Artificial rain as panacea for pollution crisis not a long-term solution, too expensive, say experts

NEW DELHI: Can artificial rain dissipate toxins in the air? As the skies over several parts of north India turn blue again and pollution levels improve from ‘severe’ but continue to be ‘very poor’, the question of whether cloud seeding can really be a long-term solution gathers urgency.

It is a tempting prospect and nothing more, say scientists, stressing on the need to tackle the problem at its root. Artificial rain is not just expensive - an estimated Rs 1 crore to induce rain in an approximate 100 square kilometre area - but also offers temporary respite.

“The respite artificial rain offers is short-lived... the return of polluted air swiftly restores hazardous levels, highlighting the need for more sustainable solutions,” Sunil Dahiya, an analyst with the Centre for Research on Energy and Clean Air said.

The long-discussed issue came under the spotlight again when the Indian Institute of Technology-Kanpur announced its success with cloud seeding tests to combat persistent air pollution in the Delhi-NCR region, generating a mix of excitement and scepticism.

Sachchida Nand Tripathi, a distinguished expert in sustainable energy engineering at IIT Kanpur, explained that the technique involves injecting salts into clouds to induce rain formation.

“IIT Kanpur has in its possession an aircraft equipped with a cloud seeding device. The aircraft can fly up to 10,000 feet for about four hours. The institute has also developed its novel seeding solution of salts which has been tried for cloud seeding to initiate artificial rains,” Tripathi, the winner of the Infosys Prize 2023, for his research on large-scale sensor-based air quality network, said.

“Data from India and other countries show an enhancement of about 20 per cent in rainfall in seeded clouds compared to non-seeded ones,” he said.

The sustainable impact of this process is under scrutiny, Tripathi added.

While the precise cost of cloud seeding experiments in India remains undisclosed, an estimated Rs 1 crore is believed to be required to induce rain in approximately a 100 sq km area. The tentative estimate came from an IIT Kanpur team headed by Manindra Agrawal, professor at the Computer Science and engineering department at the institute.

For several weeks in November and early December, the air quality index (AQI), which measures the concentration of PM 2.5 or fine particulate matter in the air, consistently surpassed the 400 mark in Delhi-NCR. This was nearly ten times the acceptable limit.

According to environmental researcher Krishna AchutaRao, cloud seeding relies on specific atmospheric conditions to be effective.

AchutaRao noted that cloud seeding has been in practice for many decades.

“The first attempt to prove its efficacy in India was published recently by scientists from the Ministry of Earth Sciences and they found an increase of about 18 per cent due to seeding - that too in the month of July,” he added.

While cloud seeding has found applications in air quality management and dust suppression in several countries, these endeavours have been sporadic at best. China has invested significant sums to modify weather patterns, aiming to protect agricultural regions and enhance air quality, particularly in anticipation of large-scale events. Similar efforts have been observed in other countries, such as Indonesia and Malaysia.