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Antarctic Ozone Hole Closes Early in 2025
Antarctic Ozone Hole Closes Early in 2025
Context: The Antarctic ozone hole, which forms annually between August and November, closed unusually early on December 1, 2025, according to Copernicus (EU Earth Observation Agency). This year’s hole was the smallest in five years and showed higher ozone concentrations, signalling accelerating recovery under the global ban on ozone-depleting substances.
What is the Antarctic Ozone?
- The ozone layer is a protective shield in the stratosphere (10–50 km above Earth) that absorbs most of the Sun’s harmful ultraviolet (UV-B) radiation.
- The Antarctic ozone hole refers to the seasonal thinning of the ozone layer over Antarctica, first discovered in 1985.
- It appears during the austral spring (September–November) when unique atmospheric conditions trigger chemical reactions that destroy ozone molecules.
What were the major causes behind it?
- Chlorofluorocarbons (CFCs): Widely used in refrigerants, aerosols, and solvents; they release chlorine atoms that destroy ozone molecules.
- Halons and other ozone-depleting substances (ODS): Used in fire extinguishers and industrial processes.
- Chemical reactions on polar stratospheric clouds (PSCs): Extremely cold Antarctic winters form PSCs, which provide surfaces for chlorine and bromine reactions that accelerate ozone destruction.
- UV radiation: Breaks down CFCs and halons, releasing chlorine and bromine that catalyse the destruction of ozone.
Why was it formed in the Southern Hemisphere?
- Extreme Cold Temperatures: Antarctic winters create polar stratospheric clouds (PSCs).
- Unique Chemistry: PSCs provide surfaces for chemical reactions that convert chlorine into ozone-destroying forms.
- Springtime Sunlight: When sunlight returns in September, these reactions accelerate, causing rapid ozone depletion.
- Geography: The polar vortex (a strong wind system) isolates Antarctic air, trapping ozone-depleting chemicals and intensifying the effect.
- This combination of cold, isolated air and returning sunlight makes the Antarctic ozone hole more severe than in the Arctic.
What measures were made to deter and mitigate further expansion of this hole?
- Montreal Protocol (1987): A landmark international treaty that bans the production and use of CFCs and other ODS.
- Global Phase-Out: Countries phased out CFCs in refrigeration, aerosols, and industrial processes.
- Hydrofluorocarbons (HFCs): Introduced as substitutes (though later regulated due to their greenhouse effect).
- Kigali Amendment (2016): Strengthened the Montreal Protocol by targeting HFCs.
- Monitoring & Research: Agencies like Copernicus, NASA, and WMO track ozone recovery annually.
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The Source’s Authority and Ownership of the Article is Claimed By THE STUDY IAS BY MANIKANT SINGH
