Humans have become a force of nature reshaping the planet on a geological scale—but at a far-faster-than-geological speed. A single engineering project, the Syncrude mine in the Athabasca tar sands, involves moving 30 billion tonnes of earth—twice the amount of sediment that flows down all the rivers in the world in a year. 50,000 large dams have over the past half- century cut the flow by nearly a fifth. That is one reason why the Earth’s deltas, home to hundreds of millions of people, are eroding away faster than they can be replenished. Geologists care about sediments, hammering away at them to uncover what they have to say about the past—especially the huge spans of time as the Earth passes from one geological period to another. In the same spirit they look at the distribution of fossils, at the traces of glaciers and sea-level rises, and at other tokens of the forces that have shaped the planet. Now a number of these scientists are arguing that future geologists observing this moment in the Earth’s progress will conclude that something very odd was going on.
Scientists are increasingly using a new name for this new period. Rather than placing us still in the Holocene, a peculiarly stable era that began only around 10,000 years ago, the geologists say we are already living in the Anthropocene: the age of man. International Commission on Stratigraphy over the boundaries of the Ordovician era do not normally capture headlines. It is one of those moments where a scientific realisation, like Copernicus grasping that the Earth goes round the sun, could fundamentally change people’s view of things far beyond science. It means more than rewriting some textbooks. It means thinking afresh about the relationship between people and their world and acting accordingly.
Thinking afresh is the easier bit. But the wilderness, for good or ill, is increasingly irrelevant. Although farms have changed the world for millennia, the Anthropocene advent of fossil fuels, scientific breeding and, most of all, artificial nitrogen fertiliser has vastly increased agriculture’s power. The relevance of wilderness to our world has shrunk in the face of this onslaught. The sheer amount of biomass now walking around the planet in the form of humans and livestock handily outweighs that of all other large animals. The world’s ecosystems are dominated by an increasingly homogenous and limited suite of cosmopolitan crops, livestock and creatures that get on well in environments dominated by humans. Creatures less useful or adaptable get short shrift: the extinction rate is running far higher than during normal geological periods.