With a severe drought parching Colorado and much of the American West in recent years, Denver’s water department decided to take a gamble in the hope of squeezing more precipitation out of the atmosphere. It has invested more than $1 million in cloud seeding in the last two years.
Has it paid off? Possibly, some research suggests.
The most recent report, issued Monday by the National Research Council, is inconclusive.
“Evaluation methodologies vary but in general do not provide convincing scientific evidence for either success or failure,” says the report, titled “Critical Issues in Weather Modification Research.”
“Although there is physical evidence that seeding affects cloud processes, effective methods for significantly modifying the weather generally have not been demonstrated,” it adds.
Prepared by an arm of the National Academies, it acknowledges the potential benefits of cloud seeding, designed to wring as much moisture as possible from some storms by adding certain chemicals to existing clouds, and recommends additional research.
Chips Barry, the Denver water department manager, is a believer, of sorts.
“I have a reasonably based belief that it works,” he said. “It’s not the sort of thing where I’ll swear that it works. But until our reservoirs are back where they should be, I know I will recommend it again to our board.”
The water board approved his latest recommendation this month, allocating an additional $400,000, bringing the total to $1.1 million in two years.
Al Cooper, a cloud physicist and director of the Advanced Study Program at the National Center for Atmospheric Research, said the benefit could be substantial for a fairly small investment. “Even if it’s wrong,” he said, “it’s like buying a lottery ticket where not much investment might pay off big.”
Seeding also is cheaper than buying water rights or stored water.
Still, said Craig Roepke, the director of the New Mexico Interstate Stream Commission, even people in the cloud-seeding business differ over many aspects of it.
“They’re not in agreement on technique, and they’re not in agreement on the result,” he said.
Roepke added, however, that cloud seeding shows “a great deal of potential.”
The National Research Council report noted that 66 similar projects were under way in the United States as of 2001, in addition to those in 24 other countries.
