The greatest transitions in the geological timescale are marked by the flowering or decimation of life. With species extinction and global warming gaining speed, humanity’s impact on Earth is clear

The events marking a new geological chapter in the Earth’s history need to be epoch making – literally. So whether a new epoch – the Anthropocene – should be formally declared is a question of whether humanity’s impact on our planet rivals the great events that have shaped the Earth’s evolution. The answer is a terrifying yes.



It’s a mistake to think that the geological timescale is simply about rocks. Almost all its great ruptures are marked by the flowering or decimation of life. Living creatures and their fossils are the markers of geological time. The greatest transition began 540m years ago, when complex, multicellular life evolved in response to the rise of oxygen in the atmosphere. Eighty million years later, at the start of the Carboniferous, the first land plants bloomed.

Those lush forests are the source of the coal, oil and gas that humanity is now burning in vast quantities, ushering in a new change in the global atmosphere. The concentration of climate-warming carbon dioxide is now higher than at any time since the dawn of humans 2.6m years ago, an event itself marked by a new geological epoch called the Pleistocene.

Titanic ruptures in the geological timescale are also marked by the great extinctions. The greatest of all was 250m years ago at the end of the Permian period, when 96% of all species were wiped out. The most famous great extinction ended the tyranny of the dinosaurs 66 million years ago, opening the evolutionary door to mammals including, eventually, us. Today species are going extinct at rates not seen since that time and a new great extinction is under way. Previous wipeouts took millions of years, but half of all wildlife on Earth has been extinguished in the past 40 years.

Ice ages and the consequent sea level changes are another major geological time marker, and the end of the last one 12,000 years ago ushered in the mild, stable climate in which human civilisation has flourished. Today, human-caused global warming is ending that stability, melting ice ever faster. It has already swelled the oceans to levels not seen in 6,000 years. An even greater effect on sea level, though far less well known, is the relentless pumping out of geological water aquifers by humanity, far faster than rainfall can replenish them.

Many of the great transitions cited above actually rank far higher in the geological hierarchy than the humble epoch being considered for the Anthropocene. Top of the ranking is the eon, the most recent of which marks the start of multicellular life on Earth. Next is the era, the most recent of which started after the dinosaurs vanished. Next down the hierarchy is the period, marked most recently by the dawn of humans.

The current epoch began only 12,000 years ago, as civilisation began. But, in the past century or two, humans have developed and deployed the ability to transform the entire planet. Furthermore, and as the global population rises, the pace of change is vastly faster than ever before. If that doesn’t merit official recognition by the keepers of the geological clock, our hopes of ever finding a way to live that keeps the Earth habitable for our descendants will appear more remote than ever. Epoch derives from the Greek epokhē meaning a fixed point of time: declaring the Anthropocene would provide a vital moment for reflection and change.