Are we living through the seventh mass extinction event?

Mass extinctions…they are a bit like buses. You wait an epoch for one, then two come along at once.

Over the past 540 million years there have been five periods of species reduction so momentous they stand head and shoulders above the background extinction rate. They are, fabulously, called the ‘Big Five’. But, when does an ‘event’ become a ‘mass extinction’? At what point can we safely classify a reduction in species as being ‘mass’?

There is no real consensus on this – with many different geologists and palaeontologists suggesting different methods of analysis and consequently offering different interpretations of the wax and wane of speciation through the ages.

But despite the turmoil, Dr David Bond, the leader of an international team of researchers, thinks – buried in the folds of geological time – he has discovered another mass extinction. In a recent paper he suggests the Big Five budge-up and make room for a sixth member. The Capitanian event, which occurred approximately 262 million years ago.

Now, whether the scientific community embrace or shun this remains to be seen, but what is clear is that we are talking about past events here. This, I am aware, is a painfully obvious thing to say – but there is a reason I bother to do so.

It is Earth Day as I write this – something which should inspire the notion of change in us all. A notion that is strikingly pertinent in 2015. Later this year, a potentially landmark UN meeting to be held in Paris could be our ‘last chance’ to avert dangerous climate change. With bold action – including a commitment to create a zero-carbon society by 2050 – we could keep global warming below the all-important 2oC mark. Let’s hope an agreement is reached, but I have to confess – even if papers are signed and photo opportunities are taken – I remain deeply cynical over our species’ ability to tear itself from our oil addiction.

A few months ago I mentioned the growing acceptance, and even attempted formalisation, of the Anthopocene geological epoch. Our rapid species expansion and feverish consumption of natural resources has altered Earth’s geology to such an extent it has become definably different from its previous form.

Part of this of course is a change in biomass, and most experts now agree that human activities have accelerated the rate of species extinction, perhaps up to 1000 times the normal background rate. There is little doubt that if we still exist in millennia to come we will look back and recognise the Anthropocene as one of the biggest extinction events in our planet’s history. If that is the case, are we living through the seventh mass extinction event? Has the Big Five just become the Not-So-Magnificent Seven?

There is a certain alarming karmic symmetry to this – having created our own geological epoch, we now may be helpless to do anything other than end it with mass extinction.