The late 20th century was marked by the recognition that humans could significantly affect the environment, even Earth itself. But, beyond localized ecological concerns over DDT and the vaguer terror of nuclear winter, by the early 1970s we hadn't much considered the potentially global consequences of industry and chemistry. This was especially true in the case of the chemically inert chains of chlorine and fluorine atoms strapped to a carbon backbone known as chlorofluorocarbons, or CFCs.
In 1974, scientists F. Sherwood Rowland and Mario José Molina argued CFCs were not as harmless as they seemed. Instead of washing out of the sky through rainfall or oxidation, they floated into the upper stratosphere, where solar ultraviolet radiation broke them apart and set off an ozone-destroying chemical reaction. In 1985, the British Antarctica survey detected a hole in the ozone layer over Antarctica, and the rest is history [sources: Nobel Prize; Nobel Prize].
As a child in Mexico City, Molina admired his aunt, a chemist, and emulated her by converting a spare bathroom into a makeshift chemistry lab. He studied in Mexico and abroad, and made his groundbreaking discovery concerning CFCs during his postdoctoral stint with Rowland at University of California, Irvine. The work earned him the 1995 Nobel Prize in chemistry, an honor he shared with Rowland and Paul J. Crutzen, a pioneer in studying nitrogen oxide effects on ozone destruction. Today, Molina studies strategic approaches to energy and the environment [sources: Crutzen; Nobel Prize; Nobel Prize].