Copernicus Atmosphere Monitoring Service scientists report this
The Antarctic ozone hole will close soon. Similarly to last year’s season, the 2021 hole was one of the largest and longest-lived ever recorded, closing in 95% more time than all the ozone holes monitored since 1979. Copernicus Atmosphere Monitoring Service (Cams) scientists, implemented by the European Center for Medium Range Weather Forecasts (Ecmwf) on behalf of the European Commission with funding from the European Union. “Both Antarctic ozone holes of 2020 and 2021 were quite large and exceptionally long-lasting – explains Vincent-Henri Peuch, director of Copernicus Atmosphere Monitoring Service Ecmwf – These two exceptionally prolonged episodes which occurred consecutively are not an indicator of the fact that the the Montreal Protocol is not working, as, without it, they would have been even more extensive ”. «The interannual variability due to meteorological conditions and dynamic conditions – he adds – can instead have a significant impact on the size of the ozone hole, overlapping the long-term recovery. Cams also monitors the amount of UV radiation reaching the earth’s surface, and in recent weeks we have observed very high UV indices, over 8, in some areas of Antarctica located under the ozone hole. ”
The Montreal Protocol, signed in 1978, is one of the most accredited climate intervention agreements put in place to protect the ozone layer. The protocol bans harmful chemicals linked to the destruction and depletion of the ozone layer, such as chlorofluorocarbons (Cfc) and hydrofluorocarbons (Hfc). These chemicals remain in the atmosphere for extended periods of time and are able to reach the stratosphere, where they contribute to ozone depletion. Thanks to the Montreal Protocol, the concentrations of these chemicals are slowly decreasing. However, due to their extended lifespan, it will still take about four decades for the ozone layer to fully recover. Cams contributes to international efforts to preserve the ozone layer by continuously monitoring and providing high-quality data on its current state. Computerized models of the atmosphere are linked to measurements from satellites and on-site stations aimed at closely monitoring the evolution of the phenomenon. Since the stratosphere’s ozone layer acts as a shield, protecting against potentially harmful ultraviolet radiation, it is critically important to monitor its changes.
«Cams monitors and observes the ozone layer by providing reliable and open access data based on different types of satellite observations and on numerical modeling, which allow to precisely monitor the rise, development and reduction of ozone holes on an annual basis . The data collected, together with our forecasts, allow us to monitor the ozone season and compare its development with that of the last 40 years ”, adds Vincent-Henri Peuch. But how is the ozone hole formed? Substances containing chlorine and bromine accumulate within the polar vortex where they remain chemically inactive in the dark. The temperatures recorded in the vortex can drop below -78 degrees Celsius and the formation of ice crystals in polar stratospheric clouds is possible, which play an important role in chemical reactions. When the sun rises above the pole, solar energy releases chemically active chlorine and bromine atoms into the vortex which rapidly destroy the ozone molecules, causing the hole to form.
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