Recent increases in an unregulated ozone-depleting substance, could delay recovery of Antarctic ozone levels by 5–30 years, depending on emissions scenarios.
The findings, published in Nature Communications, suggest that a previously ignored chemical called dichloromethane may now be contributing to ozone depletion and should be considered to improve future ozone predictions.
Long-lived chlorine species, such as chlorofluorocarbons (CFCs), led to depletion of the stratospheric ozone layer in the 1980s, most drastically seen in the Antarctic.
After introduction of the UN Montreal protocol in 1987, which regulated emissions of ozone-depleting substances, stratospheric ozone began to recover and is projected to return to pre-1980 levels in the second-half of this century.
The Antarctic ‘ozone hole’ is expected to fully recover sometime between 2046 and 2057.
However, atmospheric concentrations of dichloromethane — a short-lived, ozone-depleting substance not regulated by the Montreal Protocol — have risen in recent years and could be contributing to ozone loss.
Study lead author Dr Ryan Hossaini, from the Lancaster Environment Centre at Lancaster University, said: “Dichloromethane is a man-made ozone-depleting chemical that has a range of industrial applications. Unlike CFCs and similar long-lived gases that are responsible for most ozone depletion, dichloromethane has a short atmospheric lifetime so has not been controlled by the Montreal Protocol. Despite this, increased production has led to a rapid increase in its atmospheric concentration over the past decade.”
“While ozone depletion from dichloromethane is currently quite modest, it is uncertain how the amount of this gas in the atmosphere will change in the future. Our results show that continued sustained growth in its concentration could substantially delay recovery of the ozone layer, offsetting some of the future benefits of the Montreal Protocol.”
Continue reading at Lancaster University.
Image via NASA
