were a major hazard that threatened human life on Earth, and risked damaging the conditions needed for any terrestrial life.
No matter how aggressively the chemical industry opposed demands made by environmentalists and scientists like Crutzen, Molina and Rowland to ban CFCs, the case was won in 1987. The United Nations drew up the Montreal Protocol, the single most effective international environmental treaty to date, which called for a gradual phase-out of harmful CFCs, used primarily as coolants. In 1997, the Kyoto Protocol was ratified, which aimed to drastically cut carbon dioxide emissions and nitrous oxide (N2O) emissions.
Since then, a slow but constant regeneration of the ozone layer over Antarctica has taken place. In 2012 and 2013, scientists at NASA and the Alfred Wegener Institute in Germany reported that the Antarctic ozone “hole” had become noticeably smaller, for the first time.8 There is now a chance that the Antarctic ozone “hole” will disappear by 2050–—so long as climate change and the extreme durability of CFC molecules do not thwart this.9
Currently, researchers are optimistic that the ozone layer is regenerating globally and will be permanently restored. What would have happened if Paul Crutzen had not survived the “hunger winter” in Amsterdam and no one had undertaken research like his?
What if he and his colleagues had not had the academic freedom and sufficient funding to explore the chemistry of the ozone layer without any specific aim?
What if Thomas Midgley had put much more aggressive and faster-acting bromine instead of fluorine into refrigerators and aerosol sprays, right from the beginning, well before reliable instruments for measuring the chemistry of the atmosphere existed?
What if explorers like Farman hadn’t spent long nights and bitterly cold days in the Antarctic to make measurements that, at the time, did not interest anyone?
Questions like these concern Paul Crutzen, who says that he has often asked himself since then: “What other surprises may await us?”
The repair of the ozone layer in the twentieth century was dependent on many coincidences. Models show that the ozone layer could have completely disappeared by 2050 had CFC emissions persisted. When Crutzen received the Nobel Prize for Chemistry in 1995, together with Molina and Rowland—or perhaps we should say the “Nobel Prize for Salvaging the Ozone Layer”—he conveyed how utterly humiliating it would have been for humanity to have destroyed the atmospheric layer that protects life on Earth, by the expedience of using aerosol sprays and refrigerators, unaware of the damage being caused. “I can only conclude that mankind has been extremely lucky.”
So, in the twentieth century, individuals were indeed making human history but also global history. On the one hand there was Thomas Midgley, the inventor of a substance that was endangering the hundred-million-year-old life-protecting atmospheric layer, and on the other, there were Crutzen, Johnston, Molina, Roland and others who, having recognized what was happening, demanded action. Events high up in the sky, were being determined not just by the interaction of molecules, temperature and pressure, but also by the work of chemists synthesizing new substances, and by the scientists who were investigating the effects of these substances. Human work manifest in the form of notes, index cards, laboratory diaries and scientific papers led the way to a new global reality.
For the first time in Earth’s history, the results of human activity could be read, as if written high up in the sky.
Paul Crutzen was possessed by his discoveries about the ozone layer. So, back at his desk at the Max Planck Institute, he set about making a list of the ways in which humans were transforming the planet. His list was long—and it grew longer. The more aware Crutzen became of everything that humanity was doing to the Earth, the more a new idea began to form in his mind. He realized that the prevailing view that mankind is miniscule whereas nature is limitless, and that humans only scratch the surface of Earth’s processes, is fundamentally wrong. In his Nobel Prize acceptance speech, he said: “The experiences of the early 1970s had made it utterly clear to me that human activities had grown so much that they could compete and interfere with natural processes.”
This far-reaching notion grew in Crutzen’s scientific mind until it burst onto the scene in early 2000. In February of that year our then sixty-seven-year-old scientist went to Cuernavaca, Mexico, to take part in an International Geosphere-Biosphere (IGBP) conference, a forum for Earth system research, hosted by the United Nations. The debate revolved around human impacts on the environment and, time and again, the term for the geological epoch in which we live came up: the Holocene. The Holocene is said to have started 11,700 years ago, as the last Ice Age came to an end. Crutzen remembers the moment thus: “The chairman mentioned the Holocene again and again as our current geological epoch. After hearing that term many times, I lost my temper, interrupted the speaker and remarked that we are no longer in the Holocene. I said that we were already in the Anthropocene. My remark had a major impact on the audience. First there was silence, then people started to discuss this.”
The Australian climate researcher Will Steffen describes the scene like this: “Scientists from IGBP’s paleo-environment project were reporting on their latest research, often referring to the Holocene, the most recent geological epoch of Earth history, to set the context for their work. Paul, a Vice-Chair of IGBP, was becoming visibly agitated at this usage, and after the term Holocene was mentioned again, he interrupted them. “Stop using the word Holocene. We’re not in the Holocene any more. We’re in the … the … the … (searching for the right word) … the Anthropocene!10
The word landed among the experts like a time-bomb. Anthropos: the Greek word for “humans,” cene: from kainos, the Greek word for “new,” Anthropocene: the new epoch of humans.
In the coffee break after the session, this new word was virtually the only topic of conversation. Crutzen had just redefined the context in which humanity exists on Earth. With it, he had portrayed everything humans do to and with Earth, normally measured in days, years and centuries, in a whole new way. Crutzen suggested a geological scale, of thousands and even millions of years. He had asserted that human activity has affected the Earth, on a geological scale.
The scientists in that conference room in Mexico were profoundly shaken because the Nobel Prize Laureate for Chemistry—one of the most often cited natural scientists in the world—was not only describing the past with this new term (something to which geologists are accustomed) but he was also redefining and connecting to the future of a world that is only just emerging: a new Earth sculpted by humans.
From the perspective of the Anthropocene, the ozone layer story will be just one of a hundred or a thousand ways in which humans are fundamentally altering this planet, 4.6 billion years after its formation. Until Crutzen’s statement in Mexico, we had seen all this mainly from a narrowly short-term human perspective, and for the most part, we were unconscious of the consequences our actions had for the globe.
1. Source: extensive interview with Paul J. Crutzen, 2013 and: http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1995/crutzen-lecture.pdf.
2. John R. McNeill, Something New under the Sun: An Environmental History of the Twentieth-Century World. New York: Norton, 2001.
