Substances that deplete ozone layer falling in atmosphere
BRISTOL: Since the 1985 discovery of a hole in the ozone layer countries have agreed and amended treaties to aid its recovery. The most notable of these is the Montreal protocol on substances that deplete the ozone layer, which is widely regarded as the most successful environmental agreement ever devised.
Ratified by every UN member state and first adopted in 1987, the Montreal protocol aimed to reduce the release of ozone-depleting substances into the atmosphere. The most well known of these are chlorofluorocarbons (CFCs).
Starting in 1989, the protocol phased out the global production of CFCs by 2010 and prohibited their use in equipment like refrigerators, air-conditioners and insulating foam.
Today, refrigerators and aerosol cans contain gases like propane which, although flammable, does not deplete ozone in Earth’s upper atmosphere when released.
However, ozone-friendly alternatives to CFCs in some products, such as certain foams used to insulate fridges, buildings and A/C units, took longer to find. Another set of gases, hydrochlorofluorocarbons (HCFCs), was used as a temporary replacement.
Unfortunately, HCFCs still destroy ozone. The good news is that levels of HCFCs in the atmosphere are now falling and indeed have been since 2021 according to research I led with colleagues.
This marks a major milestone in the recovery of Earth’s ozone layer – and offers a rare success story in humanity’s efforts to tackle climate-warming gases too.
With this fall in atmospheric levels of HCFCs, we may be turning the final corner in the global effort to repair the ozone layer. There is still a long way to go before it is back to its original state, but there are now good reasons to be optimistic.