Cloud Seeding: A Controversial Technique that Mexico Implements to Cause Rain

Mexico has been involved in cloud seeding since the 1950s, and the government has carried out cloud seeding programs in various parts of the country to increase precipitation and combat drought. In March, the National Commission for Arid Zones (Conaza), a dependency of the Ministry of Agriculture, announced that it would launch a new rain stimulus program in Tamaulipas and Baja, California. However, it is a practice that was also implemented in 2021 in Coahuila, Zacatecas, and Durango, and that has been increasing over the last decade.

Cloud seeding in Mexico is mainly used in agricultural and forest areas. However, it is a controversial technique against which various scientists have opposed. One of the most famous is the one conducted near Mexico City to increase rainfall in the El Bosque dam.

How does Cloud Seeding Work?

Cloud seeding is a method of modifying precipitation in an area by artificially inducing rain or snowfall from cloud stimulation. The technique consists of adding certain substances, such as silver iodide, potassium iodide, or dry ice, in the clouds to favor the formation of precipitations.

When the seeding agent (substance bombarded into the cloud) is introduced into the clouds, it acts as a nucleating agent, promoting the formation of ice crystals or water droplets. As these particles get larger and heavier, they fall to the ground as rain. Factors such as cloud temperature or wind can vary the effects.

Cloud seeding is often used in areas experiencing drought or low rainfall, but also for agricultural purposes, to put out fires, or to control ash from a volcano. It is also used to favor airport conditions and disperse fog. Although the effectiveness of cloud seeding and its long-term effects are debated, its use is widespread in places like the United States, China, Australia, and Russia.

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Why is Cloud Seeding a Controversial Method?

Although cloud seeding is a method that is not only implemented in Mexico, it has its contradictions. The countries implementing it argue it is a safe technique to stop drought and stimulate rain. However, there are several risks associated with this practice. Some of the possible bets are:

• Impact on the environment: Cloud seeding can affect a region's ecological balance and air quality, depending on the technique used and the substance or chemical "seeded" in the cloud. The dangers also lie in the fact that the impact of these chemicals on the soil, water, ecosystems, etc., has not been studied in depth.

• Health effects: Some substances used in cloud seeding, such as silver iodide, can be toxic to humans and animals. This depends on the concentrations and amounts. However, many questions exist about that regulation and how those amounts are measured.

• Economic cost: Cloud seeding can be expensive, and some critics argue that the money invested in the technique could be used more effectively in other water conservation and management programs.

These variations, which until now are unpredictable, raise doubts in the scientific community. "I can modify [a cloud]. What I don't know is if I'm going to increase the rainfall or even suppress it because that can also happen," says Fernando García, a cloud physicist at the National Autonomous University of Mexico (UNAM) for the Nature Magazine.

According to Nature Magazine, in Mexico, this service is provided by the company Renaissance, which uses RainMate technology. According to an investigation carried out by the same scientific journal: "In 2022, a scientific advisory committee of the National Civil Protection System (Sinaproc) of Mexico advised against Conaza implementing cloud seeding projects without completing tasks such as a cost-benefit analysis, a verification of the success of the technology in increasing rainfall and studies to assess the environmental impact of silver iodide". For this reason, although there are weighty sources that maintain that it is an effective and safe method, there are still doubts about its convenience.

Is it Really Worth Making a Cloud Seeding Plan?

Although cloud seeding can have an effective immediate result in producing rain, the risks are high. First, it seems like an "easy" way to wash your hands of much deeper water preservation and climate change responsibilities. As we already pointed out, it is an expensive method, the resources of which could be invested in long-term plans.

Likewise, natural processes are altered without knowing their long-term implications, which has already been shown in history that usually has poor results. On the other hand, it is still unpredictable to know how nearby areas may be affected by climatic variations. In summary, although it is a novel method that seems to be a perfect solution to drought problems, it has several "traps" that need to be weighed globally. The evidence of its effectiveness has not been conclusive, nor are the analyses of its possible consequences.