Editorial: End of an era, start of an error?

Mark Dawson

IT'S official! Or as official as anything can be after an international congress in South Africa has worked on it for seven years.

The Earth has entered a new epoch - an epoch being the term man gives to a slab of tens of millions of years usually distinguished by some particular geological trait.

We are now in the Anthropocene epoch, which means the timeframe when human activity is the dominant influencer on the planet. Humankind has ushered in an epoch for itself.

This week, at the International Geological Congress in Cape Town, it was announced by the working group set up in 2009 that the 11,700-year Holocene epoch is over - though there were no fireworks or singing of Auld Lang Syne. End of an era; start of an error, perhaps.

The idea of an epoch defined by human activity such as industrialisation and nuclear activity setting global systems on a different trajectory was first mooted in 2000.

Some would suggest that the recognition that we are changing the weather, melting the ice, raising the sea levels and possibly dismantling the complex and inter-dependent eco-systems that sustain life on Earth is long overdue.

The congress this week noted: "Changes to the Earth system that characterise the potential Anthropocene epoch include marked acceleration to rates of erosion and sedimentation; large-scale chemical perturbations to the cycles of carbon, nitrogen, phosphorus and other elements; the inception of significant change to global climate and sea level.

"Many of these are geologically long-lasting and some are effectively irreversible."

Elsewhere it was noted that "our epoch" had seen extinction rates of animals and plants soar, and we are now on course to see "75 per cent of species become extinct in the next few centuries".

What was it that pushed us over the edge and into the Anthropocene epoch? Many geologists point to the arrival of radioactive elements in rock strata (from nuclear testing in the 1950s), or the plastic now embedded in the Earth's shell for eternity. Some insiders say they are not yet ruling out that it was sparked by the collapse of the Whanganui wastewater plant.