Cloud seeding unproven, but many buy it

For 31 years, Larry Hjermstad has been making snow in the skies over Colorado’s mountains.

Or has he?

He’s manager of Durango-based Western Weather Consultants, and his cloud-seeding equipment pumps silver iodide particles into the air around ski resorts and high mountain basins, ostensibly aiding the process by which icy crystals in clouds turn into snowflakes.

There’s a flurry of interest lately in cloud seeding in Colorado. Ski resorts and water suppliers — including Colorado Springs Utilities — will spend an estimated $900,000 this winter, more than ever before, on the technique. And for the first time, Arizona, Nevada and California — downstream states in the Colorado River Basin — are contributing large amounts of money to Colorado efforts.

All for something that many weather experts say doesn’t work, and that even advocates agree needs more research.

Hjermstad, though, has no doubt.

“We have research information that can substantiate this,” he said. “It just depends on whether you want to look at this with an open mind or a fixed opinion.”

Cloud seeding occurs from Nov. 1 through April 15 in eight counties in the central mountains. When a snowstorm hits, residents who work as contractors for Hjermstad turn on cloud nuclei generators, which melt silver iodide and send the particles aloft.

A snowstorm has to be in the area, and the silver iodide causes cloud moisture to freeze into ice crystals, which enlarge and fall as snowflakes. In theory, seeding can make a storm drop up to 8 percent more snow.

It began in the 1970s as a tiny operation to improve the skiing at Vail. Aside from a brief increase during a late-1970s drought, it remained a small, localized effort until 2002. That was the year of the Hayman fire and the zenith of a paralyzing drought.

In the years since, the state’s major water suppliers have gotten involved. Utilities allocated $80,000 in 2002 for cloud seeding, and last winter spent $115,000.

This year, the Colorado Water Conservation Board awarded $150,000 in grants for cloud seeding, up from just $20,000 in 2004. Three other states contributed $135,000.

Joe Busto, who oversees cloud seeding for the board, said the procedure has come a long way from the days when companies were regarded as snake oil salesmen.

“When people start to look around and see there are 10 states in the U.S. doing this, and many countries, you start to accept it more,” Busto said.

“It’s not the answer to population growth or climate change, but I believe it does help,” Busto said.

But he acknowledged its benefits are tough to prove.

“You can’t make any large, robust claims about it,” Busto said, “and if you do, how do you back them up?”

That’s the question weather and climate experts have been grappling with for decades.

In 2003, a National Academies of Science report concluded that there is no convincing evidence cloud seeding works.

Supporters found some hope in the report, however.

“In some instances there are strong indications of induced changes,” it said, “but this evidence has not been subjected to tests of significance and reproducibility.”

Research into cloud seeding has all been too brief or too localized, hampered by a lack of funding. Though lab testing shows the process does make snow, how much impact it has on a mountain — especially considering the variations between winters each year — is up in the air.

Colorado State University climate researcher Bill Cotton conducted one cloud-seeding study five years ago. A $100,000 grant to study weather modification in Colorado produced no definitive results.

He said there is a “good chance” cloud seeding boosts snowfall, adding that to have so much spending on it without conclusive research is “kind of sad.”

“It’s not a very effective way to do science,” he said.

Supporters and skeptics hope a congressional bill introduced by Colorado U.S. Rep. Mark Udall to provide $110 million for weather-modification research is approved this session, to finally reach an answer in this debate.

For Colorado Springs Utilities officials, the debate is over.

Budget concerns forced the utility to scale down its seeding program to $65,000 this winter, but engineer Kevin Lusk said seeding has added 3 to 11 percent to snowpack in the high mountain basins that provide the city with its water.

“It’s worth it for us,” he said. “Even if it was a quarter of the efficiency, we think it is still cheap water.”