In India, to fight against pollution, the government is considering “artificial rain” – Libération

In India, to fight against pollution, the government is considering “artificial rain” – Libération

The Indian executive has announced that it is banking on cloud seeding to dissipate air pollution. The process, while uncertain, turns out to be temporary and rather costly.

Every autumn, India suffocates. Since the beginning of November, its capital New Delhi has been buried under a toxic pollution fog. To remedy this, the Indian government wants, among other things, to make it rain. Without resorting to any form of incantation, the local authorities wish seed clouds. This scientific technique involves spraying sodium iodide or salt into clouds to trigger condensation in the form of rain. The Indian capital is considering spraying a salt mixture and has therefore asked the Kanpur Institute of Technology (IIT) to prepare to take action from the air by plane or by ground, using of cannons.

In India, pollution peaks, resulting from a mix of emissions from factories, vehicles and fires caused by farmers in surrounding regions, intensify with the arrival of winter: colder air traps pollution. According to the University of Chicago, a resident of New Delhi – regularly ranked the most polluted capital in the world – loses an average of twelve years of life due to air pollution. The megalopolis sometimes has levels of PM2,5 (fine particles affecting cardiovascular and respiratory health) more than thirty times higher than the ceilings decreed by the World Health Organization.

“It should rain a lot”

Closure of schools, construction site shutdowns, alternating traffic: since the beginning of November, the surface measures taken by the capital to try to dissipate pollution have continued. Cloud seeding is the latest. But the effectiveness of this technique remains unresolved. Currently, science does not yet have exact certainty as to its power of action and success. “Just because there is sowing doesn’t mean it’s going to rain. And even less rain enough,” explains Olivier Boucher, climatologist at the Pierre-Simon-Laplace Institute.

If the rain were to spread, the amount of water would probably not be enough. “It would have to rain a lot for the microparticles to be cleaned. If India managed to drop one or two millimeters of water, the change in air quality would barely be measurable. says Olivier Boucher. But for his part, one of the project leaders, Sachchida Nand Tripathi, professor of sustainable energy engineering at IIT Kanpur, insisted: “Even very modest rainfall is effective in reducing pollution.”

110 euros for 000 square kilometers

While the COP28 in Dubai, and the UN Secretary General pleads for a real “exit” from fossil fuels, this “band-aid” measure rules out any resolution of the underlying issues. Hoping for rain to fall for a few days, India does not blame lifestyles or over-industrialization processes at the origin of pollution. Once the rains stop, the polluted air masses will return. Ann Harrison, advisor on climate issues for the NGO Amnesty International explains that this “technology would risk maintaining dependence on fossil fuels and not enabling the complete, rapid and equitable elimination [of pollution, editor’s note] which we urgently need to protect human rights”. Marine De Guglielmo Weber, scientific director of the Defense and Climate Observatory and teacher-researcher at the Institute of International and Strategic Relations, adds: “While cloud seeding can, at best, slightly attenuate pollution peaks, it is by no means an effective strategy to respond to such a health emergency and the associated excess mortality.”

The cost of such a technique seems just as high as the doubts surrounding it. The local government of Delhi has decided to take charge "the totality" of financing these artificial rains, reported the Indian daily The Hindustan Times. But if the exact price has not been made public, specifies AFP, other Indian media mention the sum of 10 million rupees (approximately 120 dollars or 000 euros) for an area of ​​110 square kilometers.

India is not the first country to spend large sums to combat air pollution. China, in particular, also regularly budgets billions of dollars to try to change its weather conditions. Since 1958, this Asian giant has aimed to strengthen the water supply in its cities and countryside and plans, by 2025, to strengthen its capacities. This is what worried India, before it too used this process. The Economic Times reported in October 2019 that India was complaining about the "militarization [Chinese] the weather" because of the risks of modification of rainfall regimes on its territory and the possible impacts on the flow of its watercourses.

Risk of conflict

A real influence on water resources, cloud seeding raises essential geopolitical questions. By using this process, a State could “being accused by your neighbors of “stealing” their rainfall, or on the contrary, of causing floods on their territory”, explains Marine De Guglielmo Weber. The risk between these two countries would be to see a conflict arise around the sharing and management of water resources, “because they would accuse each other of producing environmental insecurity, by causing droughts or floods”, continues the researcher.

Seeding remains an unregulated process and can encourage competition for clouds to secure precipitation. Only the Enmod convention prohibited in times of war “to use environmental modification techniques for military or any other hostile purposes”. But this international treaty is not binding, does not apply in peacetime and – although signed by India – has not been ratified by the entire international community.

While the first sowings were planned for November 20 or 21 in India, members of the government postponed the action sine die. The weather conditions were obviously not favorable and it was necessary to have a “Western disruption” stronger in order to maximize the chances of success. Cloud seeding in New Delhi will wait a little longer.

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