A tribute to Nobel Laureate and former CSU Adjunct Professor Paul Crutzen

Nobel Laureate Paul Crutzen, recognized in 1995 for his work on the chemistry of ozone depletion.
Nobel Laureate Paul Crutzen. Photo credit: Carsten Costard, MPI-Chemie

Science lost a brilliant researcher and the planet lost a steadfast advocate with the death of Paul Crutzen on Jan. 28. Crutzen, an atmospheric scientist, was one of the first to link human activities to ozone deterioration, leading to the worldwide ban on ozone-depleting substances. He was awarded the 1995 Nobel Prize in Chemistry, with Mario Molina and F. Sherwood Rowland, for discovering the chemical processes that cause ozone depletion.

Crutzen pioneered many other significant scientific discoveries. He was the first to explore biomass burning’s impact on the atmosphere; he warned that nuclear war would lead to nuclear winter; he proved the Earth is in a new epoch influenced by humans, which he termed the Anthropocene; and he started the debate on potential geoengineering to abate the effects of greenhouse gases.

“Any one of these would be a major life’s work for most of us. Yet, they are only a few examples of so many of Paul’s contributions,” said University Distinguished Professor A.R. Ravishankara, a friend of the late professor. “You cannot pick up an important atmospheric chemistry paper without seeing a reference to Crutzen’s work.”

Prior to directing the Max Planck Institute for Chemistry in Mainz, Germany, from 1980 to 2000, Crutzen was an adjunct professor in Colorado State University’s Department of Atmospheric Science, from 1976-81. Around the same time, he served as a senior scientist and director of the Air Quality Division at the National Center for Atmospheric Research in Boulder.

“Paul was a genius who saw things that others missed. His science always started with simple observations that were built to major findings,” Ravishankara said. “For example, seeing a simple pile of clippings burning on South Boulder Road in Boulder led him to examine and espouse the impacts of biomass burning.”

Crutzen was a fountain of ideas, and he shared them freely, Ravishankara said. He encouraged others to pursue his ideas, which resulted in big impacts in the field. He just wanted to know the answers; he didn’t care about receiving credit.

Crutzen mentored many of the current luminaries in atmospheric chemistry. Among those fortunate enough to be mentored by him were CSU Ph.D. graduates Robert Chatfield and Arlin Krueger, and former CSU research associate Jack Fishman. All of them went on to work for NASA.

“I was department head while Paul was a faculty member, and he was a pleasure to work with in all aspects of his appointment,” said University Distinguished Professor Emeritus Tom Vonder Haar. “Paul was a very active adjunct professor because he really enjoyed teaching, advising on research and interacting with students.”

Though he was a world-renowned atmospheric chemist, Crutzen was not formally trained in chemistry. He grew up in Amsterdam during WWII, became a civil engineer and then studied meteorology in Stockholm while working as a computer programmer.

Crutzen is survived by his wife, Terttu, two daughters and three grandchildren. He was 87.

“Paul leaves behind an enormous legacy of science that will be used, remembered and built on for generations,” Ravishankara said. “He also leaves many of us with his legacy of being a great human being, a humble and very generous person, a humorous man quick with a smile, a man who enjoyed life and sports (soccer in particular), and the memory of an ever-present twinkle in his eyes when he saw good science.”