The hole in the ozone layer is shrinking – thanks to widespread CFC bans

Healing is a phenomenon as coveted as it is rare.

The self-care brigade have long been touting it as an emotional panacea to remedy all the world’s ills. Tech also jumped on the bandwagon, with news that a self-healing smartphone screens are just round the corner.

Trumping all of these is, er, our planet, with a first-of-its-kind study revealing the Earth’s ozone layer may actually be healing itself, albeit with a gentle nudge from globally depleted chlorine levels.

The ozone layer, which protects Earth’s surface from the sun’s harmful radiation, is no stranger to fluctuation, with the size of its hole varying wildly over the years; these annual records from NASA testify to that. Mercifully, a recently published study has confirmed positive news after it showed the hole is indeed healing, with new techniques revealing just why that is.

The study, published in Geophysical Research Letters, is the first to measure directly the amount of chlorine in the atmosphere above Antarctica, a new report from NASA reveals. Chlorine has a history of culpability as the main chlorofluorocarbon (CFC) product responsible for weakening the ozone layer in the first place. The study yielded encouraging results, with the amount of chlorine in the atmosphere above Antarctica down 20% from 2005 to 2016.

There are multiple explanations for the diminished levels of chlorine in the atmosphere, with bans on CFCs doing much of the heavy lifting. Meanwhile, environment-savvy humans can help sustain the positive change by avoiding aerosol products with CFCs in them (check the labels, and opt for spray products over pressurised cans), checking fire extinguishers for “halon” or “halogenated hydrocarbon” active ingredients (if they’re featured, replace the equipment after disposing of it safely) as well as getting rid of pre-1995 fridges, freezers and air-conditioning units.

The data in question was collected by the Microwave Limb Sounder (MLS), a highly technical instrument on the Aura satellite used to detect hydrochloric acid, the product which forms when chlorine atoms react with methane and bond with hydrogen.

The team, led by Susan Strahan, atmospheric scientist at NASA’s Goddard Space Flight Center in Maryland, focused its efforts during the Southern Hemisphere’s winter. “During this period,” explained Strahan, “Antarctic temperatures are always very low, so the rate of ozone destruction depends mostly on how much chlorine there is.” In other words, it’s optimum time to measure ozone loss according to chlorine presence.

Previous attempts at charting the ozone layer’s ebb and flow have centred on the physical size of its hole, so this study marks an exciting deviation from conventional monitoring.

The study’s authors assert that their research shows that ozone depletion decreases in line with the degree of chlorine from CFCs in the atmosphere. Affirmation came from the fact that the 20% reduction is “very close to what our model predicts we should see for this amount of chlorine decline,” explained Strahan.

Image: Andreas Kambanis, used under Creative Commons