The story so far:
Delhi’s plan for cloud seeding is being sold as a bold solution to air pollution. In reality, it is a textbook case of science misapplied and ethics ignored.
Why is Delhi’s air fouler in winter?
Across North India, air quality is poor throughout the year, but it reaches extreme levels in the post-monsoon and winter months. After the monsoon withdraws, dry continental air masses from the northwest dominate the region. The winds weaken and the air becomes stagnant, keeping pollutants from being dispersed efficiently.
Cooler air holds less absolute water vapour and the stable, high-pressure systems that prevail during these months suppress the upward motion needed for clouds to form. The sky may look hazy, but that haze comes from trapped pollution, not from rain-bearing clouds. Rain cannot be conjured out of thin air. It needs water vapour.
For most of the highly polluted cooler months, the atmosphere is too dry and stable to support significant rainfall. Rain does occur occasionally during these months, but these brief spells are typically caused by western disturbances, weather systems that originate in the Mediterranean region and can bring moisture from that region or interact with local systems drawing up moisture from our neighbouring seas. These events can be predicted a few days in advance, but are not a reliable or consistent source of rainfall for North India.
Does cloud seeding help?
Cloud seeding depends on natural clouds; it can’t create them. And even when clouds exist, the evidence that seeding reliably increases rainfall remains weak and contested. And when it rains and reduces pollution, the respite is temporary at best. The overwhelming evidence is that pollution levels go back up within a day or two.
The air pollution problem is not just confined to Delhi. Across North India, air quality is dangerously poor year-round. Yet public debate often treats smog as a seasonal nuisance, normalising pollution and noticing it only when it becomes unbearable. Cloud seeding is just another gimmick in a series of similar unscientific ideas, like smog towers, suggesting that flashy interventions can substitute for serious, structural solutions.
What are the risks of cloud seeding?
The temptation to engineer a shortcut to fix air pollution is understandable — but it raises deeper ethical questions about how science is used, what risks are justified, and who bears responsibility when things go wrong.
Even if the science behind cloud seeding were robust, which it is not, it still involves dispersing compounds such as silver iodide or sodium chloride into clouds to trigger condensation. Silver iodide works for cloud seeding because its crystal structure is very similar to that of ice, so it ‘tricks’ water droplets in the clouds into freezing onto it. These newly formed ice crystals then grow heavy and fall as rain or snow. While generally considered low risk in small doses, repeated use can accumulate in soils and water bodies. The long-term effects on agriculture, ecosystems, and human health remain poorly understood.
Beyond these environmental risks, there is the question of accountability. If cloud seeding coincides with intense rainfall that leads to flooding, causing damage to infrastructure, crops, and livelihoods, or loss of life, who will be responsible? Even if the rainfall and flooding are unrelated to seeding, public perception could still link the two, undermining trust in both science and governance.
What can ‘fix’ the air?
Science has long identified the real cause of North India’s hazardous air: the lack of effective control over emissions from vehicles, industry, construction, power plants, waste burning, and seasonal agricultural fires, compounded by unfavourable meteorology during the cooler months. The solutions are equally clear but remain largely unimplemented: cleaner transport, sustainable energy, better waste management, and urban planning that actually reduces pollution sources.
Yet, instead of reinforcing these priorities, parts of the scientific ecosystem — researchers, advisors, and institutions — are lending credibility to a costly spectacle that will do little to address the sources of the crisis. By attaching their authority to the illusion of quick fixes, they risk wasting scarce public resources, undermining trust, and diverting attention from systemic changes that could make a real difference.
Snake-oil solutions will not clear the air in Delhi or the rest of North India. Instead, courage is required on the ground: to reduce the sources of pollution and pursue equitable, evidence-based action.
Anything less is not just misplaced science — it is an ethical failure, a diversion from the patient, unglamorous work needed to ensure clean air throughout the year.
Shahzad Gani is an Assistant Professor at the Centre for Atmospheric Sciences, IIT Delhi. Krishna AchutaRao is a Professor at the Centre for Atmospheric Sciences, IIT Delhi
Published – October 24, 2025 08:30 am IST
