Photo by Janwikifoto, courtesy Wikimedia Commons
While studying chlorofluorocarbons (CFCs), which were widely used in consumer products during the late 20th century, chemist Mario Molina discovered in the 1970s that the chemical was accumulating in the atmosphere and destroying the ozone layer. He became a spokesperson for limiting the usage and production of CFCs, but the full significance of his discovery was not recognized until much later. He won the Nobel Prize for Chemistry in 1995. He has taught at MIT as well as the University of California in San Diego and Irvine.