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Monday, June 9, 2008

Harnessing the Weather

Could new technology help humans eliminate "acts of God"?

by Donovan Webster
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.

NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory (NSSL)

Changing the weather has been a scientific quest since the 16th century, when rogue intellectual Leonardo da Vinci asked the city fathers of Verona to shoot cannon­balls skyward to halt the hail. But it wasn’t until after World War II, at the improbable site of the General Electric Laboratory in Schenectady, New York, that a plan went into effect. In the beginning, a team that included atmo­spheric scientist Bernard Vonnegut (brother of novelist Kurt) sent up a plane and released dry ice into clouds on four days during November and December 1946. Whether by coincidence or through actual impact, the last day of seeding saw the heaviest snowfall of the winter around Schenectady. Vonnegut went on to invent what amounted to a nucleating machine: He dissolved silver iodide in acetone, sprayed the solution through a nozzle to make droplets, and then literally burned the droplets, producing trillions of nuclei; under the right conditions, each could form the core of a drop of water or flake of snow. But General Electric, wary of potential lawsuits, gradually moved away from direct involvement in weather research.

By the 1960s the U.S. military had taken the reins. Its effort, called Project StormFury, aimed to weaken hurricanes by seeding their upper reaches with silver iodide crystals, nucleating agents that would increase the amount of ice swirling around in the storm. The idea was that as water became ice, it would release heat. The heat, in turn, would widen the eye of the storm and decrease the strength of its winds.

Unfortunately, StormFury’s statistical findings were ambiguous. While human manipulations did sometimes seem to weaken hurricanes, test flights into the storms never provided proof. “What we didn’t know at the time,” says Charles Hosler, professor emeritus of meteorology at Penn State University and former StormFury panel chairman, “is that measuring the forces inside hurricanes is far more complex than what was possible with the equipment of the time.”

The shuttering of StormFury in 1983 signaled a new age of skepticism and the end of major federal funding for weather-control research. Indeed, while many practitioners pointed to statistical evidence suggesting their techniques worked, it was usually impossible to prove it; one could never precisely predict what would have happened had the intervention not taken place. Amid such doubt, the federal government backed off, and weather modification became the province of private companies and local municipalities.

Some of these efforts have thrived. Less than an hour’s drive from Grantsville is one of the most successful and scientifically validated weather-modification operations in the world. The wizard behind the curtain is Richard Blair, CEO and chief bottle washer of Barken Fog Ops, a fog-abatement company in Salt Lake City. The company’s mission: to expunge the crippling cold fogs at Salt Lake City International, which would otherwise shut the airport down. The fogs visit from October to March, anytime a stubborn pool of cold air settles across the Salt Lake Valley between the Wasatch and Oquirrh mountains. Whenever a front of warmer air sweeps over the frigid pool, the result is a fog that hovers roughly 1,000 feet aboveground, socking the airport in.

The first, tiny effort to deal with the problem took place decades ago, when pilots distributed buckets of ice over the fog. As the mix fell, it interacted with suspended water vapor, clearing the fog every time.

Today, working out of a civilian hangar, Blair can be found directing flights most mornings from October through February. Fog Ops has an agreement with Salt Lake City International through its largest operator, Delta Airlines, to banish the fog.

It’s not uncommon for Blair to get a 2 a.m. telephone call asking, “Can you stand by?” By 5 a.m. Blair and his crew—a pilot, a grinder, and a man with a bucket to fill the grinder’s hopper—are ready. As the warm upper atmosphere gains heat under the rising sun, the fog grows ever denser, and Blair’s team heads off to work. They load six insulated boxes of dry ice crystals into the company’s twin-engine Piper Chieftain and fly just above the fog, blanketing the runways.

“We’re usually flying up in the sunshine, just above the fog,” Blair says. “As the aircraft makes a turn you can see a little glint coming from down below as the first ice crystals begin to form. Then a hole opens up in the fog.” Occasionally, Blair says, the atmosphere will become so saturated with supercooled water molecules that the effort kicks off a four-hour snowstorm.

Despite unintended snow, the effort is a raging success. In the end the airlines pay Fog Ops less than $1 in fees for each plane that lands at Salt Lake City International. (They also pay a seasonal retainer.) With some 450 planes arriving daily, and potential losses of $50,000 to $900,000—depending on the particulars of the flight —for each plane that can’t get in or out, the value of fog abatement is staggering. Relatively small payments to Fog Ops provide carriers with the assurance that flights will run regularly and on time.

About 800 miles northeast of Salt Lake City, in the wide-open plains of western North Dakota, hail suppression is the goal. Hail forms inside powerful thunderstorms, often when warm, moist air rises rapidly in the atmosphere. In the Dakotas, these storms can have devastating effects on crops. For more than 30 years, the state of North Dakota has been seeding clouds with silver iodide both to abate the hail and to create rain. “We have eight aircraft standing ready,” says Darin Langerud, director of the North Dakota State Water Commission’s atmospheric research board, “and when conditions are right to promote rain or to suppress hail, they go up.”

“The hail suppression program is one of our great successes,” Langerud says. “We know this because we’ve worked with crop insurance companies for statistics. We compared virtually identical seeded and nonseeded areas of farmland, and the area where the seeding had been done showed a 45 percent lower incidence of hail-damage claims. We’re not saying that hail didn’t fall, but it fell in smaller pieces, which ultimately did less crop damage on the ground.”

It is one thing to increase rainfall or reduce the size of hailstones. But when it comes to controlling truly huge, complex, chaotic events like hurricanes and tornadoes, the fix remains theoretical. At least for now, the testing ground is a computer simulation or often just the space inside a physicist’s head.

“With powerful weather forces like hurricanes and tornadoes,” Ross Hoffman of AER says, “the biggest impediment to learning more about them and their structure is that you often can’t get good observations, since the conditions are just too extreme. In many cases the weather you’re hoping to measure renders your instruments unreliable near the event’s peak activity, just when you need them to measure best.” Still, those obstacles haven’t stopped Hoffman and others from hypothesizing how such systems might be modified and then simulating the fix on a computer screen.

Hurricanes, the largest and most damaging weather events, peak in late autumn, when winds coming off the coast of West Africa meet thunderstorms clustered over the warm tropical ocean. The resulting disturbance can form a self-sustaining low-pressure vortex, or what is called a tropical depression; as the system intensifies it becomes a tropical storm. Then, if the winds of this self-sustaining system top 75 miles an hour, it earns a new name: hurricane. In the end, the greater the difference between the temperature of the sea and that of the upper atmosphere, the more powerful the storm.

After studying this dynamic, Hoffman suggested a scheme to weaken a hurricane or shift its path by heating and cooling the atmosphere in complex patterns. While his plan would, theoretically, help tame the weather, we have no reliable way to heat or cool the atmosphere over large enough areas to move a massive storm. “So today,” Hoffman says, “while I can demonstrate that steering a hurricane is possible using computer simulations, we still don’t have a practical way to do it.”

Another hurricane-moderating hy­­poth­­esis, this one advanced by Daniel Rosenfeld of Hebrew University of Jerusalem and William Woodley, an independent weather-modification researcher based in Colorado, holds that seeding a hurricane’s lower reaches with microscopic dust particles—perhaps microbits of salt—would generate minute water droplets by giving the vapor something to attach to. The droplets would eventually be carried into the storm’s higher altitude, cooling the hurricane through evaporation in the same manner that sweat cools human skin. As the droplets evaporated, they would cool the air in the lower levels of the storm, diminishing its intensity. “Our simulations show that this would be the outcome,” Woodley says.

Even as enhanced computer modeling and more precise measurement bring control of extreme weather closer, those pushing the envelope find themselves facing the same hurdle as Bernard Vonnegut and his colleagues at General Electric half a century ago: the risk of getting sued.

“So here we are, back to weather modification’s critical issue,” says Michael Garstang, distinguished research professor emeritus of environmental sciences at the University of Virginia. “If you cannot predict very precisely what would have happened with, say, a hurricane before you began manipulating it, you’ve left yourself wide open to litigation. There’s just too big an opportunity for people to say: ‘You created this. You made it worse.’”

Charles Hosler agrees. “That’s exactly why there will never be large-scale weather modification or weather control in America. All weather is good for somebody and bad for somebody else.” When altered weather causes a problem for people, he contends, those people are likely to sue.

On this subject Hosler speaks from experience. Along with colleagues, he was once sued by a sightseer riding a ski lift. After the lift’s motor was hit and halted by lightning, the man jumped rather than wait for rescuers; on landing, he broke his leg. Then he discovered that Hosler and his team had been studying thunderclouds nearby. Soon all parties were involved in a lawsuit that was eventually tossed out of court.

Hosler recalls another colleague, this one working in hail abatement research in Pennsylvania, who ran afoul of local fruit farmers who worried that the effort might cause a drought and ruin their livelihood. They reacted by shooting bullets into the sky, hitting a plane flown by student pilots. “People, they get really emotional about their weather,” Hosler says.

If getting sued over a little lightning has some scientists in a tizzy, imagine the risk for those who seek to change the climate in a major way. Nevertheless, some mavericks feel we have no choice as we deal with global warming. Astrophysicist Gregory Benford of the University of California at Irvine, for instance, suggests dispersing tiny particles into the upper atmosphere to reflect sunlight away from us.

And then there’s Roger Angel, an astronomer and optical scientist at the University of Arizona who, working under a NASA grant, seeks to launch trillions of two-foot-wide disks of transparent film into orbit around Earth, a million miles up. The disks, each 250 nanometers thick and tended by “sheepdog” spacecraft to keep them in place, would shade us just enough to reduce sunlight by roughly 2 percent, cooling the planet back to preindustrial temperatures and perhaps moderating some of the destructive weather we have had in recent years.

“I estimate that the program would take 20 years and cost about $5 trillion,” Angel says. But what if, once shaded, Earth begins to overcool? Angel has a contingency there. “Over time, these disks will want to drift out of orbit. We could make it so they stayed in place for only so long.”

On the 8th of August, 91,000 people will be sitting in an open-air stadium in Beijing for the start of the 2008 Summer Olympics. With thousands of athletes in competition and millions of people watching the event on television, the last thing the Chinese government wants is a rainstorm to spoil this well-planned spectacle.

Tinkering with the weather is old hat for the Chinese, who have employed various cloud-busting techniques to trigger rainfall in their drought-plagued northern provinces, an area that includes Beijing, since the 1950s. For the Olympics, the world’s largest weather modification bureau will set up several banks of rocket launchers outside the city to blast threatening clouds with silver iodide and force them to release their rain before it reaches the Olympic stadium. The bureau has also been practicing a less well-honed strategy that involves overseeding the clouds to actually prevent rainfall; this technique increases the number of ice crystals in a cloud but decreases their mean size, which makes them less likely to fall as rain.

“None of these techniques is a proven technology,” says Roelof Bruintjes, an expert in weather modification at the National Center for Atmospheric Research in Colorado. “I am very skeptical of their having any chance of success.” Of course, the Chinese know full well that weather control is still more art than science. They are just hoping to beat the odds, which, according to historical records, call for a 50 percent chance of rain sometime during the events.

When the wrong weather hits the wrong region at the wrong time, the human and economic consequences can be devastating. Here is a list of the most costly events in recent times:

- Hurricane Mitch, an unusually slow-moving storm, ambled into Central America in 1998 and dumped almost six feet of rain, primarily on Honduras and Nicaragua. The combination of ferocious winds, heavy rainfall, flooding, and mud slides added up to more than 10,000 deaths, millions left homeless, and more than $5 billion in damage.

- The European heat wave of 2003 is estimated to have cost 35,000 to 50,000 lives, and its accompanying drought brought notable crop shortfalls. It is worth remembering, however, that drought in one part of a country is sometimes balanced by excess rain elsewhere.

Hurricane Katrina, which hit New Orleans and the Gulf Coast in 2005, is in a class by itself: In addition to the loss of life, it caused $40 billion in insurance losses. Thirty oil platforms and nine refineries were destroyed or forced to shut down, and tens of thousands of jobs were lost. Some estimates place the eventual total cost of the disaster at $200 billion.

- The Australian drought of 2006–2007 sliced about 1 percent off the country’s total economic output over the last few years, at the same time reducing wheat production and devastating farm incomes.

Carl Brenner

Original here

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