The 1991 Prize was awarded to Professor Paul Crutzen of the Max Planck Institute of Chemistry in Mainz, Germany, one of the world’s leading research scientists in the field of atmospheric chemistry. Professor Crutzen has achieved this eminence by undertaking a series of major research projects over a period of more than 20 years, including studies of ozone layer depletion and the greenhouse effect. He was awarded the Nobel Prize in Chemistry in 1995.