Cloud seeding is some sort of great proof in the indomitable human spirit, or at least the bliss of uncertainty and ignorance. Water suppliers, ranching associations, ski resorts, and even Olympic host nations regularly spend millions of dollars sending silver iodide crystals into the sky with the prayers that the practice will increase precipitation. The technology has some theoretical scientific merit, but its effectiveness remains dubious and unclear.
Consider the words of Kay Brothers, the deputy general manager of the Southern Nevada Water Authority, as quoted in an October 16 article in the Las Vegas Review-Journal:
“It’s hard to quantify if (the snow) would have fallen anyway or not,” Brothers said.
But though cloud seeding “is not an exact science by any means,” it is still a pretty good investment, she said. “It’s very economical to do this.”
Despite the lack of measurable evidence, the water authority recently chose to continue its long-running cloud seeding program, approving the use of about $900,000 over the next three years to try and boost mountain snowpacks.
In early 2006, I wrote a feature, “Snow Job,” on cloud seeding efforts in Colorado for the Rocky Mountain Bullhorn and the Colorado Springs Independent. Here’s a short excerpt:
“It’s clear that water is scarce in the West,” says NCAR’s [Dan] Breed. Cloud seeding should be “one of the pieces in the watershed management tool-chest.”
Breed adds that projects like the one in Wyoming could convince Arizona, Nevada and California to invest in large-scale cloud seeding in upstream states, to the benefit of everyone who relies on the Colorado River for water.
Colorado State professor William Cotton says a regional seeding program could increase precipitation 8 to 10 percent throughout the river basin, but he admits that’s “just a guess.”
“The question is, just how much can cloud seeding do to enhance snowpack?” says Cotton, sitting in his office on Colorado State’s Foothills Campus. “I don’t know the answer to that, as a scientist.”
The uncertainty looms like a thunderhead for environmentalists and others. Critics worry about the environmental and health effects of silver iodide falling from the sky and trickling into the reservoirs. They wonder whether cloud seeding boosts one location’s precipitation while depriving another.
“If you’re cloud seeding in one area, does that mean you’re taking away from another area?” asks Andrea Ray of NOAA.
Jennifer Pitt, a scientist with Environmental Defense in Boulder, says expectations that seeding will prevent drought and cultivate new development in the West are disturbing. She says research has demonstrated only that weather modification might shift where rain or snow falls, not increase the available moisture.
“I’m somewhat concerned that [cloud seeding has] become a basin-wide approach,” says Pitt. “By focusing on this, rather than a more practical approach of conserving water, [the states of the Colorado River Basin] are shifting emphasis on this critical issue.”
I wrote another feature, “The Why of the Storm,” about weather modification and the possibility of controlling hurricanes for the Rocky Mountain Chronicle in 2007.
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