Modifying the weather is becoming an increasingly attractive option for the western US as key reservoirs in the Colorado River system sink to record lows. A new $2.4 million grant from the US Bureau of Reclamation aims to expand the controversial water-making technology of “cloud seeding” in key parts of the Upper Colorado River Basin.
The government funding will be received by the Southern Nevada Water Authority and used to support cloud seeding programs in other Western states whose river flows supply Nevada, including Colorado, New Mexico, Utah, and Wyoming. Most of the money is expected to go toward upgrading existing manual generators to ones that can be operated remotely, as well as planes used to deliver “seeds.” Currently, the programs are funded by a pool of various groups.
For those not familiar with cloud seeding, the practice involves spraying special particles into the air in order to boost rainfall. The most common chemical used for the process is silver iodide, though other kinds of salt particles and even dry ice are also used. Silver iodide particles have a structure similar to ice. When introduced to clouds, water droplets cluster around the particles and can increase the chance of precipitation. The particles can be dispersed via seeding “cannons,” or generators, as well as by drones and aircraft. Some, including researchers at the USDA, are investigating the use of electrical charges.
Cloud seeding has been used for decades with varying degrees of success but has seen a recent boom in interest amid severe droughts and changing climate patterns that threaten to leave some parts of the world with inadequate fresh water supplies. Compared to other water-generating strategies, such as desalination, it is a relatively affordable option.
The United States Bureau of Reclamation and the National Oceanic and Atmospheric Administration (NOAA) have both supported weather modification research projects in the past. Funding mostly dried up since the early 2000s though as questions about the efficacy of cloud seeding and possible environmental consequences were raised.
According to Frank McDonough, a scientist at the nonprofit Desert Research Institute, new research over the last decade has made a convincing argument for the efficacy of cloud seeding. Studies show the practice can boost precipitation from storm clouds by +5% to +15%. Most recently, research last year was able to quantify the amount of snowfall generated by employing cloud seeding. The total amount of water generated in the three studied cases ranged from 1.2 × 105 m3 (100 ac ft) for 20 min of cloud seeding, 2.4 × 105 m3 (196 ac ft) for 86 min of seeding to 3.4 x 105 m3 (275 ac ft) for 24 min of cloud seeding.
Experts warn, however, that cloud seeding is not a cure-all for drought and can also be difficult to implement. Only certain types of clouds in specific weather conditions are ripe for seeding. Meaning the practice would be useless in a region experiencing conditions that generate no clouds. Outside temperatures also need to be cold, which would make the practice ineffective in many areas experiencing systemic drought or desert climates that stay too warm.
Still, many say the ability to even marginally increase Western water supplies could make a big impact if managed efficiently. Western states primarily use it to boost snowpack which in turn feeds the Colorado River system as it melts in the spring.
The practice may carry inadvertent risks, too. One of the concerns is the cumulative public health and environmental effects of chemicals used in the process. Another is the potential danger of taking rain away from an area that might need it more, or drying the air faster than it’s able to rehumidify, resulting in subsequent years of droughts and/or fires. At the other end of the scale, there is also the potential for creating floods, either from seeding too much or from strong winds that carry seeded clouds further than expected. (Sources: Associated Press, American Rivers, Colorado Sun)
