Weather check: Paul Crutzen

Paul Crutzen, Nobel laureate and one of the world’s most distinguished climate scientists, died on 28 January 2021, at a hospital in Mainz, Germany, following several years of illness. He was 87.

Crutzen shared the 1995 Nobel Prize in Chemistry with Mario Molina and F. Sherwood Rowland, “for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone”, says the Nobel Prize organisation.

His death was announced by Martin Stratmann, president of the Max Planck Society, where Crutzen worked as director of the Atmospheric Chemistry Department, in Mainz, from 1980 to 2000.

“Paul Crutzen was a pioneer in many ways,” Stratmann says. “He was the first to show how human activities damage the ozone layer. This knowledge about the causes of ozone depletion was the basis for the worldwide ban on ozone-depleting substances – a hitherto unique example of how Nobel prize-winning basic research can directly lead to a global political decision.”

Among Crutzen’s many citations as a researcher was advancement of the theory of “nuclear winter”, in a series of articles and books written with chemist John W Birks, beginning in 1982 with “The Atmosphere After a Nuclear War: Twilight at Noon”, in the journal Ambio, in which they describe the catastrophic effects of nuclear explosions igniting fires that send vast amounts of fossil fuel smoke into the atmosphere, choking out life on the planet.

In its obituary for Crutzen, the Washington Post says that for all his accomplishments, “he was perhaps best known in recent years for popularizing ‘the Anthropocene’, a poetic new term that he first used in 2000”.

Crutzen expanded on his concept of the Anthropocene in a 2002 article in the journal Nature.

“For the past three centuries, the effects of humans on the global environment have escalated,” he wrote. “Because of these anthropogenic emissions of carbon dioxide, global climate may depart significantly from natural behaviour for many millennia to come. It seems appropriate to assign the term ‘Anthropocene’ to the present, in many ways human-dominated, geological epoch, supplementing the Holocene – the warm period of the past 10–12 millennia.”

Crutzen was born in Amsterdam on 3 December 1933. In his autobiography published by the Nobel Prize organisation, he describes how in 1940 the German army overran the Netherlands; interruption to his education was among the many hardships he endured.

At the end of World War II he was able to resume studies and did well at mathematics and physics, although “chemistry definitely was not one of my favourite subjects”. He also became proficient in French, English and German.

With his parents struggling to make ends meet, Crutzen gave up on his dreams of going to university and instead went to a trade school to train as a civil engineer, which led to work for a bridge-building company. While on holiday in Switzerland he met Terttu Soininen, a student at the University of Helsinki. They married and settled in Sweden, where Crutzen resumed his job as an engineer.

“All this time I had longed for an academic career,” he says.

His opportunity came in 1958 when he saw an advertisement in a Swedish newspaper from the Stockholm University Department of Meteorology, looking for a computer programmer. 

“Although I had not the slightest experience in this subject, I applied for the job and had the great luck to be chosen from among many candidates,” he says. 

Crutzen says at that time the Meteorology Institute of Stockholm University and the associated International Meteorological Institute “were at the forefront of meteorological research and many top researchers worked in Stockholm for extended periods”.

He explains that one “great advantage” of being in a university department was that he was able to sit in on lecture courses. By 1963 he had earned a Master of Science degree, combining mathematics, mathematical statistics, and meteorology. He completed his PhD in meteorology with distinction in 1968. 

The California-based Scripps Institute of Oceanography, where Crutzen served as a research associate from 1979 to 1984, says he “published over 360 peer-reviewed scientific journal articles, another 135 scientific publications in research journals, and 15 books. 

“He was one of the most highly cited scientists in the world, was bestowed numerous awards and honours, and was a member of many scientific academies.”

In 2011, Crutzen and Berlin-based journalist Christian Schwagerl published “Living in the Anthropocene: Toward a New Global Ethos”, in Yale Environment 360, an online magazine published by Yale University’s School of the Environment.

“Imagine our descendants in the year 2200 or 2500,” they write. “They might liken us to aliens who have treated the Earth as if it were a mere stopover for refuelling, or even worse, characterise us as barbarians who would ransack their own home. Living up to the Anthropocene means building a culture that grows with Earth’s biological wealth instead of depleting it. Remember, in this new era, nature is us.”

Crutzen is survived by his wife Terttu, his daughters Ilona and Sylvia, and three grandchildren.