Cruzen, Paul J. (1933 – ) Dutch Meteorologist

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Paul J. Cruzen (1933 – )
Dutch Meteorologist

Paul Crutzen is one of the world's leading researchers in mapping the chemical mechanisms that affect the ozone layer. He has pioneered research on the formation and depletion of the ozone layer and threats placed upon it by industrial society. Crutzen has discovered, for example, that nitrogen oxides accelerate the rate of ozone depletion. He has also found that chemicals released by bacteria in the soil affect the thickness of the ozone layer. For these discoveries he has received the 1995 Nobel Prize in Chemistry, along with Mario Molina and Sherwood Rowland for their separate discoveries related to the ozone and how chlorofluorocarbons (CFCs) deplete the ozone layer. According to Royal Swedish Academy of Science, "by explaining the chemical mechanisms that affect the thickness of the ozone layer, the three researchers have contributed to our salvation from a global environmental problem that could have catastrophic consequences."

Paul Josef Crutzen was born December 3, 1933, to Josef C. Crutzen and Anna Gurek in Amsterdam. Despite growing up in a poor family in Nazi-occupied Holland during 1940–1945, he was nominated to attend high school at a time when not all children were accepted into high school. He liked to play soccer in the warm months and ice skate 50–60 mi (80–97 km) a day in the winter. Because he was unable to afford an education at a university, he attended a two-year college in Amsterdam. After graduating with a civil engineering degree in 1954, he designed bridges and homes.

Crutzen met his wife, Tertu Soininen, while on vacation in Switzerland in 1954. They later moved to Sweden where he got a job as a computer programmer for the Institute of Meteorology and the University of Stockholm. He started to focus on atmospheric chemistry rather than mathematics because he had lost interest in math and did not want to spend long hours in a lab, especially after the birth of his two daughters, Illona and Sylvia. Despite his busy schedule, Crutzen obtained his doctoral degree in Meteorology at Stockholm University at the age of 35.

Crutzen's main research focused on the ozone, a bluish, irritating gas with a strong odor. The ozone is a molecule made up of three oxygen atoms (O₃) and is formed naturally in the atmosphere by a photochemical reaction . The ozone begins approximately 10 mi (16 km) above Earth's surface, reaching between 20–30 miles (32–48 km) in height, and acts as a protective layer that absorbs high-energy ultraviolet radiation given off by the sun.

In 1970 Crutzen found that soil microbes were excreting nitrous oxide gas, which rises to the stratosphere and is converted by sunlight to nitric oxide and nitrogen dioxide. He determined that these two gases were part of what caused the depletion of the ozone. This discovery revolutionized the study of the ozone and encouraged a surge of research on global biogeochemical cycles.

In 1977, while he was the director of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, Crutzen studied the effects of burning trees and brush in the fields of Brazil. Every year farmers cleared the forests by burning everything in sight. The theory at the time was that this burning caused more carbon compounds or trace gases and carbon monoxide to enter the atmosphere. These gases were believed to cause the greenhouse effect , or a warming of the atmosphere. Crutzen collected and examined this smoke in Brazil and discovered that the complete opposite was occurring. He stated in Discover magazine: "Before the industry got started the tropical burning was actually decreasing the amount of carbon dioxide in the atmosphere." The study of smoke in Brazil led Crutzen to further examine what effects larger amounts of different kinds of smoke might have on the environment , such as smoke from a nuclear war.

The journal Ambio commissioned Crutzen and John Birks, his colleague from the University of Colorado, to investigate what effects nuclear war might have on the planet. Crutzen and Birks studied a simulated worldwide nuclear war. They theorized that the black carbon soot from the raging fires would absorb as much as 99% of the sunlight. This lack of sunlight, coined "nuclear inter," would be devastating to all forms of life. For this theory Crutzen was named "Scientist of the Year" by Discover magazine in 1984 and awarded the prestigious Tyler Award four years later.

As a result of the discoveries by Crutzen and other environmental scientists, a very crucial international treaty was established in 1987. The Montreal Protocol was negotiated under the auspices of the United Nations and signed by 70 countries to slowly phase out the production of chlorofluorocarbons and other ozone-damaging chemicals by the year 2000. However, the United States had ended the production of CFCs five years earlier, in 1995. According to the New York Times, "the National Oceanic and Atmospheric Administration reported in 1994, while ozone over the South Pole is still decreasing, the depletion appears to be leveling off." Even though the ban has been established, existing CFCs will continue to reach the ozone, so the depletion will continue for some years. The full recovery of the ozone is not expected for at least 100 years.

From 1977–80, Crutzen was director of the Air Quality Division, National Center for Atmospheric Research (NCAR), located in Boulder, Colorado. While at NCAR, he located he taught classes at Colorado State University in the department of Atmospheric Sciences. Since 1980 he has been a member of the Max Planck Society for the Advancement of Science, and he is the director of the Atmospheric Chemistry division at Max Planck Institute for Chemistry. In addition to Crutzen's position at the institute, he is a part-time professor at Scripps Institution of Oceanography at the University of California. In 1995 he was the recipient of the United Nations Environmental Ozone Award for outstanding contribution to the protection of the ozone layer. Crutzen has co-authored and edited several books, as well as having published several hundred articles in specialized publications.

[Sheila M. Dow ]