source: The Quint
Introduction
The Ozone layer, present in the Earth’s stratosphere, is of course well known for its ‘Superman’ properties- Protecting the Earth from harmful Ultraviolet radiation and acting as an invisible shield!
Ozone
Ozone is a molecule consisting of three Oxygen molecules, formed through the action of Ultraviolet light and electrical discharge on dioxygen (O2). It is a more unstable molecule than O2 and Ozone is constantly formed and destroyed in the stratosphere, with the total amount remaining relatively stable.
Ozone Depletion
Ozone decomposes in contact with halogens such as Chlorine and Bromine. ‘One Chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere.’[1]
Therefore compounds that release halogens when exposed to intense UV light are what contribute to Ozone depletion, where the destruction of ozone molecules is sped up by man made chemicals so that the equilibrium between creation of molecules and destruction is compromised.
Ozone depleting substances, ODS, that release chlorine and bromine are Chlorofluorocarbons, hydrofluorocarbons, carbon tetrachloride, methyl chloroform, halons and methyl bromides.
Ozone Holes
Scientists realised in the 1970s, that the ozone layer was being threatened by accumulation of gases in the stratosphere and in the 1980s, a hole in the layer above Antarctica was discovered.
To combat this The Montreal Protocol on Substances that Deplete the Ozone Layer agreement was signed by 197 UN member countries in 1987 to phase out Ozone depleting substances.
2020
The global lockdown due to the pandemic in 2020 was a period of recovery for nature where rivers and ponds became cleaner, the air quality improved, due to reduced emissions from vehicles and industries. During the lockdown in 2021, the 2020 Antarctic ozone hole closed. Though some scientists attribute this to the ending of a ‘strong, stable and polar vortex’, there does seem to be a link with the reduced emissions during the lockdown.
Conclusion
From the lockdown, it was evident that the sate of the environment is not past hope and with collective and consolidated efforts, one can definitely reverse the damage we have done. The Ozone layer is expect to recover to the 1980 levels, before the appearance of the holes by 2040 for most of the world and by 2066 for the entire planet. However, ironically, geoengineering experiments to reduce global warming can damage the ozone layer. The intentional injection of aerosols in the stratosphere to increase reflection of sunlight and lower the amount of heat entering the troposphere, “could also affect stratospheric temperatures, circulation and ozone production and destruction rates and transport”.
All of us protect ourselves by preserving the ozone layer through simple everyday actions, instead of looking for easy fixes. So, next time you are tempted to put on the AC, check if your terrace is breezy and instead sit outside. If the roads and the weather allows, walk to the market instead of taking the car. When you leave the room, remember to switch off light and power points.
Little actions add up - all for the better!
Written by Treya Mukherjee ( BSc Physics Hons)
References:
https://www.downtoearth.org.in/news/environment/ozone-layer-to-recover-in-4-decades-but-aerosol-injection-may-undo-gains-unep-87010
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