As mountain snowpacks have become increasingly hit or miss in the western US, everyone from power companies to ranchers and farmers to recreational boaters have felt the effects.
The problem is that precipitation across much of the western US is highly seasonal. The majority of water falls as snow in the mountains over the course of just a few months in the winter. That snowpack then provides water to the dry lowland regions as it melts throughout the spring and summer. As climate change continues to diminish snowpacks relative to their historic levels, there is an increasingly higher chance of water shortages and fires throughout the West during ever hotter and drier summer seasons.
To combat chronic water shortages in the western US, scientists are looking to an old idea: seeding clouds to produce more snow. Cloud seeding depends on the fact that while snow normally forms in clouds at around 10 degrees, spraying particles of silver iodide from a plane as it flies through a water-laden cloud can cause snow to form at temperatures as high as 20 degrees. The result is that scientists could potentially squeeze more snow out of clouds than would otherwise fall during increasingly warm winters.
Cloud seeding originally gained popularity and funding in the 1980’s, but lost steam as scientists were never able to convincingly prove that their tests were working. But last winter, 18 tests across Wyoming demonstrated conclusively that cloud seeding can effectively increase the amount of snow falling from the sky. The upshot is that several western states are banding together to fund a potentially long-term cloud seeding program across the Colorado River basin.
However, don’t expect scientists to suddenly coax tens of feet of snow out of the sky. Cloud seeding remains prohibitively expensive on a scale the size of the entire western US. More important, seeding clouds only helps to draw out moisture that’s already there – during drought years, when clouds are relatively dry, the effectiveness of cloud seeding is likely to be limited in pulling more water from the air.
Even if cloud seeding isn’t a complete fix for the West’s water shortages, it may help quench the western US’s thirst.