Among the many alarming crises of the 1980s -- Iran-Contra, the satanic panic, feathered hair -- the hole in the ozone layer was perhaps the most dire. Scientists warned that industrial chemicals were basically punching a hole in the sky, letting in lethal radiation from the sun that would threaten all life on Earth.
Yeah, whatever happened with all that? Trace Dominguez has some history and updates in today's DNews report.
Ozone is an allotrope of oxygen -- three oxygen atoms linked together -- that occurs naturally in the atmosphere. The ozone layer isn't an actual layer, as such. The term refers to scattered ozone molecules floating in the stratosphere, anywhere from 6 to 30 miles overhead.
Ozone performs a vital function, for life as we know it, by absorbing harmful UVB radiation coming off the sun. Without the ozone layer, we would all cook in a slow-motion apocalypse of squamous cell carcinoma. So scientists were understandably concerned when atmospheric measurements showed that the ozone layer was gradually disappearing.
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The culprit turned out to be chlorofluorocarbon, a chemical used for refrigeration all over the world. Patented by DuPont as freon, it was sold in everything from air conditioners to refrigerators to aerosol hair sprays. At peak production, companies were putting out a million metric tons of CFCs every year.
When in the upper atmosphere, CFCs are subject to a chemical process called photodissociation. Ultraviolet radiation breaks a chlorine atom off the CFC, which in turn bonds with the nearest oxygen atom to chlorine monoxide. CFCs were literally ripping the ozone layer apart, molecule by molecule.
In 1987, the international treaty known as the Montreal Protocol initiated the process of phasing out industrial CFC production worldwide. The treaty was a huge victory for scientists and environmentalists as chemical companies fought fiercely to keep profitable CFCs legal. But that a whole 'nother story.
The good news? The CFC ban appears to be working. Things were touch-and-go for a while but a study published in Science earlier this year found the hole had decreased in size from the year 2000 -- and most of that decrease was specifically because of the Montreal Protocol.
Best case scenario: According the new study, the ozone layer may be back to 1980 levels by 2040. Whew.
-- Glenn McDonald
NASA Earth Observatory: Ozone
Science Mag: Ozone layer on the mend, thanks to chemical ban
NASA: Ozone Hole Watch