By: Elise Gilchrist
Over the
years I have met many a debate when I inevitably start spewing alarming facts
and statistics about mankind’s impact on our world. This began when I became
fascinated by extinction rates and how rapidly our planet was losing its species.
The argument I always encountered from the opposition was that the Earth is
resilient, loss of species is a natural occurrence, and ecosystems have adapted
around the loss. “It’s just natural selection at work!” they would say. Unfortunately that argument often rooted me
upset and without rebuttal.
Fueled by
my intense interest in conservation and wildlife, I have since become better
informed about the planet’s history of mass extinction. A mass extinction is
defined as a relatively short geological time interval in which three-quarters
or more of the Earth’s species went extinct. Since the beginning of life on
Earth there have been five mass extinctions. The most famous of these is the
most recent, occurring 65 million years ago that wiped out the last of the
dinosaurs. Each one of these mass extinctions has been characterized by
extremely widespread species loss and physical causes (i.e. giant meteors
striking the planet).
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| An extinct wooly mammal, a species related to the elephants of today. |
So, how
does this at all relate to my previous story of getting schooled in arguments
about the environment? The answer lies in the theory that we are currently
within or at the start of a sixth mass extinction!
I will concede to my aforementioned opponents
that extinction is natural and that the Earth has proven to be rather
resilient. The background extinction rate,
or the rate at which plants and animals have historically gone extinct, is
estimated to be less than two species per million years (Barnosky et al. 2011).
However, some current estimates put extinctions at two per hour. If I could go
back in time, I would explain to my argumentative peers that previous
extinctions occurred less frequently than they do today, and those in the past were
also counteracted by speciation, the
creation of new species. Unfortunately, this important balance has not been
maintained in more recent history, and more species are going extinct than are
forming.
But besides
its accelerated rate, what makes this mass extinction different from the rest,
besides the accelerated rate? The answer is human activity. All previous mass extinctions
occurred from physical forces, whereas the one we are experiencing now is from
a biotic cause. Diagnosis: Homo sapiens.
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| An Asian elephant, named Poonlarb, who lives here in the Golden Triangle of Thailand. |
Even though the rates of extinction
we are seeing today are alarming, only 1-2% of all species have gone extinct in
recent times. This means that there is still a lot of biodiversity left to save
if the global community is willing to make some changes. Think Elephants
International (TEI) is currently working to save one of the species at the
brink of extinction, the Asian elephant. By conducting research on this species
in a controlled manner, the conservation community as a whole will be better
equipped to mitigate the problems Asian elephants face today. TEI is also
working to establish conservation education curriculums to better inform
tomorrow’s government officials, community leaders, and consumers about how to
best protect the biodiversity of the future. The question is, are you willing
to help?
Barnosky, A. D. et al. (2011) Has the Earth’s sixth mass
extinction already arrived? Nature 471, 51-57.
http://commons.wikimedia.org/wiki/File:Wooly_Mammoth-RBC.jpg
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