This article originally appeared in Alternet.

California got a brief respite from its historic drought, thanks to a recent wave of storms that swept across the West Coast, filling reservoirs and replenishing snowpack. Grateful residents don’t just have El Niño to thank; part of the rainfall was, in fact, man-made. But there are some who believe something more sinister may be afoot.

Mother Nature gets a boost from science

Now suffering through its fifth year of a crippling drought, the Golden State was done waiting for Mother Nature to do her thing, so officials and scientists took matters into their own hands and revived an old cloud-seeding program to boost the region’s rainfall levels.

In January, the Los Angeles County Department of Public Works awarded a $500,000 one-year contract to North American Weather Consultants (NAWC), a Utah-based cloud-seeding company that performed similar work for the county in 1961, to help enhance the region’s rain production.

On the night of March 13, the firm switched on 10 cloud-seeding ground stations strategically positioned across the mountainous areas of northern Los Angeles between Sylmar and Pacoima in San Fernando Valley. The stations targeted cloud formations above Angeles National Forest, where rain would feed into tributaries supplying water to the Big Tujunga, Pacoima and San Gabriel dams. Thus began the first cloud-seeding project conducted by the DPW since 2002.

Ten cloud-seeding locations were selected across Los Angeles County. (image: Los Angeles County Department of Public Works)

Science fiction, minus the fiction

Like so much of modern science, the idea of controlling the weather started in the realm of fiction. But cloud seeding today “actually comes with a lot of science behind it,” said Kerjon Lee of the LA DPW in a recent interview with CBS News’ Carter Evans.

Discovered in 1946 by the American chemist and meteorologist Vincent Schaefer, a self-taught scientist who never completed high school, the principle of cloud seeding is actually quite simple. Particles of silver iodide — or sometimes potassium iodide, liquid propane or solid carbon dioxide in the form of dry ice — are sprayed into a saturated cloud to kickstart cloud condensation, a natural process in which particulate matter acts as nuclei that attract supercooled water vapor, which freezes into ice. Once those ice particles gain enough weight, they fall from their clouds, melt and turn into rain.

Cloud seeding can be done by ground generators, plane or rocket. (image: DooFi/Wikipedia)

Cloud seeding, chemtrails and conspiracy theories

While working as a researcher at General Electric, Schaefer modified clouds above Massachusetts’ Berkshire Mountains by seeding them with dry ice. But according to the U.S. National Research Council, “the potential legal liability implications of the early experiments led the General Electric Company to discontinue field experiments, and in 1947 to negotiate a contract for further fieldwork to be carried out by the military.” (Schaefer, who received 14 patents over a 20-year period, would continue to study weather modification, publishing a paper two years later about his experiments modifying lightning storms in the northern Rockies.)

Cloud-seeding’s shift from private research to national defense helped fuel conspiracy theories that zeroed in on aircraft contrails, those line-shaped clouds that sometimes form behind aircraft flying several miles above the Earth’s surface. A product of water vapor condensing and freezing around small particles present in an aircraft’s exhaust, these contrails, conspiracy theorists argue, are actually “chemtrails” that indicate the military or some other governmental organization is spraying chemical or biological agents at a high altitude for some mysterious, top-secret reason.

The theory galvanized with the release of a 1996 research paper by the U.S. Air Force about weather modification titled, “Weather as a Force Multiplier: Owning the Weather in 2025.” The report’s authors were quite clear about how weather manipulation might one day become weaponized:

The ability to modify the weather may be desirable both for economic and defense reasons. … Assuming that in 2025 our national security strategy includes weather-modification, its use in our national military strategy will naturally follow. Besides the significant benefits an operational capability would provide, another motivation to pursue weather-modification is to deter and counter potential adversaries. In this paper we show that appropriate application of weather-modification can provide battlespace dominance to a degree never before imagined. In the future, such operations will enhance air and space superiority and provide new options for battlespace shaping and battlespace awareness. “The technology is there, waiting for us to pull it all together; in 2025 we can “Own the Weather.”

“So persistent is the chemtrail theory that U.S. government agencies regularly receive calls from irate citizens demanding an explanation,” writes Oliver Smith, digital travel editor at the Telegraph. “Pernilla Hagberg, a Swedish politician, even raised the issue. … Other proponents of the ‘chemtrails’ theory say it is an attempt to control global warming, while some cite far more sinister goals, such as population control and military weapons testing.” In fact, contrails are believed to contribute to global warming by trapping radiation emitted by the Earth.

In 2014, Gawker’s weather blogger Dennis Mersereau offered his own debunking. He writes:

Chemtrail conspiracy theorists use cloud seeding as irrefutable proof that all of their theories are valid, because “look! they’re doing it here, so obviously they’re doing it everywhere and with other chemicals, too!” That’s a huge logical fallacy, but it’s their main fallback and argument, so they stick to it until the bitter end.

Contrails from a Qantas Boeing 747-400 at an altitude of 36,000 feet (image: Sergey Kustov/Wikipedia

Of course, these theories are regularly dismissed by the government, as well as aviation experts like pilot Patrick Smith, who writes in his book Cockpit Confidential: Everything You Need to Know About Air Travel:

Some have drawn the connection between contrail presence — though in this case they are “chemtrails” — and illness in certain communities. The vast online docket of photographs and eyewitness accounts does have a certain UFO-sightings tinge to it. If the idea sounds particularly cuckoo, I’ll mention that otherwise reasonable and skeptical people have taken to believing that something is going on, which is often a first sign that it is. That something, however, is probably no more villainous than standard military aircraft on maneuvers, albeit classified ones. If you live beneath one of these chemtrail-prone zones I’d recommend a good telephoto lens to identify what kinds of aircraft are involved. For the rest of us around major cities, all it takes is a decent pair of binoculars to realize the culprit is usually Lufthansa or Delta, and not some shadowy CIA spy plane.

The Los Angeles Department of Public Works actually helped stoke the conspiracy fire in late January, when it decided to notify local residents about the upcoming cloud-seeding equipment installations by taking out a classified ad in the Pasadena Star News. Conspiracy theorists saw the move as a way for the government to be legally transparent, yet virtually conceal the news of its activity.

On March 12, the conspiracy website Wakeup World published a blog post claiming the American government “quietly” admitted to engaging in “weather modification” activities in a notice buried in the classifieds section of a small California newspaper:

Weather modification, geoengineering, chemtrails; these are all topics that if brought up in most circles today, would garner the speaker the telltale look that most Truthers have become all too familiar with. It is a look that has been ingrained into all who have opted to cast aside their critical thinking for their comforting daily lie. There is a herd mentality that has been established that causes even those on the fence or those interested in “outside the box” ideas, to fall in line while surrounded by the docile mass. So when the government recently released a “Notice of Intent” on page 11 of the Pasadena Star Classifieds, announcing their plan to carry out weather modification in Los Angeles County, it became clear that those blank stares should be turned inward, for some much needed self-reflection and re-evaluation.

Writing on Snopes.com, Kim LaCapria points out that the DPW actually “devoted an entire page to the activity (cloud seeding) mentioned in the classified advertisement [PDF]. That document explained cloud seeding was an anti-drought measure practiced intermittently for more than half a century in Los Angeles.”

The future is now

Even in the scientific community, cloud seeding has long been relegated to fringe science, with the Australian Federation of Meteorology dismissing a handful of so-called “rain-making” weather modification experiments conducted throughout the early part of the 20th century. Even as recent as 2003, the United States National Research Council released a report stating that to date, there is still no convincing scientific proof of the efficacy of intentional weather modification as it only has 30 percent or less chance of success.

The report assessed the ability of current and proposed weather modification strategies meant to help with water resource management and weather hazard mitigation. The NRC noted the challenge of figuring out exactly how much rainfall would have happened if treated clouds had not been seeded:

[S]cience is unable to say with assurance which, if any, seeding techniques produce positive effects. In the 55 years following the first cloud-seeding demonstrations, substantial progress has been made in understanding the natural processes that account for our daily weather. Yet scientifically acceptable proof for significant seeding effects has not been achieved, and the scientific challenges have proved to be significantly more formidable and complex than perceived initially.

The 1996 Air Force report noted that it contained “fictional representations of future situations/scenarios.” With the increasing number of cloud-seeding programs happening around the world, it’s clear that the future is now. In Maharashtra, one of India’s largest and wealthiest states, a crippling drought now in its fourth year has crushed the region’s agriculture production and taken a severe human toll, with some 1,300 debt-burdened farmers committing suicide during a six-month period in 2014 alone.

One official response to the Indian crisis has been cloud seeding. The state’s revenue ministry hired Koliwad, a Bangalore-based climate modification consultancy, to carry out a three-month-long, $4.5 million cloud-seeding program covering a 100-square-mile area in what is the largest project of its kind ever attempted in the country. Koliwad, in turn, hired Weather Modification Inc., the world’s largest private aerial cloud-seeding company, based in Fargo, North Dakota, to develop a five-year technology transfer program that includes training Indian pilots, meteorologists and Doppler radar technicians how to seed clouds.

Some witnesses of the ensuing storms are under the impression that humans have finally figured out a way to control the weather. But Mother Nature still holds most of the cards. “People in Maharashtra are hoping for a cure-all to drought,” said Patrick Sweeney, WMI’s chief executive. “They come out and dance in the streets when it rains, they hug our pilots and say, ‘Do it again.’ But we can’t guarantee that the clouds will be there — and willing to cooperate.”

Cloud-seeding programs are not used only during severe drought situations. In France, cloud seeding has been used to reduce the damage to crops caused by hail. The strategy has been employed in Indonesia to help eliminate the pollution-heavy haze caused by the large swaths of open burning that are regularly started across the nation. And in the leadup to the 2008 Beijing Olympics, China launched an aggressive cloud-seeding program to reduce air pollution.

This image explaining cloud seeding shows either silver iodide or dry ice being dumped onto the cloud, which then becomes a rain shower. The process shown in the upper-right is what is happening inside the cloud and the process of condensation to the introduced chemicals. (image: Smcnab386/Wikipedia)

But just as some cloud-seeding programs have been rolled out to combat pollution, some worry about the potential health risks. Opponents point out that exposure to silver iodide can be harmful to mammals, which includes humans. But public health advocates have bigger things to worry about, as the silver iodide toxicity in the atmosphere represents about only 1 percent of industry emissions. “Cloud seeding is absolutely safe,” said Lee, assuring fellow Los Angeleños that the DPW’s plan poses no risk to public health.

A remotely operated cloud-seeding flare site in Santa Barbara County, Calif. (image: Los Angeles Department of Public Works)

Graeme Stevens, director of the Center for Climate Sciences at NASA’s Jet Propulsion Laboratory, is skeptical about California’s cloud-seeding plan, but not in the way conspiracy theorists are. “It is wishful thinking,” he told CBS News. “It’s been shown that under certain circumstances it works, but only in a very marginal way and even then, it would be difficult to prove.”

Los Angeles County officials disagree, contending that their plan will generate up to 15 percent more rainfall. “Based on our 50-year study,” said Lee, “we think we can get an additional 1.5 billion gallons a year.”

That matters to farmers like Mike DeWit, a second-generation rice farmer in California’s Sacramento Valley, who has been forced to oversee steep decreases in active acreage due to the drought and state-mandated water cutbacks. In 2013, DeWit farmed about 1,050 acres. Last year, he was down to between 350 and 380 acres.

But farmers can’t rely on hard-to-prove solutions like cloud seeding. If you work the soil, you must be prepared to handle both feast and famine, and the changing cycles of nature. It’s a principle DeWit fully understands. “We will get rain again,” he said. “And we will have another drought.”