Whose Campaign Saved the Ozone Layer?

In 1974, chemists Mario Molina and F. Sherwood Rowland at UC Irvine published a paper showing that chlorofluorocarbons (CFCs, used in refrigerators, air conditioners, and aerosol sprays) were being broken down by UV radiation in the stratosphere, releasing chlorine atoms that catalytically destroyed ozone molecules. A single chlorine atom could destroy 100,000 ozone molecules. Their warning was initially met with fierce industry opposition. The discovery of the Antarctic ozone hole by Joe Farman British Antarctic Survey team in 1985 confirmed the crisis. This led to the Montreal Protocol (signed 16 September 1987), which phased out CFCs and related substances. It has been ratified by every UN member state — the only UN treaty to achieve universal ratification. Molina, Rowland, and Paul Crutzen received the 1995 Nobel Prize in Chemistry. The ozone layer is recovering and is expected to return to 1980 levels by approximately 2066.