[Reading Science] "Artificial Rain for Wildfire Suppression" Government's Self-Praise Met with Scientists Saying "Rain Falls as It Will"

Mexican Government Pushes Artificial Rainfall Program Amid Severe Drought
Scientists Skeptical of Effectiveness... "Unverified, Concerns Over Budget Waste"

Extreme weather phenomena such as droughts and wildfires are intensifying due to global warming. As one of the response technologies, 'artificial rainfall' is being actively developed. However, since its exact effects have not been scientifically verified, the implementation of artificial rainfall programs in some countries has become a subject of controversy, including budget waste.

According to the international academic journal Nature on the 1st (local time), the National Dryland Commission (Conaza) under the Ministry of Agriculture and Rural Development of the Mexican government announced plans in March to implement an artificial rainfall program in the northeastern and northwestern regions of Tamaulipas and Baja California states, which are suffering from severe drought. Theoretically, silver iodide crystals have a structure similar to ice. They attract surrounding water molecules, eventually causing them to fall to the ground as rain. The Mexican government has decided to proceed with the program based on some experimental results showing a gradual increase in precipitation beyond predictions due to artificial rainfall.

However, scientists are skeptical about the Mexican government's plan to sprinkle silver iodide crystals into clouds to induce rain. Fernando Garcia, a climate physics professor at the National Autonomous University of Mexico, stated, "There is no evidence that artificial rainfall experiments succeed every time," and added, "No one knows whether it will increase or actually decrease the amount of rain."

In fact, neither the Mexican government nor the companies conducting the projects have provided convincing scientific evidence of increased precipitation due to artificial rainfall. Since 2019, the company has conducted five artificial rainfall programs, claiming in reports that there was a 98% probability of helping to alleviate drought and that they achieved effects such as extinguishing 25 wildfires and securing water resources. The Mexican government also evaluated the program as successful based on the fact that more rain fell than the forecasted precipitation in the area. The U.S. National Center for Atmospheric Research conducted three artificial rainfall experiments during the winter of 2020, observing ice crystal growth and snowfall effects, and reported triggering snowfall equivalent to filling 300 Olympic-sized swimming pools over an area of about 2,000 km².

However, scientists criticize these evaluations as "unscientific." First, using prior weather forecasts as a measure of success for artificial rainfall programs is inaccurate because no one can provide perfect rainfall forecasts. Also, rain that would fall regardless will fall even without sprinkling silver iodide powder into clouds. Even within the Mexican government, opposing opinions exist. The Scientific Advisory Committee of the Mexican National Civil Protection System recommended last year that Conaza should not implement artificial rainfall programs without detailed reviews such as cost-benefit analysis, environmental impact assessments of silver iodide, and technical verification of increased precipitation. The committee warned, "Spending resources on weather modification programs with unproven hypotheses of increased precipitation will cause economic losses to large regions and state and federal governments."

Sarah Tessendorf, a climate physicist who conducted artificial rainfall research at the U.S. National Center for Atmospheric Research, also advised that artificial rainfall is not a solution to drought. She pointed out, "To start artificial rainfall by seeding clouds, there must first be clouds and storms," and added, "To accurately measure the effects of artificial rainfall, it is necessary to conduct statistical analysis over several years or even decades under the same conditions by seeding clouds in some areas to induce rain and not seeding in others, then comparing the results. Another method is to analyze the effects using recently developed computer modeling."

Conaza has not responded at all to such criticisms. In 2021 alone, Conaza spent about 15 million pesos (approximately 363 million KRW) on artificial rainfall programs. They stubbornly insist that the program was successful because it produced rain sufficient to supply about 3 million cubic meters of domestic water.