Battling Global Warming

With persistent droughts and concerns over global warming heating up, cloud seeding is a growth industry. Some resorts swear by it. Others aren't so sure.
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With persistent droughts and concerns over global warming heating up, cloud seeding is a growth industry. Some resorts swear by it. Others aren't so sure.
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When a Colorado blizzard blows into Vail, Beaver Creek, or Crested Butte, most skiers grab their boards and head for the slopes. Not Larry Hjermstad. He holes up in front of a computer and analyzes satellite weather data, wind speed, temperate, and atmospheric moisture content. When he spots the ideal storm conditions, Hjermstad grabs the phone and orders field technicians to fire up propane burners scattered on remote mountainsides upwind of ski resorts. His mission: to increase snowfall.

Hjermstad, president of Western Weather Consultants in Durango, Colorado, is an expert in the obscure field of cloud seeding – in which silver iodide particles are injected into clouds to increase precipitation. Hjermstad and other proponents say seeding can boost snowfall in targeted areas by up to 15 percent. The scientific community remains unsure.

Vail Resorts CEO Bill Jensen is a believer. Vail has worked with Hjermstad for more than 30 years and pays him about $150,000 for a three-month seeding program that runs November through January. Hjermstad operates 17 ground-based generators located 15 to 30 miles from the resort. He activates them when he sees storms tracking in from the north or northwest – roughly 15 to 20 times per winter. Seeding squeezes an extra few inches of snow out of each storm and adds about four feet to winter totals at Vail and Beaver Creek, Jensen says. "We truly believe it works, especially for the Back Bowls, where we don't make snow."

Cloud seeding – part of a growing field known as weather modification – is one of the ski industry's tricky little secrets. Invented in the 1940s by General Electric researchers, cloud seeding has fallen in and out of favor throughout the years. Now, new concerns over global warming and shrinking mountain snowpack are making cloud seeding a growth industry again. At least 43 programs worth a combined $15 million are underway in 11 Western states. Worldwide, 37 countries are experimenting with it, with China and Saudi Arabia investing heavily.

In the U.S., water agencies and hydroelectric power producers are the biggest spenders. Ski industry cloud seeding, by contrast, remains "just a drop in the bucket," says Joe Busto, who oversees state permitting in Colorado.

Vail, Beaver Creek, Durango, and Crested Butte, in Colorado, and Alta and Snowbird, in Utah, are the only resorts that seeded last season, according to industry officials. That could change as state water managers look to partner with Western ski resorts. "This could help ski areas to increase revenues and help us fill reservoirs," Busto says.

As with Hollywood starlets and plastic surgery, cloud seeding is a topic that some resorts would rather not discuss, letting the results speak for themselves. In Utah, which boasts "the Greatest Snow on Earth," cloud seeding remains in the shadows. "Who knows whether the dang stuff works?" says Alta president Onno Wieringa. "We do it, along with snowmaking, in the early season to help build a base," says Snowbird spokeswoman Laura Schaffer. "In this state, it's not on the top of the list of talking points."

Though airplanes are sometimes used to seed clouds, most seeding is done with ground generators, which work like giant incense burners, emitting invisible plumes of silver iodide particles, which mimic ice crystals, promoting the formation of snowflakes.

But cloud seeding isn't Harry Potter's magic wand. It won't create snow from blue skies, for instance, so it's useless in a drought. Rather, it increases the "precipitation efficiency" of storm fronts, says Tom DeFelice, an executive with the Fresno, California-based Weather Modification Association. The idea is to maximize the storms when they are overhead.

The placement of ground generators is crucial. "Geographically, we're in a perfect place to utilize seeding at Vail and Beaver Creek," Jensen says. Sister resorts Breeckenridge and Keystone do not cloud-seed because the geography doesn't work.

Uncertainty about the effects of seeding remains a hurdle to wider use. "Does is add 10 percent or one-tenth of one percent?" asks Roark Kiklevich, mountain manager at Crested Butte. Jensen, however, says an internal study showed that Vail received up to 20 percent more snow from seeded storms than non-seeding resorts. "It's clear that well-targeted regions have shown enhanced snowfall," says Dan Breed of the National Center for Atmospheric Research in Boulder, Colorado. "It gets a lot trickier when you scale it up to a large area."

- SKI MAGAZINE, SEPTEMBER 2007

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