Crutzen, Paul Josef (1933-2021), a Dutch chemist, discovered that certain compounds of nitrogen and oxygen break down ozone. Ozone, a form of oxygen in Earth’s upper atmosphere, shields Earth from much of the sun’s ultraviolet radiation. The ozone-destroying compounds are produced in automobile exhausts and in various industrial processes. Crutzen’s work contributed to the realization in the 1970’s that Earth’s protective ozone layer is threatened by human activity, and the resulting environmental legislation that included laws concerning vehicle emissions. Crutzen shared the 1995 Nobel Prize for chemistry with the American chemists Mario Molina and Frank Sherwood Rowland, who had studied the effects on the ozone layer of different substances, the chlorofluorocarbons (CFC’s). See Molina, Mario Jose ; Rowland, Frank Sherwood .
Crutzen was born in Amsterdam, the Netherlands, on Dec. 3, 1933. He trained as a civil engineer. He worked in bridge construction in Amsterdam, did military service, and then worked in house construction in Sweden. He then took a job as a computer programmer at the department of meteorology at Stockholm University, Sweden. This enabled him to attend some university courses and eventually take higher degrees, gaining the equivalent of a doctorate in meteorology in 1968, and one in philosophy in 1973.
The work he did for his advanced degrees involved programming a computer with a model (set of mathematical equations) describing atmospheric processes. He became especially interested in the chemistry of the ozone layer. He believed that the amount and distribution of ozone could not be accounted for by known processes, and suggested that nitrogen compounds might play an important role.
Crutzen spent the period between 1969 and 1971 working at the Clarendon Laboratory at Oxford University in the United Kingdom. Analyzing data from American scientists, he confirmed his idea that compounds of nitrogen and oxygen originating from bacterial processes rise to the upper atmosphere and chemically break down ozone.
Crutzen’s work paved the way for later research concerned with the ozone layer. Fears were raised about the destructive effects of nitrogen compounds released by supersonic passenger planes, and by space shuttles. The public concern raised by this was a powerful stimulus to research into the effects of human activity on the atmosphere. When Rowland and Molina studied the effect of CFC’s on the ozone layer, they compared the amounts being produced with the quantities of nitrogen compounds that were regulating the ozone layer and became alarmed—a realization made possible by Crutzen’s work.
Crutzen continued at the University of Stockholm until 1974. In later years, he was director of research at the National Center for Atmospheric Research, an independent agency of the United States government in Boulder, Colorado, and thereafter worked in Germany at the Max Planck Institute for Chemistry in Mainz. Crutzen died on Jan. 28, 2021.
