Joachim von Braun | PAS President

Commemoration of Prof. Paul Crutzen

Paul Crutzen died in January 2021 at the age of 87 years. He was Director of the Atmospheric Chemistry Department at the Max Planck Institute for Chemistry in Mainz, Germany, from 1980 to 2000.

Together with our Academician colleague Mario Molina and with F. Sherwood Rowland, he received the 1995 Nobel Prize for Chemistry for identifying how nitrogen oxides erode the earth’s ozone layer, and for discovering the chemical processes that cause the ozone hole.

He became a Pontifical Academy of Science member in 1996.

He was the first to show how human activities damage the ozone layer. This knowledge about the causes of ozone depletion was the basis for the worldwide ban on ozone-depleting substances, a unique example of how basic science can directly lead to a global political decision serving people and planet.

Paul Crutzen’s scientific work focused on the impact of humans on the atmosphere, climate and earth system. In addition to his research on atmospheric chemistry and the ozone hole, he also examined the potential consequences of a global nuclear war.

In the early 1980s, together with John Birks, he discovered that a darkening of the earth’s atmosphere from the fires ignited by nuclear war would lead to a nuclear winter, resulting in a dramatic decline of the earth’s habitability.

His findings were essential contributions to the global efforts and achieve achievements in nuclear disarmament. This was science for peace.

Paul Crutzen coined the term “Anthropocene”, which he used to describe the current era in which human activity is shaping our planet through the profound influences in global atmospheric, biological and geological processes.

He commented on the scientific and social debates that followed his proposal on the concept of the Anthropocene. Together with his friend Professor Ramanathan, he warned early on the drastic measures that are needed at the international level to reduce the concentrations of greenhouse gases, in particular CO2, through energy savings, renewable energy sources and sequestration of CO2.

Paul Cruzten discussed the extent to which mankind exploits the natural resources of planet earth in numerous publications and public lectures. He typically ended presentations with a picture of himself and his grandson, calling on the audience to preserve the earth for future generations.

We pray for him and always remember our great colleague.