Friday, June 25, 2021


Paul Crutzen, Nobel laureate who studied ozone and named new 'Anthropocene' era, dies at 87

Paul Crutzen, a Nobel-winning chemist who revealed threats to the ozone layer, developed the concept of "nuclear winter" and concluded that humans were having such a profound impact on the planet that it was time to recognize a new geological epoch - the Anthropocene - died Jan. 28 at a hospital in Mainz, Germany. He was 87.



His death was announced by the Max Planck Institute for Chemistry in Mainz, where Dr. Crutzen directed the atmospheric chemistry department from 1980 until retiring in 2000. A spokeswoman for the institute, Susanne Benner, said he "suffered from several years of illness" but did not specify the cause.

Crutzen was raised in the Nazi-occupied Netherlands and initially worked as an engineer, not a scientist. Though he dreamed of an academic career, he enrolled at a technical school to spare his parents the cost of a university education, and built bridges in Amsterdam before starting a new life for himself in Sweden.

When he spotted a newspaper ad for a computer programming job at Stockholm College, he saw an opportunity. Despite lacking any experience, he applied for the position and got the job - and was soon sitting in on college classes, accumulating enough credits to get a master's degree and apply for a doctorate program in meteorology.

Crutzen went on to spend decades investigating the interplay between humans and the atmosphere, studying the causes of air pollution, the impact of wildfires, the consequences of nuclear war and the depletion of the ozone layer, which earned him a share of the 1995 Nobel Prize in chemistry. 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.


"I was at a conference where someone said something about the Holocene, the long period of relatively stable climate since the end of the last ice age," he told Fred Pearce, author of the climate-change book "With Speed and Violence" (2007). "I suddenly thought that this was wrong. The world has changed too much. So I said: 'No, we are in the Anthropocene.' I just made up the word on the spur of the moment. Everyone was shocked."

He later learned that he was not the first to use the term "Anthropocene," which biologist Eugene Stoermer had employed in the 1980s. Nor was he the first to offer a name for this human-dominated epoch of shrinking forests, rising temperatures and soaring population, which journalist Andrew Revkin once suggested calling the Anthrocene.

But Crutzen's proposal, formalized in a 2002 Nature article titled "Geology of Mankind," quickly took off, spurring an ongoing debate over whether it is time to rewrite geology textbooks and add a new epoch to the planet's timetable, one that emphasizes the powerful role that humans play in shaping the Earth.

"Paul was very good at launching ideas that resonate with a lot of people, and that start to become a central theme of something," said Guy Brasseur, a distinguished scholar at the National Center for Atmospheric Research in Boulder, Colo. In a phone interview, he called Crutzen a master of developing "simple ideas, simple models, that show the essence of a process."

Crutzen was initially known for his work on the ozone layer, the thin atmospheric shield that protects plants and animals from ultraviolet radiation. In 1970, he demonstrated that compounds known as nitrogen oxides - spewed out by microbes in the soil - play a central role in controlling the level of ozone in the stratosphere.

His discovery marked a fundamental breakthrough in understanding the chemistry of the ozone layer, and shook up the debate over manufacturing supersonic transport planes such as the Concorde. Drawing on Crutzen's research, some scientists feared that fleets of supersonic aircraft would pose a threat to the ozone layer by releasing nitrogen oxide into the atmosphere. (The transport planes were never built in large numbers.)

Inspired by his research, chemists Mario Molina and F. Sherwood Rowland published a 1974 article that identified a threat to the ozone layer from chlorofluorocarbons, or CFCs, which were used in everything from air conditioners and refrigerators to hair spray and deodorant. British researchers later discovered a vast "ozone hole" over the South Pole, which Crutzen and other scientists linked to the CFCs.

Their findings paved the way for the Montreal Protocol, a landmark 1987 treaty that phased out the use of ozone-destroying gases. In awarding the Nobel Prize to Crutzen, Rowland and Molina, who died in October, the Royal Swedish Academy of Sciences said that "the three researchers have contributed to our salvation from a global environmental problem that could have catastrophic consequences."


The loss of the ozone was far from the only environmental catastrophe that Crutzen studied. In a 1982 article memorably subtitled "Twilight at Noon," he and chemist John Birks warned of a climate disaster caused by a nuclear war, in which fires rage through cities, forests and oil fields. The resulting smoke would blot out the sun, they concluded, cooling the surface of the planet and jeopardizing agricultural production.

Their theory gained further traction when five others, including astronomer Carl Sagan, co-authored a 1983 Science paper titled "Nuclear Winter." Sagan later discussed the concept on television and campaigned against nuclear weapons, along with researchers such as Crutzen.

"Although I do not count the 'nuclear winter' idea among my greatest scientific achievements . . . I am convinced that, from a political point of view, it is by far the most important," Crutzen said in his Nobel Prize lecture. The theory, he added, "magnifies and highlights the dangers of a nuclear war and convinces me that in the long run mankind can only escape such horrific consequences if nuclear weapons are totally abolished by international agreement."

Paul Jozef Crutzen was born in Amsterdam on Dec. 3, 1933. His mother worked in a hospital kitchen, and his father waited tables but was often unemployed. The family later struggled to find food and fuel during the German occupation, amid a nationwide famine that became known as the "hunger winter."

Several of Crutzen's classmates died before the Swedish Red Cross began dropping packages of food by parachute, and nearly all his classmates lost a year of schooling because they had only a few hours of instruction each week. With special help from a teacher, Crutzen carried on.

In his telling, he excelled in math and physics but, "because of a heavy fever," struggled in his high school final exam. His grades kept him from receiving a university stipend, setting him on a path to join the Amsterdam bridge construction bureau.

In 1958 he married Terttu Soininen, a Finn, and moved to northern Sweden. He joined the meteorology department at Stockholm College (now a university) the next year, and soon learned machine code that he used to program weather prediction models. He received a master's degree in 1963, a PhD in 1968 and a doctor of science degree in 1973.

Crutzen was a postdoctoral fellow at the University of Oxford and worked at the National Center for Atmospheric Research before joining the Max Planck Institute for Chemistry, where he mentored younger researchers such as Birks, his collaborator on the "nuclear winter" paper.

"Paul Crutzen mentored at least hundreds and promoted the careers of thousands of scientists around the world," Birks said in an email. "Besides being a brilliant scientist, he one of the most caring and generous people I have ever known."

Survivors include his wife, two daughters and three grandchildren.

Long after he helped keep pollutants out of the atmosphere through his ozone research, Crutzen made a bold proposal to flood the air with sulfur in an effort to combat global warming. Such "geoengineering" efforts were worth further study, Crutzen argued, especially if humanity did not act quickly to stem emissions and alter consumption habits.

"Imagine our descendants in the year 2200 or 2500. They might liken us to aliens who have treated the Earth as if it were a mere stopover for refueling, or even worse, characterize us as barbarians who would ransack their own home," he wrote in a 2011 essay with journalist Christian Schwägerl. "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."

Published : January 30, 2021

By : The Washington Post, Harrison Smith