DAILY SCIENCE

The Anthropocene: Paul Crutzen’s Epochal Legacy
He came to science late in his life, helped to preserve the Earth’s protective ozone, and fundamentally changed our views of nature and ourselves
February 14, 2021

If you think about it, it really is an unbelievable chain of events: Earth, a planet shaped by water and home to millions of different life forms, assembles, from a billion molecules, a person who understands its past and its present functions so well that he, with a brain weighing barely one and a half kilograms, develops an epochal idea about its future. And then the earth absorbs this living being back into its ever-circulating stream of matter and energy.

When the news of Paul Crutzen’s death on the 28th of January had not yet the reached world, but only a small circle of fellow scientists, a rising wave of grief and praise began. Humanity had “lost a genius” wrote one person who knew the Nobel Prize winner well, in a joint email group. Another colleague described him as a “scientific giant and a wonderful person.”

Still a third called Crutzen “a great scientist who employed his research to benefit humanity,” adding that he was also “friendly and generous.” Another member of this virtual circle emphasized Crutzen’s concrete contributions: Because of him, the world had become “cleaner, safer, and friendlier.” Of all scientists, he belonged to those “who had done the most to save the planet.” 

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Crutzen’s name will forever remain associated with his greatest idea: the Anthropocene. With his hypothesis that human beings can change the Earth in such profound and lasting ways that they usher in a new chapter, in its history—the geological epoch of human beings—Crutzen pioneered a new view of nature and of ourselves.

Since Crutzen first presented this concept to the bewildered participants of a scientific conference in 2000, his name has become known far outside of academic circles, first in cultural circles, then in political ones. Recently, the UN development agency UNDP devoted its year-end report to the Anthropocene.

Although other individuals had been thinking along the same lines as Crutzen, he united his fame as a Nobel laureate with foresight farsightedness, and conciseness, and thus became “Mr. Anthropocene.”

Even before developing the idea of the Anthropocene, Crutzen had already accomplished enough to deserve a place in school books. He enabled humanity to understand and avoid two of the greatest risks they had inflicted on themselves and the entire planet. Crutzen modeled what would happen in the event of a nuclear war. His “nuclear winter” scenario destroyed illusions of those who wanted to believe that any side could survive such an event.

The second danger that Crutzen identified was small and invisible. With his wealth of knowledge and intuition, he found out that there are substances that attack something on which we are all dependent: the thin protective layer around the Earth composed of ozone molecules. It is only thanks to this ozone layer that life on land was able to develop and that this life has been able to survive, despite the constant irradiation from space.

 

Crutzen’s idea of the Anthropocene broke through the false separation of the human and the natural spheres in a provocative way.

With his calculations, Crutzen paved the way for his colleagues Mario Molina and Sherwood Roland to determine how the ozone layer was being endangered by Chlorofluorocarbons (CFCs), which were used in large quantities in common household items like aerosol sprays and refrigerators. After these findings, Crutzen worked with politicians like the German conservative environment minister Klaus Töpfer to get all the countries to sign the Montreal Protocol, obliging them to decisively reduce and phase out their emissions of “ozone killers.” Since then, the protective ozone layer over our heads has at least partially regenerated – largely thanks to the genius Crutzen. 

Learning that a banal substance—literally the stuff in hairspray and cooling tubes—could destroy the entire Earth greatly worried Crutzen.  “Indeed, nobody had thought that small man-made substances could have a large effect on the stratospheric ozone,” he said in an interview I conducted with him in 2013.

In a time lapse, those events would make a good action-thriller. Humanity races blindly towards an existential danger and then, at the last second, scientists discover the danger, and the antidote. Crutzen never inflated his own role, however. “We were just lucky,” he told me at another occasion.

Triggered by this experience, Crutzen began to draw up long lists of the many other small, yet insidious processes through which we humans are changing the Earth. During sleepless nights, he said, he would often ask himself “What other surprises are waiting for us?” And finally, this list solidified into an overarching idea.

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When he spoke to colleagues in 2000 about the Anthropocene, Crutzen had no idea how successful the concept would be. Initially only taken up by academic circles, this new way of thinking continued to gain ground over the years. Although “Anthropocene” is a rather unwieldy term, it made a great impression on those who weren’t scared off by it. The reason for this is that the idea of a geological epoch shaped by humans breaks through old patterns and barriers of thought.

It is common in Western thought, especially, to separate people and nature. Here civilization; there, the “environment.” Here humans as rational beings; there, biological robots, which is how Descartes defined non-human organisms. Here “history,” with its kings, emperors, and chancellors, and there “geological history,” with its dinosaurs and deciduous trees. This segregation runs through everything: here, the gigantic expanse of commercial areas, cities, farms and industrial sites; there, the much smaller nature reserves.

Crutzen’s idea of the Anthropocene broke through the false separation of the human and the natural spheres in a provocative way: the history of kings, emperors, and chancellors is a continuation of the history of dinosaurs and deciduous trees. And it will be human decisions that determine the future course of geological history.

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From the very start, Crutzen was equally interested in the perils as well as opportunities that come with recognizing we live in the Anthropocene: He hoped that insights into our role will help to change our thinking to such an extent that this new epoch would not become known as the sum of environmental disasters or, even worse, for plunging its namesakes and so much more into the abyss. Does a “good” Anthropocene exist? Crutzen spoke of humans as “guardians of the Earth system” very early on. That said, he never explicitly called himself an optimist; nor did he romanticize this notion of “guardianship.”

 

Crutzen didn’t sugarcoat the situation. When I asked him if he had remained an optimist, he answered: “Did I ever say I was an optimist?”

 

For a while, Crutzen expressed support for geoengineering—i.e. the idea to stabilize the climate through technical means—a stance that garnered him much criticism. Crutzen’s position, however, was much less an expression of technicism than that of naked fear for the consequences of global warming. He wanted to see research develop possible emergency brakes. At one of our last meetings, when his body was clearing showing the signs of his illness, I returned to this point. Geoengineering as a solution? No, he answered. Reducing CO2 emissions is the solution.

Crutzen believed that emission reduction was not simply the exclusive responsibility of engineers. That is why the emergence of “Fridays for Future,” the youth climate movement, gave him such hope.

For the length of his life, Paul Crutzen remained an independent thinker and he reserved the right to also question his own ideas again and again. Once, I picked him up with a taxi to drive together to a conference of artists and scientists. He sized me up for a moment and then said: “The Anthropocene—what is it, actually? What is it?” I suppressed my initial response, which was: Well, if you don’t know, then nobody does. I let the sentence fade away in the Berlin air since it was like Leonardo da Vinci asking, what is painting, actually? 

And in fact, one essential facet of the Anthropocene is that it is not yet clear what exactly it is. An infernal ride into an ecological apocalypse? A crash course to learn that we shouldn’t damage the foundations of our own existence too severely? Or perhaps something more—a new way of thinking, one that combines scientific reasoning with more empathy towards plants, animals, ecosystems? Or even a way to integrate human beings into nature and nature into the human sphere so that in the future “civilization” no longer automatically means colonialist destruction, but rather ecological-social interconnectedness?

Paul Crutzen didn’t sugarcoat the situation. When I asked him if he had remained an optimist, he answered: “Did I ever say I was an optimist?”

As a counterpoint, however, he did believe strongly in positive forces, especially those of art and literature. Despite his despair over what humanity has done to the Earth, he kept a strong core of anthropophilia, as Andrew Revkin has called it. As Crutzen once told me: “Human beings have made so many beautiful things that I often wonder when we are going to make the Earth more beautiful again instead of depleting everything.”

With his insights and ideas, Paul Crutzen inspired millions of people to think about their relationship to nature and the world. According to him, the formal recognition of the Anthropocene by the discipline of geology could easily wait a few years since it wasn’t the official ceremony that was important, but discussion and debate.

The big topics of Crutzen’s life affect every single human being. You don’t have to be an atmospheric chemist or a philosopher to be part of the Anthropocene. It’s enough to go to the supermarket and buy food from all over the world or to drive a car that emits greenhouse gases which will affect the world’s climate for thousands of years.

Every single person is an anthropos. Either unconsciously or deliberately, we are writing a new chapter in the history of the Earth. There can scarcely be a greater legacy than having recognized this. For discovering and defining our role in Earth history, Crutzen deserves a place in our collective memory in league with Alexander von Humboldt and Charles Darwin.

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Translated from German original by Margaret Ries

Photo: ©Todd Bigelow

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