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Context

Delhi has approved ₹3.21 crore for five experimental cloud seeding trial runs with IIT Kanpur to combat air pollution.

What is Cloud Seeding?

Cloud seeding is a weather modification technique that increases precipitation by introducing substances into clouds to encourage the formation of water droplets or ice crystals.

Mechanism: When suitable clouds are present, seeding agents such as silver iodide (AgI), sodium chloride (common salt), potassium iodide (KI), or dry ice (solid carbon dioxide) are released into them. 

• These agents provide a surface for water vapor to condense or freeze, forming larger droplets or ice crystals that become heavy enough to fall as rain.

Types of Cloud Seeding:

• Static Cloud Seeding: Involves introducing ice nuclei (e.g., silver iodide) into supercooled clouds to facilitate the formation of ice crystals.
• Dynamic Cloud Seeding: Focuses on enhancing vertical air currents within clouds, thereby increasing their capacity for moisture absorption and precipitation.
• Hygroscopic Cloud Seeding: Entails spraying salt particles (e.g., sodium chloride, calcium chloride) into warm clouds to promote droplet coalescence.

How Can Cloud Seeding Potentially Combat Air Pollution?

Wash-out Effect: Artificial rain can "wash out" airborne pollutants, including particulate matter (PM2.5, PM10), sulphur oxides (SOx), and nitrogen oxides (NOx), by bringing them down to the ground.

Scavenging: As raindrops fall, they absorb and physically remove pollutants from the atmosphere, improving air quality.

Moisture Enhancement: Induced rainfall can increase atmospheric moisture and reduce the thickness of smog, making the air appear clearer. 

What are the Major Challenges and Limitations of Cloud Seeding for Air Pollution?

Effectiveness Debate

Effectiveness of cloud seeding for reducing air pollution is scientifically debated, with studies showing mixed and often marginal results.

Dependency on Meteorological Conditions

Cloud seeding requires existing, moisture-laden clouds with sufficient humidity and vertical air motion. 

Delhi's peak pollution in winter often lacks the required conditions, making cloud seeding difficult or ineffective, as acknowledged by experts.

Environmental and Health Concerns:

• Toxicity: Continuous release of silver iodide could accumulate in soil and water, harming aquatic ecosystems, plants, and animals, and disrupting food chains.
• Human Health Risks: Long-term exposure to silver iodide may cause lung irritation, breathing difficulties, skin damage, exacerbate asthma, or, at high levels, lead to argyria or iodism.
• Unintended Weather Effects: Cloud seeding could alter natural precipitation patterns, causing flash floods or droughts in neighboring regions and disrupting ecological balances.

Cost-Effectiveness and Resource Allocation

Cloud seeding operations are expensive (₹55 lakh per trial in Delhi). Critics argue that given the temporary relief (1-2 days) and scientific uncertainties, these funds could be better used for proven long-term solutions to pollution.

Ethical and Legal Quandaries:

• Transboundary Impacts: Cloud seeding in one area might reduce rainfall in neighboring regions, leading to disputes over water rights and liability.
• "Owning" the Clouds: Modifying weather raises questions about who has the right to control natural phenomena and the potential for misuse.
• Lack of Regulation: Existing legal frameworks for weather modification lack provisions for liability, accountability, and environmental impact assessments.

Risk of Diverting Attention from Root Causes

Scientists warn that cloud seeding offers only temporary relief and risks diverting policy attention and resources from fundamental pollution sources like vehicular emissions, industrial discharge, construction dust, and stubble burning.

Way Forward

Prioritize Root Cause Solutions

Implement stringent emission standards for industries and vehicles, promote public transport, adopt sustainable agricultural practices to curb stubble burning, enhance waste management, and enforce dust control measures at construction sites.  

Invest in Scientific Research

More stringent, regulated, and open research is required to understand cloud seeding's effects on air quality across various climates, with an emphasis on its immediate and long-term environmental impacts.

Develop Robust Regulatory Frameworks

Establish clear national guidelines for weather modification technologies, addressing environmental impact assessments, liability, resource sharing, and ethical concerns.

Regional Cooperation

Encourage collaboration among states and with neighboring countries to address transboundary air pollution and potential impacts of weather modification.  

Public Awareness and Engagement

Educate citizens about the sources of pollution and encourage their participation in mitigation efforts.

Integrated Air Quality Management

Adopt a holistic strategy that combines technological interventions, policy reforms, regulatory enforcement, and citizen action to ensure breathable air for all. 

Cloud seeding should be considered only as a last-resort, supplementary measure under specific meteorological conditions, not a standalone solution.

Conclusion

Cloud seeding is an unreliable, temporary, and costly fix for pollution. Sustainable progress demands enforcing regulations, implementing long-term strategies, and controlling emissions, addressing root causes over short-term tech interventions.

Source: NEWSONAIR