MAKE IT RAIN

Brazil’s drought last year killed 23 percent of its coffee crop. Since 2000, droughts have impacted one person in every five on the planet and cost more than $125 billion in economic damage.
About 60 percent of the continental U.S. is in a drought right now, according to the National Oceanic and Atmospheric Administration. Lake Mead, which sits behind Hoover Dam and distributes water to millions of homes, farms, and other businesses in Arizona, California, Nevada, and New Mexico, is 40 percent below its capacity, triggering discussions among the four states about how they can cut water usage to stave off even worse conditions downstream.
The U.S. drought has been especially severe in the Northwest, where Idaho Power, a utility sending electricity to a half-million customers, has relied on a controversial, 75-year-old technology to make water: cloud-seeding.
Over the past several winters, the company has flown planes over the Owyhee and Sawtooth mountain ranges to drop flares into clouds. As the flares burn, they release silver iodide crystals. 
The crystals attract water molecules, which clump into ice crystals that fall as snow on the mountains. 
In spring and summer, the snow melts, making water that builds up behind river dams to drive the utility’s hydropower production.
Cloud-seeding has been around for 75 years and has been a topic of debate for almost as long.
However, the results of a 2017 study published last year settled the question.
The National Center for Atmospheric Research, Idaho Power, and a group of universities seeded clouds over Idaho’s Payette Basin and gathered data showing that ice crystals formed following the planes’ exact paths.
Over this past winter, Idaho’s Water Resources Board funded an additional study in the state’s southeastern Bear River Basin. 
Colorado had been seeding clouds by plane along its northern border with Wyoming to make snow for its ski resorts and has now tested ground-based silver-iodide generators. When winds sweep up the mountainsides, the generators are turned on and the winds carry the crystals up into the clouds.
As a result, the state’s Jackson County Water Conservancy District recorded a snowpack holding a billion more gallons of water than the annual average.
TRENDPOST: With droughts and food shortages becoming more common, so will cloud seeding. Studies show the amount of silver used in seeding is not enough to be environmentally harmful. 
TREND FORECAST: Studies have largely settled the question of whether cloud-seeding works, even if the results are often modest, and public officials are looking ever more desperately for answers to drought.
However, silver to make silver iodide is a depletable resource and its price is rising.
Researchers will take a second look at replacing silver iodide with dry ice—frozen carbon dioxide—the original material used to seed clouds in the 1940s when the idea first was tested.