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Ozone Hole Over the Antarctic Region

Why is it in the news?

  • A recent study has revealed that the ozone hole over the Antarctic region has not only expanded in size but has also become thinner.

Ozone Layer

  • The ozone layer is a protective layer in Earth’s stratosphere, situated between 15 to 35 kilometres above the Earth’s surface.
  • It comprises ozone molecules (O3), formed primarily through photodissociation, where high-energy solar photons break oxygen molecule (O2) bonds, releasing single oxygen atoms that combine to form ozone.
  • The ozone layer serves as a shield against harmful ultraviolet (UV) radiation from the sun.
  • Its absorption of UV radiation is critical to protecting human health and preventing damage to ecosystems, including skin cancers, eye damage, and harm to marine life and vegetation.

The Emergence of the Ozone Hole

  • The ozone hole refers to the thinning or depletion of the ozone layer, particularly over Antarctica.
  • It was first observed in the 1980s and was primarily caused by the widespread use of chlorofluorocarbons (CFCs) and other ozone-depleting substances.
  • Ozone depletion occurs when chlorine and bromine atoms, released from compounds like CFCs, interact with ozone molecules, leading to the destruction of ozone.
  • A single chlorine atom can destroy over 100,000 ozone molecules, depleting ozone faster than it naturally forms.


Factors Contributing to the Ozone Hole

  • Climate and dynamics of the Southern Hemisphere, such as temperature and wind patterns.
  • Aerosols from events like wildfires and volcanic eruptions.
  • Changes in the solar cycle.
  • The presence of the polar vortex over Antarctica.


International Agreements for Ozone Protection


AgreementYear AdoptedKey Purpose
Vienna Convention1985The Vienna Convention, the first international agreement of its kind, aimed to foster cooperation among nations and facilitate the sharing of information regarding the impacts of human activities on the ozone layer.
Montreal Protocol1987The Montreal Protocol is a significant multilateral environmental agreement. Its primary purpose is to regulate the production and consumption of nearly 100 ozone-depleting substances (ODS) to protect the ozone layer from further depletion.
Kigali Amendment2016The Kigali Amendment is an extension of the Montreal Protocol. It commits numerous countries to reduce the use of Hydrofluorocarbons (HFCs), which are a new generation of ozone-depleting substances, in order to address their environmental impact.


UV Radiation and its Classification

UV TypeWavelength RangePenetration PowerInteraction with Ozone Layer
UV-ALong-wavelengthHighReaches Earth’s surface
UV-BShorter wavelengthIntermediateAbsorbed by ozone layer, reaches epidermis
UV-CHighest energyLowBlocked by ozone layer

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