Paul Crutzen

Max Planck Institute for Chemistry / Scripps Institution of Oceanography

Paul Jozef Crutzen was a Dutch atmospheric chemist at the Max Planck Institute for Chemistry and Scripps Institution of Oceanography who received the 1995 Nobel Prize in Chemistry, shared with Mario Molina and F. Sherwood Rowland, for his work on stratospheric ozone depletion chemistry. Crutzen independently and earlier (1970) proposed that nitrogen oxides (NOx) from soil microbes and supersonic aircraft could catalytically destroy stratospheric ozone — catalytic cycle that complements and interacts with the chlorine cycle Molina and Rowland later identified. He also made foundational contributions to tropospheric chemistry, demonstrating the role of methane, carbon monoxide, and hydrocarbons in determining ozone concentrations in the lower atmosphere and the tropospheric hydroxyl radical as the principal oxidizing agent. Crutzen coined the term 'Anthropocene' in 2000 to describe the current geological epoch dominated by human activity, catalyzing a scientific and cultural debate about humanity's impact on Earth systems. He also proposed stratospheric aerosol injection as a potential climate intervention strategy. Crutzen passed away in 2021.