Cloud seeding relies on either propane burners on the ground or airplanes to add particles that cause the clouds to release moisture and increase snow packs. Illustration © Jeffrey Jane Flowers
Southern Wyoming is a good place for a rigorous examination of that dangling ambition of hope called cloud seeding. It is, like much of the West, a place of hot and cold, high and low, wet and dry. Especially dry. In a region where wetness predicts wealth, the natural state of affairs here is dry.
This dryness is evident along Interstate 80. The highway skitters across Wyoming like the winds that so frequently scour it. Little in the landscape deters travel. Even the Continental Divide, sharp as a razor’s edge in most of the Rockies, is so indistinct here that it is announced twice, in highway signs about ten miles apart. More striking yet is the absence of water. It takes little water to define the quickest way to an ocean, which is always downhill. Here, there is too little water even to force the hand of gravity.
The university town of Laramie gets only seven inches of precipitation annually, but to the west of the town the land rises swiftly. The winds sweeping up from the sagebrush plateau push the clouds onto rows of peaks—the Medicine Bow and Sierra Madre ranges. Detained briefly, the clouds drop sometimes prodigious quantities of snow on these islands of peaks, land mostly administered by the U.S. Forest Service, and then push on southwesterly toward Rocky Mountain National Park.
It is montane snowpacks such as these that are the source of wealth in the West. Truck farms of California’s Imperial Valley, the ski slopes of Utah’s Park City and the suburban lawns of Colorado Springs all rely heavily on the moisture captured in these high mountains. Small wonder that the quest of atmospheric alchemists soon after World War II became that of inducing the clouds to leave more snow.
Call them artificial inseminators of the sky. These cloud seeders claim they can, given the proper clouds, augment snowpacks by 10 to 20 percent. The most common technique is to use propane burners to loft a substance—silver iodide, most frequently, although new generations of particles are gaining favor—into the clouds as a storm approaches. More rarely, and far more expensively, airplanes can be used. With experiments going back to the 1950s, including many that employ rigorous scientific research models, the methods have at least modest credibility in the scientific community and several strong supporters in the industrial sector. Several ranges in Utah, for example, have been seeded for decades by local water conservation groups. Power companies operating hydroelectric dams in the Sierra Nevada have been funding cloud seeding for fifty years, believing that even an increase of less than 2 percent in water yields enough revenue in electrical sales to justify the cloud-seeding costs.
But despite their experiments and their degrees—many cloud seeders have doctorates in atmospheric science and related fields—the broader world tends to hold them as little more scientifically grounded than the rain and snow dancers of the aboriginal tribes. One official involved in water supply issues in Colorado jokes that ranchers and others investing in cloud seeding would do better to breed rabbits. Rabbit feet, he reasons, would cost less and provide just as much luck.
Although shy about discussing it, some of the West’s larger water providers may feel the same way. For example, Denver Water, which provides water for 25 percent of Colorado residents, sank $750,000 into cloud seeding in the immediate aftermath of drought before quietly rolling up the carpet once storms returned to near-normal. In wet cycles, cloud seeders are kept waiting in the lobby.
Yet, when drought strikes, cloud seeding is as good as religion. This cyclical pattern has been evident in Colorado. After the drought of 1976--–77, cities, ski areas and water districts across Colorado that depended on the mountain snowpack—which is to say, virtually the entire state—clamored to climb aboard the cloud-seeding wagon. Everybody was chipping in to seed clouds. Then, the big snow years arrived. In 1983, record snows melted in the Rockies, and the gush almost succeeded in Edward Abbey’s dream of cracking Glen Canyon Dam. Cloud seeding in Colorado only continued thereafter at the Vail and Beaver Creek ski areas.
Now, it’s drought time again in portions of the West—as big a drought as can be remembered. Possibly the worst in 300 years in some places, it is an epic dry spell that draws precautionary comparisons to the drought that evicted the ancestral Pueblans from their cliff dwellings at Mesa Verde 800 years ago. Although a big winter in the Southwest smoothed the brittle edge there, the residual fear from Denver to Boise to Phoenix is that the recent past is a hard look at the future.
This jitteriness is putting money into the pockets of cloud seeders and leading to larger, more methodical experiments. In some cases, it’s like a lucky sock that the baseball slugger cannot bear to change, for fear that it will break the hitting streak. That seems to be the story in Gunnison County, Colorado, a place well known for its high-elevation (8,000 feet) long-distance runners, its double-black-diamond skiing at Crested Butte and its still-uncluttered stock ranges.
The Utah-based cloud seeder North American Weather Consultants took credit for 18 percent of the 30 percent increase in water yield from last winter’s snowpack. There is no way that claim can be verified, as it was not a double-blind experiment, but the ranchers and skiers are afraid the company just might be right. “I don’t know if it works or not, but I’m afraid to not fund it and then find out it had been what gave us our snow,” says one stockman. This year, a coalition of towns, ski area interests and stockgrowers will foot the bill of $92,500 for continued cloud seeding. For those who might forget what drought does, there is always the sight of dying aspen trees in the Gunnison National Forest, residual casualties of drought.
On a much larger scale, there are also calls from both local government and private interests for the federal government to get involved again. From the 1950s to the early 1980s, the federal government spent up to $20 million a year on weather modification. Lately, the funding has dropped to about $500,000 a year.
During the drought, the seven states of the Colorado River Basin saw the icon of hydrological ingenuity, Lake Powell, approach the usefulness of an empty bathtub. While the bathtub began refilling after last winter, the states began to fully realize the insufficiency of the elaborate plumbing of the Colorado River system in the face of both drought and the rapidly growing population of Sunbelt cities. “Something’s got to give,” says Don Ostler, executive director of the Upper Colorado River Commission.
From the perspective of the seven states from Wyoming to California, the solution lies in augmenting the supply. They see desalinization and ridding the rivers of thirsty tamarisk, an invasive species, as being among the low-hanging fruit. Cloud seeding is another easy option.
Speaking from his office in downtown Salt Lake City, the Wasatch Peaks rimming the valley, Ostler explains that the states see no need to prove that cloud seeding works. They believe it does. At issue are the effectiveness, the cost and the secondary impacts.
“I don’t think the states are starting from the point that they want to do research to decide if it can enhance snowfall,” says Ostler. “I think the states have the position that it can enhance snowfall, and the question is whether it can be used in portions of the basin to enhance snowfall.”
The broad issue of secondary impacts is a ticklish one. For example, consider the cloud seeding experiments done in the winter of 1978–79 near Steamboat Springs, Colorado. It was, as ranchers thereabouts say, a three-wire winter. Snowfall by January was nearing the top of the pasture fence posts. The cattlemen, growing ever more weary of bucking bales of hay through deep snow, began to complain loudly. Why should they have to work harder because of cloud seeding, they asked. A few also pointed to dead magpies that they alleged were dying from the chemicals being used for cloud seeding, although tests later revealed the birds had gotten into poisoned grain in one of the ranchers’ sheds.
Some years later, another complaint was voiced from Leadville, an old mining town south of the ski resort of Vail. It was another big year, and the residents of Leadville were sure that they were spending more money plowing streets because of cloud seeding at Vail some 20 miles (as the crow flies) away. Such issues of blame—and credit—have never been fully addressed, despite the claim of cloud seeders that they are increasingly able to target where the artificially induced snow falls.
It’s not hard to imagine another scenario, that cloud seeding caused the added snow that finally overloaded the slope, causing an avalanche that—well, you fill in the blank.
A broader complaint is that fleecing clouds of moisture in one place robs downwind areas of that moisture. “If you make the clouds rain somewhere, the laws of physics dictate that the water can’t go somewhere else,” Charles Doswell, a severe-storms meteorologist with the University of Oklahoma, told one interviewer. “You have this problem of robbing Peter to pay Paul.”
Arlen Huggins of the Reno, Nevada–based Desert Research Institute argues that the downwind effect is minor. Only 10 percent of the water vapor in a typical storm is suitable for seeding, he says, and then seeding can only augment by 10 to 20 percent. As such, he says, cloud seeding only reduces the water in clouds going downwind by 1 or 2 percent.
The Colorado River Basin states are reviewing studies in order to decide whether to plunge ahead with a broader, basin-wide approach to cloud seeding. At first blush, says Colorado’s representative to the commission, it would appear that cloud seeding is a “real opportunity for inexpensive water.” But whether or not cloud seeding is the answer, he adds, what is clear is a “greater urgency” to the attempts to augment supplies.
That greater sense of urgency is also apparent in a proposal before Congress that would make the federal government the team leader once again in weather modification. The bill, submitted by Senator Kay Bailey Hutchison, a Republican from Texas, and Representitive Mark Udall, a Democrat from Colorado, would create a Weather Modification Advisory and Research Board to oversee disbursement of $10 million annually for the next decade. Some of the thinking behind the proposal is that while the states pay for cloud seeding intended to produce snow, the federal government should oversee the purer science, such as experiments. The greatest uncertainties, scientists say, have to do with timing of seeding relative to cloud systems and the precision of targeting.
“Weather modification is not some kind of weird science,” insists Udall’s press secretary, Lawrence Pacheco. But more fundamental research is needed to understand and improve weather modification technologies, he says. Because of Western drought and hurricanes, he added, there’s a good chance the bill will advance this session.
Wyoming, meanwhile, isn’t waiting for the federal government. The state legislature has authorized spending almost $9 million during the next five years. The money is to both test the proposition as to whether cloud seeding works, laying the possible foundation for a long-term program, and also to provide snow.
Ranchers in the southwest corner of the state called for the program after the drought-singeing summer of 2003. LeRon H. Allred, a farmer–rancher from the Salt River Valley, remembers water shortages began weeks early, in some cases causing 50 percent reductions in the hay and barley crops. But far more striking was the withering scene near Rock Springs. “You could look across the prairie, and it was brown, and there was no vegetation higher than a half- or a quarter-inch,” he says. “It was total devastation for those folks down there.”
If Idaho and Utah had cloud-seeding programs year after year, the stockmen reasoned, they must work—why else would they keep doing them? Or, at least, it can’t hurt. “Cloud seeding is one of those fire-insurance policies,” says Allred.
The program now planned is to seed clouds pushing over the Salt River Mountains near where Allred lives and the Wind River Range. But the most ambitious project is in the Sierra Madre and Medicine Bow ranges.
The work in southern Wyoming will be organized in a way to help answer the questions: Does it work? and, just as important, When does it work? Cloud-seeding scientists say that a storm improperly seeded can actually reduce the snowfall, not augment it. Furthermore, although clouds are essential for seeding, the productivity of those clouds ranges on something of a bell-shaped curve.
Seeding in these Wyoming ranges will be done in scientifically rigorous fashion. Some clouds will be seeded, and others not. There will be placebo particles in some generators, the real stuff in others. Effects of seeding storms will be predicted, and then measured for effectiveness. Computer modeling—a major advancement in weather modification—enables precision.
The goal is to “try to pull out a signal from the natural range of variability,” explains Dan Breed, an atmospheric scientist with the National Center for Atmospheric Research, which has been retained to structure the experiment. Doing so is virtually impossible in one season, given the almost infinite range of possibilities within clouds, he says. “Wyoming is a little bit on the leading edge of doing this in a well-measured way,” he adds.
If the cloud-seeding experiment does what many hope it will do, the North Platte River will carry more water most years, providing a bigger cushion for ranchers and also officials in Casper and other cities. The problem, explains Bill Vasey, a state senator from Rawlins, is that there just isn’t enough water for everybody in some ways.
The river, he says, has three good reservoirs, but Wyoming—and also Colorado—are obligated to release enough water to meet the needs of sandhill cranes and other birds in Nebraska. As such, most of the water is already spoken for. “One of the reasons we are looking at cloud seeding in this drainage is that if we can increase the snowfall amounts, even if only 10 to 15 percent, that would help go a long way toward answering that call from downstream for water.”
Because the cloud-seeding generators are to be placed on the Medicine Bow National Forest, the Forest Service must issue a permit after first conducting an environmental analysis. Elsewhere, the agency has been passive as winter cloud-seeding activities aim to increase snowpack on higher, public lands. It does note that “rigorous scientific analysis” has found that cloud seeding in the Sierra Nevada augments snowfall by 2 to 10 percent—much lower than the typical claims of cloud seeders.
Cloud seeding remains little more than a footnote, something even other scientists tend to dismiss. Joe Golden, who recently retired from the National Oceanic and Atmospheric Administration after forty-one years, many of them in weather modification, finds a double standard. Medical researchers are not required to prove to a 95 percent confidence level that a new drug will work before it is approved for public consumption, yet detractors raise the bar higher for cloud seeding, he says. Similarly, the theories of global warming—which he subscribes to—are not held to the same high bar as cloud seeding. “Many of us feel they have applied two standards, one for weather modification, and another for global warming.”
“A lot of water managers are happy with a 90 percent confidence on a 10 percent increase in water,” says the Desert Research Institute’s Huggins.
Roger Pilke Sr., the Colorado state climatologist, believes that claims for weather modification have been oversold, but he believes that cloud seeders have credibility. “There are some excellent scientists working in the area,” says Pilke, who argues for more hard, rigorous science to further verify the claims and the contexts for those claims.
But a bigger issue might be the question of appropriateness: Even if cloud seeding can rob the clouds of moisture, and even if it seems to be to our greater benefit, should we employ that technology? As a species, we’re often taken with our own ability to tinker with nature. Many claims have been made in the name of science, and certainly we’re willing to accept many— perhaps nearly all—of them. Anybody want to forego their flu shots just to test the prowess of the annual dose of microbes? How about abandoning mosquito repellent?
But from dousing trees with poison to inundating canyons, we’ve gone overboard in our attempts to manipulate nature. The idea that we can substantially modify our hydrological regime over broad areas, coaxing more snow from clouds, could be just one more of those tools that, in the final analysis, is best when used sparingly.