Syllabus: Conservation, environmental pollution and degradation, environmental impact assessment
- Definition: Deliberate introduction of substances into clouds acting as condensation or ice nuclei attempting to induce precipitation.
- Historical Background: First experiments conducted in 1946 by American chemist Vincent J. Schaefer; methods include aircraft, rockets, cannons, ground generators.
- Common Substances: Solid carbon dioxide (dry ice) and silver iodide prove most effective seeding materials.
- Supercooled Clouds: In below-freezing temperature clouds, substances form nuclei around which water droplets evaporate creating ice crystals.
- Warm Clouds: Calcium chloride particles provide condensation nuclei for raindrop formation in above-freezing temperature clouds.
Delhi’s Winter Air Quality Crisis
- Year-Round Problem: North India’s air quality poor throughout year, reaching extreme levels post-monsoon and winter.
- Meteorological Factors: Dry continental air masses from northwest dominate; winds weaken causing air stagnation.
- Pollutant Trapping: Cooler air holds less water vapor; stable high-pressure systems suppress cloud formation.
- Haze Source: Sky haze comes from trapped pollution, not rain-bearing clouds; rain requires water vapor.
- Atmospheric Conditions: During polluted cooler months, atmosphere too dry and stable supporting significant rainfall.
- Western Disturbances: Occasional winter rain from Mediterranean-origin weather systems bringing moisture; predictable but unreliable.
Cloud Seeding Limitations
- Dependency: Cloud seeding depends on natural clouds; it cannot create clouds from thin air independently.
- Weak Evidence: Even with clouds present, evidence that seeding reliably increases rainfall remains contested.
- Temporary Relief: When rain reduces pollution, the respite is temporary; pollution levels return within one to two days.
- Regional Problem: Air pollution is not confined to Delhi; entire North India faces dangerously poor quality year-round.
- Public Perception: Debate treats smog as a seasonal nuisance, normalising pollution noticed only when unbearable.
- Gimmick Series: Cloud seeding another unscientific idea like smog towers suggesting flashy interventions substitute structural solutions.
- Environmental and Health Risks
- Chemical Dispersal: Involves dispersing silver iodide or sodium chloride into clouds triggering condensation artificially.
- Silver Iodide Mechanism: Crystal structure similar to ice tricks water droplets into freezing; crystals grow heavy falling as rain/snow.
- Accumulation Risk: Repeated use can accumulate in soils and waterbodies despite being low-risk in small doses.
- Unknown Effects: Long-term impacts on agriculture, ecosystems and human health remain poorly understood scientifically.
- Accountability Concerns
- Flooding Risk: If cloud seeding coincides with intense rainfall causing flooding, responsibility attribution becomes problematic.
- Infrastructure Damage: Potential damage to infrastructure, crops, livelihoods or loss of life raises accountability questions.
- Perception Problem: Even if flooding unrelated to seeding, public perception could link both undermining trust.
- Trust Erosion: Undermines confidence in both scientific community and governance institutions significantly.
Real Solutions
- Emission Sources: Science identifies lack of effective control over vehicles, industry, construction, power plants emissions.
- Waste Burning: Agricultural fires and waste burning compound unfavorable meteorology during cooler months.
- Known Solutions: Cleaner transport, sustainable energy, better waste management, pollution-reducing urban planning remain unimplemented.
- Scientific Complicity: Researchers, advisors, and institutions lending credibility to a costly spectacle addressing no root causes.
- Resource Waste: Attaching authority to quick fixes wastes scarce public resources diverting from systemic changes.
Conclusion
- Addressing Delhi’s air pollution demands courage to reduce emission sources through evidence-based action, not shortcuts. Promoting unproven solutions like cloud seeding represents ethical failure, diverting from sustained systemic work needed for year-round clean air. Quick fixes cannot clear North India’s air; only structural interventions addressing root emission sources provide lasting solutions.
Q- “Cloud seeding is a textbook case of science misapplied and ethics ignored in addressing Delhi’s air pollution crisis.” Critically examine this statement discussing the limitations, risks, and ethical concerns of cloud seeding. (15 Marks)