchers say it’s even
much higher than that, it could be 80 times high, 100 times as high as background extinction rates.
The difference with the extinctions we’re seeing currently, as opposed to the ones that we’ve
seen over geological time, is that the main reasons for these extinctions are man made.
So we have had a most profound impact on our planet, we’ve become by far the dominant
species on this planet, and with this, have come a large number of threats to other species.
The human population, which has increased by 130% in the last 50 years, is due to surpass
10 billion by 2060. More and more people means the demand for resources will increase and
the pressure on the natural world will grow.
A mass extinction is likely to have happened at some point, because we’ve seen
over geological time that these events happen again and again,
some are bigger, some are smaller, some are some of the big five, for example,
and so yes, it could have, and is likely to have happened,
even without us being here and becoming the dominant species.
It’s just this is the first mass extinction that’s actually brought on by a specific species,
by one species dominating habitats.
We’re essentially looking at a situation where our life support system, our ecosystems
are in decline and starting to struggle to provide the functions that we would like them to give us
So, is there anything we can do to prevent another mass extinction event from occurring?
We absolutely can prevent it. So at the moment based on our best records, which are
those kept by the IUCN red list, on species extinction.
We actually have relatively few
extinctions recorded over the last five hundred years or so.
But what we can obviously see is that a large proportion of species are already kind of
getting close to extinction so about 25% of mammals are threatened with extinction.
40% of amphibians, for example. Probably around 1 in 5 reptiles and so on.
We’re essentially at a crossroad, we can totally prevent this,
it depends on whether we put the actions in place to stop species declines and species extinctions.
So whether or not we are in the midst of a mass extinction event,
it’s clear that the human race has a huge impact on the state of the planet we occupy.
For our future generations sake,
we need to seriously assess how huge that impact is.