Mexico cloud seeding against drought, but experts have many doubts

The severe drought that has hit Mexico has led the government to think of various solutions to deal with the emergency

by Lorenzo Ciotti
Mexico cloud seeding against drought, but experts have many doubts

The severe drought that has hit Mexico has led the government to think of various solutions to deal with the emergency. Defense Minister Luis Cresencio Sandoval is thinking about cloud seeding, a technique which consists in the dispersion of chemical substances in the clouds to favor rainfall.

According to the government, this technique has so far been 98% effective in increasing rainfall. However, the decision of the Mexican government has the negative opinion of the scientific community. Physicists from the Mexican university National Autonomous University of Mexico, Fernando García García and Guillermo Montero Martínez explained: "There is no evidence that cloud seeding techniques allow the increase of rainfall over important economic zones, nor is there any certainty about the effects outside the target zone.

Artificial weather modification should only be considered as one element of an integrated strategy for the management of water resources." The president of the Mexican growers' association, Álvaro Bours Cabrera, added: "We are skeptical.

We would prefer the government to invest in water distribution networks and increase water recovery systems."

Cloud seeding in the USA

In the United States, cloud seeding is used to increase precipitation in dry areas and to reduce both the size of hailstones that form in thunderstorms and fog at airports.

It is also occasionally used by major ski resorts to induce snowfall. Several commercial companies, such as Aero Systems Incorporated, Atmospherics Incorporated, North American Weather Consultants, Weather Modification Incorporated, Weather Enhancement Technologies International, and Seeding Operations and Atmospheric Research offer weather modification services focused on cloud seeding.

The 1960s Project Stormfury was an attempt by the US military to modify Atlantic hurricanes. It is unclear whether the project was a success, as only a few hurricanes were tested with cloud seeding due to strict restrictions set by the project's creators.

Furthermore, the minor structural changes of the hurricanes were temporary. The fear that cloud seeding could alter the direction and strength of hurricanes and have negative effects on the population led to the abandonment of the project itself.

Since the 1960s, two federal agencies have supported various weather modification research projects: the US Bureau of Environmental Remediation, a branch of the Department of the Interior, and the National Oceanic and Atmospheric Administration of the Department of Commerce.

The former sponsored research projects from 1964 to 1988 including them in the Skywater project, while NOAA conducted a weather modification program between 1979 and 1993. The projects have been exported to several states, and two countries (Thailand) are currently studying the possibility of modifying the weather in both summer and winter.

Between March 1967 and July 1972, the US military, during Operation Popeye, seeded North Vietnam, specifically the Ho Chi Minh Trail, with iodized silver in order to prolong the monsoon season. Following this operation there was an extension of the rainy season between 30 and 45 days.

Although the United States later signed the ENMOD Convention, which prohibits the use of weather modification techniques for hostile purposes, a 1996 US Air Force study reverted to speculating on the use of weather modification methods in the military.

More recently, a small-scale research project by six western states called the Weather Damage Modification Program was presented between 2002 and 2006. In January 2006, $8.8 million was earmarked for cloud seeding programs in Wyoming to test the technique.