Extinction: is it really that bad?
What are the real implications of mass species extinction, asks ecologist Euan Ritchie.
PERHAPS SOCIETY'S BIGGEST CHALLENGE, and arguably our largest failure, is the continuing loss of species from Earth.
The massive impact we are having on the planet has firmly entrenched us in a period of our history commonly called the Anthropocene, which refers to the evidence and extent of the impact of human activity.
We still have little idea of how many species exist on Earth. Only a fraction (somewhere around 1.5 million of an estimated 5 million) have been formally described, and even fewer assessed for their conservation status. How do we conserve what we don’t know exists?
If Earth were a house, it would be as though we had listed the contents of only one room, and even then were not aware of their true value, while simultaneously the house was being demolished.
Extinction a natural process
It is important to note that extinction, or the permanent loss of species, is a natural process that works in conjunction with speciation – the creation of new species through evolution.
“Normal” rates of extinction vary through time but are typically in the order of one to two species per year. Current rates of extinction, however, are estimated to have reached up to 10,000 times this rate. Put bluntly, the annual species body count is no longer a mere handful, it’s an avalanche.
There have been at least five episodes of mass extinctions in the past, during which anywhere from 60 to 96% of existing species became extinct. Indeed, 99% of all existing species that have ever existed are now extinct.
Volcanic eruptions and asteroid impacts are among the prime suspects as the cause of previous mass extinctions – including the oft-cited demise of the dinosaurs. Yes, mass extinctions are not unprecedented. The difference this time is that humanity is the cause of the earth’s sixth mass extinction event, through human-induced impacts such as habitat modification, the spread of invasive species and climate change.
Some 875 species have been recorded as declining to extinction between 1500 and 2009 which is entirely consistent with an extinction rate of 1-2 species per year. What, then, are the grounds for supposing that the current rate of extinction actually exceeds this value by such a huge margin?
The key phrase is “have been recorded”. As already discussed, the majority of species have not been identified or described. A reasonable supposition is that unrecognised species are lost at a rate comparable with that of known ones.
More recently we have bid farewell to species such as the Baiji Dolphin, the Alaotra Grebe and the Japanese River Otter. And who could forget the passing of “Lonesome George”, the last individual Pinta Island Tortoise? Closer to home, our most recent casualty was a small bat, the Christmas Island Pipistrelle.
An exclusive focus on extinction is inappropriate, given that many surviving species are hanging on only by the barest of threads. The dire situation of Australia’s marsupials is stark evidence of this. Even iconic and once abundant species such as the Tasmanian Devil are now on the brink of oblivion.
Why does extinction matter?
But why should it matter to us if we have a few less species? The simple answer is that we are connected to and deeply dependent on other species. From pollination of our crops by bees, to carbon storage by our forests, and even the bacteria in our mouths, we rely upon biodiversity for our very existence. We neglect this at our own peril.
Doom-and-gloom predictions tend to paralyse us, rather than jolting us into action. So what can be done? There are wonderful examples of individuals and organisations working at both small and large scales to tackle and even sometimes turn back the tide of extinctions.
But what is urgently needed, of course, is radical change in society as a whole in the way it interacts with its environment. Until then, my fellow ecologists and I must continue to work hard to sell our message and spread awareness of society’s biggest challenge.
Dr Euan Ritchie an ecologist at Deakin University in Melbourne. This is an edited version of an article first published on The Conversation.
The good fight: Captive breeding programs
Species loss almost twice as slow as thought
Mass extinction of lizards by 2080
Dinosaur extinction: more whimper than bang
Tasmanian tigers brought to life
Saving Australia's biodiversity
Species evolve slowly in arid Australia
Hidden populations of rare marsupial found
New method ranks species' extinction risk
Audio: Cross-fostering endangered species
Leadbeater's possum on the brink of extinction
Endangered species at risk from WA bushfires
GALLERY: The endangered animals of the Aussie Alps