Ozone is a molecule composed of three oxygen atoms instead of the more typical two. The Earth’s ozone layer blocks solar ultraviolet radiation that can devastate wildlife ecosystems and cause skin cancer in humans. In the 1960s, the ozone layer was discovered from satellite measurements to be deteriorating at about 8% per decade due to release and chemical reactions with synthetic chemicals known as chlorofluorocarbons, or CFCs. In 1974 Sherwood Rowland and Mario Molina published the first alarm of impending global disaster in the journal Nature. Paul Crutzen added to this inital research and the three atmospheric scientists won the Nobel Prize in chemistry in 1995 for their ozone efforts and scientific whistleblowing.
The most common CFC was brand-name Freon used in air conditioning systems. In 1989 an international agreement called the Montreal Protocol banned further production of these chemicals, and their concentration has slowly decreased in the atmosphere since then. Production levels of CFCs have dropped from more than 1 million tons a year to less than 50,000 tons, with China agreeing to phase out their production of CFCs by 2010. The JGR paper is the first published results directly linking the decline of atmospheric CFC levels to slower ozone destruction.
“A little bit of chlorine destroys a lot of ozone,” Newchurch said in an interview Monday. Chlorinated fluorocarbons last from 45 to 100 years in the atmosphere. Even if the rate of growth in the ozone holes continues slowing, “the CFCs will still be around a for long time after we’re all gone,” the researchers said.