“Stop using the word Holocene! We’re not in the Holocene any more. We’re in the Anthropocene!” Twenty years ago, Dutch atmospheric chemist Paul Crutzen made this then startling claim at a scientific conference in Cuernavaca, Mexico. Since then, the concept of a new geological era has not only been accepted, but is now widely used to describe the age in which we live – an age characterized by the profound changes that human beings are causing to the Earth system. By the time Paul Crutzen died in January this year, his arguments, once seen as controversial, had become broadly established within the international scientific community. The only point on which scientists still disagree is the exact point in time when the Anthropocene era can be said to have begun.

Geoscientists like Reinhold Leinfelder, a professor in geobiology at Freie Universität Berlin and a specialist in Anthropocene research, believe that it started in the mid-1950s, a period when socio-economic growth had accelerated to unprecedented levels. As a result, “technofossils,” such as elemental aluminum, concrete and brick fragments, and plastic, began to accumulate as sediment in the earth in huge quantities. Archaeologists and historians are more likely to argue that the Anthropocene started as soon as Homo sapiens began to settle and use tools.

“Geologically speaking, that would be the pre-Anthropocene,” says Reinhold Leinfelder. “The real question is, how can humanity become part of the Earth’s system in a way that the planet can tolerate?” Leinfelder is a member of the Anthropocene Working Group (AWG), an international research group that brings together scientists and academics from a variety of disciplines, including geosciences, ecology, history, philosophy, and even international law. The AWG is currently putting together data on how humans have changed the Earth since the last ice age around 12,000 years ago, data that can then be used to help identify potential solutions.

“Technical Species” Will Soon Outnumber Natural Organisms

Before modern humans showed up, the planet’s biosphere was a product of evolution. “In the time we’ve been on Earth, the technological progress that has emerged from our cultural development has led to us humans adding a vast technosphere to the biosphere,” says Reinhold Leinfelder. This in itself was a kind of evolution, if we consider how the invention of the wheel has now given us self-driving cars, or how we’ve replaced the bush telegraph with the smartphone. “If we add up all the 'technical species' that we’ve created,” says Leinfelder, “we might find that the sum total is higher than the species number of fossilized and living organisms that have ever existed on earth.”

It Takes 12,000 Kilograms of Rock to Produce Just Four Grams of Gold

For the planet to tolerate and sustain our technological tendencies, we need daring and sustainable new concepts. Reinhold Leinfelder argues for a circular economy based on the model of the biosphere. “All ecosystems are dependent on one single, renewable primary energy source – the sun,” Leinfelder explains. “Sunlight provides the energy plants need to grow. Plants are eaten by animals, and these animals are in turn eaten by larger animals.”

When living organisms die, their biomass is broken down by decomposers – bacteria, fungi, and a huge variety of microscopic organisms that disperse their components throughout the soil, thus making their nutrients available for reabsorption by plants. “But sadly, we have failed to put similar processes in place for the objects that make up the technosphere,” notes Leinfelder. In fact, the precise opposite is true. To take an extreme example, 12,000 kilograms of rock have to be mined and broken down to extract just four grams of gold. Only around one-fifth of the total stone contains any ore at all. The gold is extracted through a process that uses a huge amount of water along with toxic cynanides and mercury.

“We’re left with huge rubbish dumps and a dramatic increase in pollution, and all for the sake of a tiny fraction of end product,” says Leinfelder. Scientists in Israel have calculated that humans are currently using around one billion (1,000,000,000,000!) tons of material taken from the lithosphere. This material includes sand and stone for construction, along with metal for machines, transportation, and all sorts of useful technologies from cutlery to laptops. “If we factor in all the additional materials that have to be blasted out of the earth first in order to get to the material that is actually wanted, it’s seven times as much,” adds Leinfelder. “We have calculated that if we add up everything that human beings have ever moved around and transformed into something else, it comes to around 30 billion tons. And this total sum is what we call the technosphere.” In comparison to humans’ impact on the Earth, the impact of natural erosion is negligible.

Think about Recycling Before You Start to Build

Humanity has become a geological factor, yet our actions are far removed from the kind of circular economy that the Earth could support. To align with the biosphere, humans would need to begin with primary energy, using only renewable sources rather than fossil fuels. This is already beginning to happen. “But recycling – or in biological terms, decomposing – is still in its infancy,” says Leinfelder. “Of course, we can melt down gold again and re-use rare earths from smartphones. The problem isn’t so much practical as economic. People won’t choose to recycle as long as we can get new products from the natural world more cheaply. But we could build in decomposition, in the sense of taking things apart to recycle them, right from the initial stages of manufacturing and construction.”

One example, notes Leinfelder, is “urban mining,” in which the components from demolished houses are ground down and the concrete re-used for new buildings. Grinding down the old materials still costs energy, but it’s far better, argues Leinfelder, than simply dumping rubble on landfill sites, where it remains unavailable to the economic cycle. The scientist points out that we could also start building in a different way entirely, using only sustainable materials. For example, we could stop using sand for construction, which is becoming more and more difficult to source in the form it is needed.

We do have one resource, however, that is pretty much inexhaustible – human intelligence. Nowadays scientists from all sorts of disciplines are thinking about the Anthropocene, analyzing it from their particular perspective and developing new technologies and concepts. But besides this kind of “drilling down” into individual scientific questions, which is necessary in any discipline, we also need integrative thinking, says Leinfelder. For example, new, flagship positions at universities could be created for researchers specializing in the area.

“The Earth is one integrated system. Everything is connected, and everything interacts. We can see this in the soil, for example, which is affected by all sorts of human processes and can very quickly reach a tipping point. But that’s essentially true for the entire planet,” Leinfelder explains. “This is why we need a new research culture, and, I suspect, a new kind of teaching in universities.”

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This text originally appeared in German on April 24, 2021, in the Tagesspiegel newspaper supplement published by Freie Universität.