In July, Mexico's Ministry of Agriculture launched a new phase of the national cloud-seeding program in the country's northern and northeastern states. Since 2020 and amid a severe drought in the state of Baja California, the rain-making technique, involving planes flying into clouds to release silver iodide, has been regularly used to extinguish fires, fill dams and save livestock and crops. Seeding campaigns are financed both by the National Commission for Arid Zones (Conaza), a branch of the Ministry of Agriculture, and by local governments.

Each of these rain-inducing operations was carried out by Mexican company Renaissance, with a technology that is "pioneering and unique in the world," according to its founder and CEO, Alejandro Trueba Carranza. "We use silver iodide, as other companies do, but our method is different: We apply it in liquid form and below the clouds, which allows us to direct them where we want," said the agricultural engineer. "On the other hand, the liquid form can be used in summer and in the desert, whereas application by rockets, as is done in the rest of the world, cannot work with high temperatures."

The first of the Renaissance trials took place in 1977 in Iowa in the United States and in the state of Puebla in Mexico. From 2013 onward, the company developed its "Rainmate" product, which, in addition to silver iodide, contains chemical additives and acetone, although its precise composition is not known. Seven years later, Renaissance carried out its first mission in Baja California, covering a million hectares. Since then, the Mexican company has carried out 277 flights, up to June 2023, in 10 Mexican states. It claims to have increased rainfall in these areas by around 70%.

Faced with the repeated use of this technique, the scientific community has been asked to assess both the benefits and the possible environmental consequences. But, in Mexico as elsewhere, there is a lack of solid scientific studies to make a definitive statement.

Sergio Raul Canino Herrera, a researcher at the Faculty of Marine Sciences at the Autonomous University of Baja California, analyzed 15 rainwater samples in 2021 after cloud seeding in different localities. "The concentration of silver iodide was very low (on the order of 0.01 ppm). None of the samples had a concentration level that could be measured with the equipment we have," said the professor. "On the one hand, we're hoping for more powerful equipment to repeat the analyses, and, on the other, we'd also have to look for the other chemical components used in their product."

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