The Ozone Hole

Station 10

In the 1980s it was discovered that the protective ozone layer over the North and South poles was becoming progressively thinner, thus allowing more and more harmful UV radia-tion to reach the Earth’s surface. This saw the emergence of the term ‘ozone hole’. Chemists Mario J. Molina and Frank Sherwood Rowland had already warned of the negative impact of chlorofluorocarbons released by humans on the ozone layer. Paul J. Crutzen explained the influence of polar stratospheric clouds in the formation of the ozone hole. Three scientists were awarded the Nobel Prize for Chemistry for this work in 1995.

Chlorofluorocarbons (CFCs) used in spray cans and refrigerants are the main contributors to the ozone hole. They accumulate in the stratosphere and cannot be broken down due to temperature and airflow conditions. The light from the sun produces radicals that damage the ozone molecules.

As well as numerous scientific awards, the discovery by Molina, Rowland and Crutzen had political consequences. 1987 saw the signing of the Montreal Protocol for the protection of the ozone layer. The global environmental agreement contributed significantly to the replacement of ozone-depleting CFCs with other substances and to the slow recovery of the ozone layer.

Der dritte Nobelpreis

Paul J. Crutzen wurde 1980 als Nachfolger von Christian Junge Direktor der Abteilung Chemie der Atmosphäre am MPI für Chemie. Er startete seine wissenschaftliche Karriere mit 25 Jahren als Programmierer im Meteorologischen Institut der Universität Stockholm. Messkampagnen des Instituts brachten ihn in Kontakt mit ersten meteorologischen Modellen. Als Assistenzwissenschaftler arbeitete er sich mehr und mehr in die Fotochemie des atmosphärischen Ozons ein.

In den 1980er Jahren untersuchte Paul Crutzen, welchen Einfluss Eispartikel in Polaren Stratosphärenwolken auf den Ozonabbau haben. Seine Erklärung: An der Oberfläche der Partikel werden Chlor und Brom zu hochreaktiven katalytisch wirksamen Formen und zerstören anschließend die Ozonmoleküle.

1995 erhielt Paul Crutzen zusammen mit seinen Kollegen Mario Molina und Sherwood Rowland den Nobelpreis für Chemie.

2012 schrieb Paul Crutzen zu seiner Entdeckung:
„We were all flabbergasted and it took time to explain it scientifically. At the same time it clearly had a life-threatening dimension for humankind on earth. It was clear that something had to be done, and in the 1980s the CFC gases were banned from production. Nevertheless it will take several years to heal the ozone hole. The question now is: are we able to counter the effects of the other greenhouse gases released by human activities?”

Go to Editor View