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The stratosphere ozone layer is slowly recovering and the recovery will be complete in most parts of the atmosphere in the coming decades, according to the latest bulletin by the World Meteorological Organization (WMO).
The bulletin with the updated status of the ozone layer by WMO-Global Atmosphere Watch bulletin returned after a gap of seven years. Until 2016, it was brought out by WMO in collaboration with the European Ozone Research Coordinating Unit.
The annual bulletin will provide the latest information on stratospheric ozone and ultraviolet radiation around the world.
The ozone layer protects life on Earth from harmful solar ultraviolet (UV) radiation. Depletion of the ozone layer, which was first observed in the 1980s, allows free passage of UV rays into the inhabited layers of the atmosphere, causing skin cancer, cataracts and damages the immune system. The rays also harm other ecosystems by altering biochemical processes and growth of species.
Thus, monitoring and protecting the ozone layer is imperative for the health of humans and the environment. To this end, the Montreal Protocol of 1987 banned the production and consumption of ozone-depleting substances.
As of today, 99 per cent of their production and use has been phased out, according to WMO. And a steady recovery of the ozone layer has been observed as a result.
“In 2022, higher than normal ozone columns were observed in the tropics and subtropics and lower than normal ozone columns at higher latitudes, particularly in the southern hemisphere,” WMO noted in a press statement.
The new ozone and UV bulletin replaces the earlier WMO Antarctic and Arctic ozone bulletins that had a narrower technical focus, according to the United Nations climate monitoring and research body.
The bulletin emphasises the importance of continued high-quality measurements of stratospheric ozone and its drivers to ensure that the long-term changes in the ozone layer are well measured and their causes understood, it added.
"The success of the Montreal Protocol can inspire the world to address many other global environmental challenges through collective action, supported by science," said Petteri Taalas, Secretary-General of WMO.
Unfortunately, climate change is slowing down the recovery of the ozone layer, he added. “Ozone depletion is also affecting the climate of the lower atmosphere.”
The latest bulletin offered some observations on the status of the ozone layer and factors that impacted it in 2022.
Strong signs were recorded that indicate the ozone layer over the Antarctic region is recovering, it noted. In 2022, the Antarctic ozone hole had a relatively late onset in September and a relatively large extent and depth in October and November, according to the bulletin. “The delay and decreasing early September Ozone Mass Deficits are considered key pieces of evidence that the ozone layer is beginning to recover.”
In January 2022, Hunga Tonga-Hunga Ha'apai volcanic eruption — the largest in a 100 years — increased the water vapour content of the stratosphere by 5-10 per cent, the scientists wrote in the latest update.
The additional water vapour has resulted in less ozone in the lower stratosphere of the southern hemisphere in 2022, they added. “Enhanced water vapour and aerosol in the polar vortices are expected for the next several winters, which could result in more polar stratospheric clouds, enhanced ozone depletion, and larger and longer-lasting ‘ozone holes’.”
The bulletin also incorporated some more policy and assessment activities undertaken last year to work towards a full recovery of the ozone layer. These included the SunSmart Global UV app, The general trust fund for financing activities on research and systematic observations relevant to the Vienna Convention for the Protection of the Ozone Layer, monitoring networks operating Brewer and Dobson spectrophotometers, among other things.