Title: Main Causes of Ozone Layer Depletion
Content: English Explanation of Indian Game Answer
The ozone layer, a critical shield protecting Earth from harmful ultraviolet (UV) radiation, has faced significant depletion, particularly over Antarctica. Here are the key causes of ozone layer holes:
1. Chlorofluorocarbons (CFCs) and Ozone-Depleting Substances (ODS)
Primary Culprits: Human-made chemicals like CFCs (e.g., Freon), halons, and other industrial compounds.
Mechanism: CFCs are stable in the lower atmosphere but rise to the stratosphere. There, UV radiation breaks them down, releasing chlorine and bromine atoms. These atoms act as catalysts, destroying ozone molecules (O₃) through链式反应.
Impact: A single CFC molecule can destroy up to 100,000 ozone molecules.
2. Polar Stratospheric Clouds (PSCs)
Seasonal Amplification: In winter, polar regions become extremely cold, forming PSCs. These clouds provide surfaces for chemical reactions that convert stable chlorine reservoirs (e.g., ClCN₂) into reactive chlorine gas (Cl₂).
Springtime Depletion: Sunlight in spring triggers massive ozone destruction, creating the iconic "hole."
3. Ozone-Depleting substances (ODS) from Human Activities
Historical Use: CFCs were widely used in refrigeration, aerosols, andCFCs were banned under the Montreal Protocol (1987). However, their long atmospheric lifetime (decades) means effects persist.
Other ODS: Halons (fire extinguishers), carbon tetrachloride (solvents), and methyl chloroform.
4. Vulnerability of Antarctica
Unique Conditions: The ozone hole over Antarctica forms annually due to prolonged polar darkness and cold temperatures, which accelerate chemical reactions.
5. Global Response and Recovery
Montreal Protocol: A landmark treaty phased out ODS. Since 1987, global CFC production has dropped by over 99%.
Progress: The ozone layer is expected to recover to pre-1980 levels by 2060–2070, though challenges like illegal CFC emissions persist.
Key Takeaway:
The ozone hole crisis highlights the interconnectedness of human activities and environmental systems. While progress is evident, vigilance remains critical to prevent reversals.
Answer for Indian Game (MCQ/True/False):
Correct Answer: The primary cause is the release of CFCs and other ozone-depleting substances.
Explanation: CFCs catalyze ozone destruction in the stratosphere, exacerbated by polar meteorological conditions.
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