Ozone Layer Depletion

Published on 05 Apr 2025

Ozone layer depletion is the gradual thinning of the earth’s ozone layer present in the upper atmosphere. Recent studies show that the 2023 ozone hole has already surpassed the size of the previous three years, covering over 26 million square kilometres, nearly twice the area of Antarctica.

Causes of Ozone Layer Depletion

• Natural factors

• Volcanic eruptions: It release substances, including chlorine and bromine compounds, into the stratosphere which result in ozone depletion.

• Example: The Tongan volcanic eruption of 2022 caused large, rapid depletion of ozone by injecting huge amounts of water vapour into the stratosphere.

• Sun-spots and stratospheric winds: Natural processes like sun-spots and stratospheric winds can cause ozone depletion but the rate of this depletion accounts for only 1-2%.

• Human activities

• Chlorofluorocarbons: CFCs released by solvents, spray aerosols, refrigerators, air-conditioners, etc. are the main cause of ozone depletion.

• Example: Using data from 14 measurement sites around the world, the researchers found that concentrations of CFC-112a, CFC-113, CFC-113a, CFC-114a etc. have increased since 2010.

• Halons: Release of bromine-containing compounds from fire extinguishing systems and explosion suppression systems also deplete ozone.

• Unregulated Rocket Launches: Solid rocket fuel contains a chemical that releases chlorine in the upper atmosphere and destroys ozone.

Effects of Ozone Depletion

• Increased Ultraviolet (UV) Radiation: Ozone depletion allows more harmful UV radiation, particularly UV-B and UV-C, to reach the Earth's surface.

• Example: According to journal Advances in Atmospheric Sciences, decrease in ozone level and the rising magnitude of surface UV radiation from 2011 to 2020 reached 0.5-1.4 per cent per year.

• Health effects

• Skin Cancer: Increased UV levels are linked with an increased risk of skin cancers, including melanoma, squamous cell carcinoma, and basal cell carcinoma

• Cataracts: UV exposure is associated with the development of cataracts, a clouding of the eye's lens that can lead to vision impairment.

• Impact on air quality: Increase in UV radiation can influence chemical reactions in the lower atmosphere, potentially affecting the formation of tropospheric ozone.

• Example: Findings by the Royal Society, the UK's sciences academy, suggest ground-level ozone has increased by about two parts per billion (ppb) each decade since the 1980s.

• Food supplies: UV radiation can damage sensitive crops such as soyabeans and wheat and reduce the yield of crops.

• Example: A 2017 study found that future warming and unmitigated ozone pollution in the US, could cause a decline of 13% in wheat crops, 28% in soybean yield, and 43% in maize by 2050 when compared to 2000.

• Threat to biodiversity: Ground level ozone poses a threat to plants and trees, setting off a cascade of impacts that harms everything from soil microbes to insects, to wildlife.

• Example: A paper published in HAL open science found that ozone also diminished the olfactory abilities of pollinators, reducing their ability to detect pollen sources.

• Phytoplankton Damage: Phytoplankton which dwell in the topmost layer of ocean get exposed to UV light affecting growth, photosynthesis, nitrogen incorporation and enzyme activity.

• Example: It has been estimated that a 16% ozone depletion could result in a 5% loss in phytoplankton, which equals a loss of about 7 million tons of fish per year.

Government initiatives and policy measures

• Ozone cell: It provides necessary services for the effective and on time implementation of Montreal Protocol and its ODS phase-out program in India.

• Ozone Depleting Substances (Regulation and Control) Rule, 2000: This rule regulates the production, trade, import, and export of ODSs as well as the production of products containing ODS.

• Prohibition of use of halons after January 2001: Use of halons is prohibited after 1.1.2001 except for essential use.

International initiatives

• Vienna Convention for the Protection of the Ozone Layer: It serves as a foundation for global efforts to safeguard the ozone layer, but it is devoid of legally obligatory CFC use reduction targets.

• Ozone Research Managers is a forum that was established following the Vienna Convention. It is a forum of experts specialising in ozone modification research.

• A multilateral fund that assists developing countries in transitioning away from ozone-depleting harmful chemicals.

• Every three years, the member countries meet to discuss research and systematic observations in the ozone layer.

• Montreal Protocol: This agreement regulates the production, consumption, and emission of chemical substances that are responsible for ozone depletion.

• It sets a limit on the production of chlorofluorocarbons (CFCs), halons, and other related substances that release chlorine or bromine to the ozone layer of the atmosphere.

• All member parties have specific responsibilities related to the phasing out of various ozone-depleting substances, controlling ODS trade, controlling export and import of ODs, etc.

• Developing and developed countries have equal but differentiated responsibilities.

• Kigali Amendment to Montreal Protocol: It is the 8th amendment which emphasized on the signing countries are expected to decrease the manufacture and usage of hydrofluorocarbons (HFCs) by about 80-85% from their baselines until 2045.

Way Forward

• Implementation of Updated and Enhanced Measures: Evaluate scientific results on a regular basis and, if needed, update and improve policies to deal with new ozone-depleting compounds and emerging concerns.

• Promotion of Ozone-Friendly Technologies: Promote the adoption of ozone-friendly technologies and alternatives across various sectors, including refrigeration, air conditioning, foam manufacturing etc.

• Technology Transfer: Promote the transfer of ozone-friendly technologies to developing countries to ensure their effective participation in global ozone protection initiatives.

• Enhanced Monitoring and Research: Invest in innovative research and monitoring tools to track changes in the ozone layer, study atmospheric processes, and identify any new compounds that deplete the ozone layer.

Tags:
Environment

Keywords:
Ozone Ozone depletion Air pollution Pollution Climate change

Syllabus:
General Studies Paper 3

Topics:
Environment and Climate Change