Gentle Dutch genius whose work entered the language
Paul Crutzen warned of ‘nuclear winter’ and coined the term ‘Anthropocene’.
The most important Dutchman that you’ve never heard of might just be Paul Crutzen. A Nobel prize-winning meteorologist who died last month, his work - and personality - changed how we understand the relationship of humankind to planet Earth. Not once but three times.
Born in Amsterdam in 1933, the self-described ‘boy from De Pijp’ grew into a world citizen and benefactor of humanity - en groeide uit tot wereldburger en weldoener van de mensheid, reported Amsterdam.nl, the city website. His ideas were visionary, rooted in a career that combined “pioneering research with a flair for conveying scientific ideas,” noted an obituary in the Financial Times.
Crutzen, who has died in Germany, aged 87, was the first scientist to demonstrate theoretically that chlorofluorocarbon gases (CFCs) would cause a hole in the ozone layer. When that hole was subsequently located in Antarctica, the discovery prompted an unprecedented global action to ban aerosol cans, air conditioning and refrigerators.
The term ‘nuclear winter’, which became a household phrase during the Cold War, emerged from an article by Crutzen which considered the possible atmospheric impact of dust and soot from a military strike with nuclear weapons. That was his second persuasive contribution to public and political discourse, although the phrase itself was popularised by others.
A third epoch-defining moment occurred in 2000, during a meeting in Mexico, when an exasperated Crutzen introduced the term ‘Anthropocene’ - reportedly on a whim, in a moment of frustration during an academic debate. The Anthropocene describes our epoch, dating from the late 18th century, when the impact of human activity rivalled nature in altering the process of evolution of planet Earth.
During celebrations in Mainz, Crutzen was driven through the city in an open carriage but refused champagne in protest against French nuclear testing
“He was a kind, gentle genius whose work helped to save the ozone layer; prevent nuclear winter and, by establishing the term ‘Anthropocene’, drive home humanity’s impact on the planet,” Ulrich Pöschl, a director at Germany’s Max Planck Institute where Crutzen ran the department of atmospheric chemistry from 1980 until his retirement in 2000, told the Financial Times.
The son of a waiter and a cook, Crutzen’s childhood was often poverty-stricken. His early education was chaotic, interrupted by the war. Several of his school friends died during the winter famine - hongerwinter, of 1944-45. After military service, Crutzen trained as a civil engineer in order to spare his family the costs of studying at university.
He worked for four years as a bridge-builder for the Amsterdam municipality until 1958, when he moved with his Finnish wife Terttu Soininen to Sweden. Despite having no experience of computer programming, he successfully applied for a job as a programmer in the meteorology department of the institution which became Stockholm university.
In 1995, Crutzen was a co-recipient of the Nobel Prize for chemistry, for his work on the effects of man-made chemicals on the ozone layer. “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,” he said in his Nobel lecture.
The hole in the ozone layer
In Stockholm, Crutzen attended lectures alongside his day job, studying at home during the evenings while working by day as a computer programmer. By 1973, when he obtained his doctorate in theoretical meteorology, he was a pioneer in the field of stratospheric chemistry.
His intention had been to study natural processes, but Crutzen’s early breakthrough was to demonstrate that the atmospheric balance of naturally occurring nitrous oxide and ozone could be altered by exposure to man-made chemicals. The Nobel was shared with Mexican scientist Mario Molina and his US colleague F. Sherwood Rowland, who built on Crutzen’s model for ozone depletion to predict a hole in the ozone layer.
That hole (pictured) was subsequently discovered above Antarctica in 1985 by a team of three scientists from the British Antarctic Survey, prompting an unprecedented agreement between world leaders on the 1987 Montreal Protocol to phase out the use of CFCs in aerosol cans for products such as hairspray and deodorant.
Crutzen believed his ideas had sown the seeds for a thaw in the Cold War
The ban on ozone-depleting chemicals as “a hitherto unique example of how Nobel Prize-winning basic research can directly lead to a global political decision,” said Martin Stratmann, president of the Max Planck Society, in a statement.
Crutzen was the last surviving of the three Nobel laureates, following Molina’s death in 2020. “His work proves that it is possible to do science at the very highest level, while also attending to the moral, political, and cultural ramifications of your work,” Harvard science historian Naomi Oreskes told the Associated Press.
Once in his life, revealed Martijn van Calmthout in Volkskrant, Crutzen purchased a “few cans” of deodorant. Citing an interview from 1985, he said Crutzen made the purchase shortly before collecting his Nobel prize: the scent was intended to carry him (literally, swing along) through the lectures - die luchtjes waren bedoeld om bij lezingen mee te zwaaien.
He didn't own a car, walked to work, travelled reluctantly, preferably by train. During celebrations of his Nobel prize in Mainz, home to Germany’s Max Planck Institute, Crutzen was driven through the city in an open carriage - rondgereden in een open rijtuig. Even then, he refused champagne in protest against French nuclear testing - weigerde hij champagne te schenken uit protest tegen de Franse kernproeven.
In 1982, he co-authored an article with John Ricks, subtitled Twilight at Noon, as part of a series, Nuclear War: The Aftermath, later published as a book. Crutzen and Ricks predicted that soot and dust from a nuclear firestorm could shroud countries in smog, reducing the intensity of sunlight and causing crop failure. From this vivid spectre, other researchers and writers coined the term ‘nuclear winter’ - a possibility that military strategists had ignored for 40 years.
The prospect of a dangerous global winter - een gevaarlijke wereldwijde winter, seized the public and scientific imagination. American astronomer Carl Sagan popularised the concept in the US, despite subsequent and less alarmist studies. As the Pentagon and the Kremlin edged towards detente and nuclear non-proliferation pacts in the 1980s, Crutzen believed his ideas sowed the seeds for the thaw between Superpowers - legde volgens hem de kiem voor de dooi tussen de grootmachten.
The Anthropocene - het Antropoceen - describes an epoch in which humans’ impact on the Earth rivalled that of nature. Crutzen coined the phrase during a moment of frustration at an academic meeting in Mexico, not long after his 66th birthday.
Will Steffen, emeritus professor at the Australian National University who organised the Mexico meeting, recalled that participants discussed the Holocene, the geological epoch that began around 11,700 years ago and - in official scientific terminology - continues to this day. “You could see Paul getting agitated,” Steffen told the FT.
Crutzen interrupted to say: “Stop saying the Holocene! We’re not in the Holocene any more”. Then the Dutch scientist “paused before blurting out that we were in the Anthropocene...It stopped everyone in their tracks”.
Crutzen developed his concept in a January 2000 article, Geology of Mankind, for Nature magazine, and again in an October 2010 piece, ‘Anthropocene man’. In Parool, Jaap Seidell and Jutka Halberstadt described the term as a reference to the undeniable influence of humans on the atmosphere, climate, biodiversity and the soil -- verwijst naar de onmiskenbare invloed van de mens op de atmosfeer, het klimaat, de biodiversiteit en de bodem.
Michael Mann, climate scientist at Penn State university, said the term “elegantly but simply captured the sobering notion that human impacts on our planet can, in just decades, rival the geological forces that led to mass extinctions over the eons.” The Anthropocene is widely understood as either a successor to, or part of, the Holocene era which dates from the last Ice Age, almost 120 centuries ago.
Since the onset of climate change - de aanzet tot klimaatverandering, it was evident to Crutzen that humans had become more powerful than the earth: “Het is evident dat de mens sindsdien sterker is dan de aarde,” he told Volkskrant. Although Anthropocene is not yet recognised as ‘official’ terminology in scientific discourse, Steffen predicts this will happen within three to four years.
Crutzen is quoted as saying this so-called human era began with the invention of the steam engine in 1784 - zou volgens Crutzen het best met de uitvinding van de stoommachine in 1784 kunnen beginnen. A new term was necessary, he argued, because the environmental impact of human activity had escalated over three centuries to a point where the global climate was significantly changed.
To date, 19 Dutch people have been awarded a Nobel Prize. Crutzen’s achievement is perhaps the most urgent to how we live now. His legacy is a unique contribution to the public understanding of climate science, captured in the lexicon of numerous languages. “His name and legacy will live on,” Oreskes told the Associated Press, “but his presence will be sorely missed.”
Paul Jozef Crutzen, chemist (b. December 3, 1933, Amsterdam; d. January 28, 2021, Mainz); Nobel laureate 1995, for demonstrating, in 1970, that man-made chemicals accelerate the destruction of stratospheric ozone which protects the Earth from ultraviolet radiation. m. Terttu Soininen (1958); daughters Ilona (b. 1958), Sylvia (1964).
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