Welcome to the Anthropocene

Geology moves very slowly, and so do geologists. The Working Group on the Anthropocene was set up in 2009, but only presented its recommendation to the International Geological Congress in Cape Town last Monday. The Working Group’s experts have concluded that we are now living in a new geological epoch: the Anthropocene. That is, the epoch when human beings are reshaping the Earth.

Epochs (e.g. the Triassic, the Jurassic, or the Cretaceous) are usually big chunks of time: tens of millions of years. The Anthropocene, by contrast, is only about sixty-five years old, which is why many geologists are reluctant to accept it as a whole new epoch in the Earth’s history. But they probably will, in the end, because the evidence is already there in the rocks.

The radical idea of defining an entire epoch by the impact of human civilisation on the planet was advanced for the first time in 2000, by Nobel Prize-winning scientist Paul Crutzen. Modern human beings have been around for 200,000 years, he pointed out, but only in 1950 did our numbers and and the products of our science and industry grow so great that we became a dominant factor in the planet’s evolution.

Now we make the weather (by causing global warming with our greenhouse gas emissions). We are even melting the ice and raising the sea level.

We and our domesticated animals account for more than 90 percent of the total weight of all large land-dwelling animals (bigger than a chicken) on Earth. Our crops have pushed wild plants off most of the fertile land on the planet.

And if there are any geologists around a hundred million years from now, they will be able to detect our existence just by examining the rocks.

The acid test for defining a geological epoch is: are there clear differences in the make-up of the rocks? With us, it’s easy. In the 1950s, radioactive elements (radionuclides) from hundreds of open-air nuclear bomb tests appear in the sediments all around the world. 

Even more ubiquitous are the tiny fragments of plastic, the particles of aluminum and concrete, and the tiny balls of unburnt carbon that pour out of our power stations, all embedded in the muds that will one day be rocks. The human race may or may not survive, but we have already left indelible evidence of our existence in the rocks.

The real goal of those who want to declare a new Anthropocene epoch, however, is not just to tidy up the geological record. They want to highlight the fact that, for better or worse, we are now in charge of the entire planet.

Paul Crutzen didn’t just propose a new epoch called the Anthropocene. In 2006, he was also the first scientist to go public and say that we may have to resort to “geo-engineering.” We are disabling the Earth’s natural mechanisms for maintaining a stable environment, he said, and in order to survive we may have to take responsibility for maintaining all the global cycles and balances ourselves.

That is not a good thing. In fact, it is a terrifying thing, because the Earth system is immensely complex and there are large parts of it that we do not even understand yet. It was another scientist, Jim Lovelock, who first pointed out what a huge and ultimately crushing burden we will have to shoulder.

Lovelock’s great insight, as important as Charles Darwin’s theory of evolution in the 19th century, was that the Earth’s living things, its atmosphere, its seas and its rocks are all part of a single interacting system. He boldly called it Gaia, but more timid scientists call it Earth system science. And in the very act of recognising it, he realised that it was breaking down.

Writing in 1979, he warned that if we disable Gaia’s natural functions, then one day we will wake up to find that we have inherited “the permanent lifelong job of planetary maintenance engineer. Gaia would have retreated into the muds, and the ceaseless intricate task of keeping all the global cycles in balance would be ours.

“Then at last we would be riding that strange contraption, ‘the spaceship Earth’, and whatever tamed and domesticated biosphere remained would indeed be our ‘life support system’. 

“We can guess that at less than (ten billion people) we should still be in a Gaian world. But somewhere beyond this figure...lies the final choice of permanent enslavement on the prison hulk of the spaceship Earth, or gigadeath to enable the survivors to restore a Gaian world.”

So far we are only seven and a half billion people, but that’s no consolation. The world’s per capita energy consumption is so much higher than Lovelock foresaw in 1979 that we may be on the brink of that final desperate “choice” already. (And UN figures predict that we will be at ten billion by 2050 in any case).

Welcome to the Anthropocene.