Antarctic Ozone Hole is a seasonal and severe thinning of Stratospheric ozone over Antarctica, mostly from August to November during the Southern Hemisphere spring.
- In 2025, it peaked at just over 21 million sq km, well below the 2006 record (29 million sq km).
- Stratospheric ozone (good Ozone) is found at 10-40 KM above Earth's surface, and protects Earth from UV radiation from the Sun.
Causes of Ozone Hole/ozone layer depletion in Antarctica:
- Ozone depleting Substance (ODS) Release: Emissions of Chloro Floro carbons (CFCs), halons, hydro chlorofluorocarbons (HCFCs), and methyl bromide reach the stratosphere.
- UV radiation breaks these substances, releasing chlorine and bromine atoms that rapidly destroy ozone.
- Meteorological Drivers: Polar vortex traps air and concentrates chemicals, while extreme cold forms Polar Stratospheric Clouds that accelerate ozone-destroying reactions.
- Return of sunlight: In spring (September and October) sunlight returns to the region, providing the energy for the catalytic ozone-destroying reactions to occur.
Impacts of ozone layer depletion:
- Health Risks: Higher incidence of skin cancer, cataracts, and weakened immunity due to increase in harmful UV-B radiation reaching the surface.
- Ecosystem Damage: Reduced plant productivity and disruption of marine food chains.
Major Treaties and Mechanisms for protection of ozone layer
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