NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory (NSSL)
Not far from the Dead Dog Saloon, behind a body shop on the main street of Grantsville, Utah, stands a rusting, four-foot-tall metal box. The box sits atop a tank of gaseous silver iodide that, when fired up, sends a plume downwind toward the nearby Oquirrh Mountains. Once carried up on the wind, each silver iodide crystal forms a core, or nucleus, around which water droplets collect. Since silver iodide has a crystalline structure similar to that of ice, it allows the tiny water droplets to coalesce until they are big and heavy enough to fall out of the sky, ultimately increasing snowfall between 10 and 15 percent a year. That’s more water for later release across the state’s thirsty desert during spring and baking summer, more water for irrigation, livestock, human consumption, and sports. It means millions of dollars in water-related revenues for the state’s economy every year.
The Utah cloud-seeding effort comes courtesy of North American Weather Consultants, America’s oldest weather modification company, located in an upscale office park in nearby Sandy, Utah. Founded in the 1950s, the group is currently run by two solid-citizen scientists with commercial aims, Don Griffith and Mark Solak, who have spent their careers working in privately funded weather modification efforts around the country and the world.
In Colorado they seeded the Gunnison River drainage, a series of reservoirs and dams in the west of the state. In California they run seeding programs for the Santa Barbara County Water Agency, a group that says the effort may increase rain in target areas up to 20 percent a year.
In reality, cloud seeding is pretty low tech: A tank of silver iodide is topped by a burner and surrounded by a perforated-metal wind arrester. The whole contraption is hooked to a tank of propane to provide the flame and warmth that lifts the silver iodide into the atmosphere. ”We’ve got lots of cloud-seeding units in mountainous areas all around Utah,” Solak says. When wind, temperature, and humidity are just right, the company calls local residents, who are paid a fee to go out and turn on a cloud-seeding unit, sending a plume of silver iodide downwind. Why an array of cloud seeders? Although a single plume cannot change the world, a group of such seeders, each responsible for a small shift in precipitation, can often tilt the balance locally, driving rainfall or decreasing the intensity of storms.
“In weather modification, the uninitiated think you must make huge impacts on the atmosphere to get a desired result,” Griffith says. “But it’s actually the opposite. If we just make tiny modifications to existing conditions, little touches here and there, the changes then cascade upward using the existing weather’s natural actions, and that’s what gets the biggest results.”
While coaxing more rain or snow seems a modest achievement, projects on the drawing board might revolutionize our relationship with the elements and eliminate those tragic, weather-based “acts of God.” Imagine the ability to steer hurricanes offshore or shatter twisters, to prevent drought and heat waves, and to stop that worst of all nightmares—the melting of the polar ice caps and the flooding of coastal cities as the planet warms. The insight from weather modification’s old guard—that tiny changes can engender profound atmospheric shifts—has been embraced by more recent, cutting-edge investigators, those conceiving weather-changing satellites and using physics theories to invent a climate of choice.
“Weather systems are large, and our inputs as humans are so small you’d think we’d have no influence at all,” says Ross N. Hoffman, chief scientist and vice president of research and development at Atmospheric and Environmental Research (AER), based in Lexington, Massachusetts. Yet with the help of new, highly nuanced computer models, Hoffman is working to alter weather based on tiny tweaks in the chaotic motion of air. Already he has shown, at least on the computer screen, that small changes in wind and air temperature—in fact, no more than 3 to 5 degrees—could have redirected hurricane Iniki away from landfall in 1992 and reduced the strength of hurricane Andrew that same year. His colleagues hope to obliterate tornadoes and eliminate the scourge of drought using everything from lasers to tiny, solar-powered satellites orbiting Earth.
Efforts to change the weather seem more important than ever in this age of extremes, from killer hurricanes to furious nor’easters to ravaging floods. In 2007 alone, summer flooding in Great Britain cost that nation nearly $6 billion, while torrential rains in China displaced more than 500,000 people, with losses to property and crops in excess of $1 billion. And anyone considering recent weather has to recall the disastrous 2005 hurricane season, which birthed Katrina, Rita, and Wilma and cost the United States not only 2,280 lives but nearly $140 billion in losses. Three years later, from Biloxi to New Orleans to Houston, that destruction is still being repaired. According to the National Weather Service, the past decade was both the hottest and among the most meteorologically violent since the agency began keeping records.
When you consider that some of the most extreme weather has been driven by humans—that we have already been changing the weather, and in a negative way—the impetus to set things right makes particular sense. Our mechanized, urbanized, industrial society has burned so much fossil fuel that we have overburdened the atmosphere with carbon dioxide, pushing the earth’s elements out of balance. The greenhouse effect may be linked to hurricanes in summer and brutal storms in winter. If we cannot change the weather back, the melting of the ice caps, the flooding of our cities, and the destruction of crops may be next. If we have indeed wrecked the weather, perhaps we can set it right again.
