Standing between beds of golden beets and elephant garlic in the garden of Lincoln Hills, a small organic farm in Placer County, California, Tammi Riedl looks up and points to a stripe of white haze running across a cloudless blue sky.

“See that?” she asks, raising her eyebrows. “What do you think that is?”

I look up. The white stripe looks like a normal contrail of jet engine exhaust to me. But to Tammi, a 54 year-old organic farmer, it’s a “chemtrail”: a toxic cocktail of aluminum, strontium and barium sprayed from planes in a plot to control the weather, the population and our food supply.

“See how it dissipates and becomes cloud cover?” she says. “That’s not normal.”

I nod, unsure how to respond to this unexpected declaration, and Tammi resumes demonstrating how to cover crop rows with frost blankets.

Tammi Reidl believes that to mitigate global warming, mysterious airplanes spray chemicals into the atmosphere to form sun-blocking artificial cloud cover. Photograph: Max Whittaker/The Guardian

For the month of January, in an attempt to escape seasonal and post-election depression, I applied to work as a part-time farmhand at Lincoln Hills in exchange for room and board after spotting the arrangement advertised on the website HelpX.

To someone accustomed to New York City’s mouse-infested apartments, the farm was cartoonishly idyllic: on 10 acres in the Sierra Nevada foothills, sheep graze on blackberry bushes, a baby mule frolics, and free-range chickens pluck worms from compost heaps. But for the residents who subscribe to the chemtrails conspiracy theory, what looks like a perfect bucolic scene feels shrouded in danger.

Tammi and her boyfriend, Rob Neuhauser, are among the estimated 5% of Americans who believe that various global powers, including the US government, run clandestine and harmful chemical-spraying programs.

Versions of the chemtrails (or “covert geoengineering”) theory abound, and Tammi’s goes roughly like this: to mitigate global warming, mysterious airplanes spray chemicals into the atmosphere to form sun-blocking artificial cloud cover. This is done in secret, because these chemicals wreak havoc on environmental and human health, causing “Alzheimer’s, all sorts of brain problems, cancer”, she says.

Despite her adherence to USDA organic guidelines, Tammi fears that the chemical spraying means the produce she sells and donates to the Placer Food Bank isn’t technically organic. “It makes me think, ‘Wow, are we going to have to start growing everything indoors, under tunnels?’” she says. “Because the air is not healthy for crops.”

A picture posted on Flickr by a user called chemtrailchaser. Photograph: Flickr

Scientists roundly reject the chemtrails theory, which started to gain followers in the mid-1990s. The trails you see behind airplanes, they explain, are harmless condensation trails, or contrails, formed when moist engine exhaust hits freezing temperatures at high altitudes.

Stoking the chemtrails theory is the fact that there are a few legitimate reasons for atmospheric spraying. Geoengineering scientists have indeed suggested fighting global warming by doing more or less what Tammi fears they’re already doing. So far, though, solar geoengineering remains in hypothetical or small-scale research stages.

To counter conspiracy theorists, in the early aughts the US Air Force featured a disclaimer on its website, stating that “the ‘chemtrail’ hoax has been investigated and refuted by many established and accredited universities, scientific organizations, and major media publications”. The EPA published a similar notice alongside a fact sheet about contrails. But this hasn’t been enough to sway true believers, who tend to dismiss skeptics as “sheeple” or shills.

Not your stereotypical conspiracists

Before I met Tammi, videos of far-right conspiracist radio host Alex Jones foaming at the mouth and claiming “they are spraying poisons on you” served as my prime example of what a believer in chemtrails might look like. I’d read articles that called such believers “idiots”, but I had never actually talked to one.

Tammi isn’t a caricature of a tinfoil hat-wearing conspiracist, and she’s not an idiot. Instead of crazy walls full of newspaper clippings, her house is decorated with dreamcatchers and her grandchildren’s drawings. After getting degrees in Applied Information Technology and Architectural Drafting from Capilano College in her hometown of Vancouver, she helped pioneer the “girl games” movement as a multimedia producer for game developer Purple Moon. In 2012, a biodynamic farming course at Rudolf Steiner College inspired her to quit her six-figure job as a financial controller and go back to the land.

Now, when she’s not laboring outside, she sells upcycled furniture, bakes pumpkin muffins and supplements her income with financial consulting services. She rarely discusses her beliefs unless prompted, though she occasionally reposts articles by so-called anti-vaxxers on Facebook.

She’s an example of how conspiracy theories, once a fringe obsession, have gone mainstream – and how “alternative facts” aren’t just for the right wing.

Before I left Lincoln Hills, Tammi and Rob let me interview them about their beliefs. I wanted to know how these socially progressive, educated and entrepreneurial organic farmers came to reject the authority of science – and what it would take to redirect their concerns toward real and dire environmental threats.

At the heart of it: Facebook

Facebook made a believer out of Tammi. When she moved to Lincoln in 2012, she’d never heard of chemtrails. Three years later, around the time her mare gave birth to twin mules, a post about a Facebook group called Sierra Nevada Geoengineering Awareness popped up in her newsfeed. Thinking it was related to agriculture, she joined the group.

The group’s 500 members post constantly about “aerosol attacks”, “toxic silver skies”, “mad men playing god with our weather, blocking our life-giving sun”.

The movement’s mantra is “LOOK UP”. Tammi obeyed. “I started looking up at the sky, noticing it was just crisscrossed.” When she told Rob about her discovery, he was convinced.

Tammi became “obsessed”. “I was taking pictures, videotaping the sky,” she says. “And I was like, I wish I didn’t know, because now that I know, it’s really making my heart sad.”

In early January, Tammi felt cautiously optimistic about how the Trump administration would affect organic farmers. Born in Canada, Tammi isn’t a US citizen, but given the option to vote – despite thinking Trump is “a prick” – she “probably would’ve picked him”. Given her environmentalism and hippie-dippy aesthetic, this shocked me.

The fake news website quoting Donald Trump as saying he would ‘end chemtrailing’. Photograph: Screengrab

While teaching me how to candy grapefruit peels, Tammi explained her optimism: Todd, her dairy farmer neighbor, claimed that “Trump promised to end chemtrails”.

Curious where Todd might’ve found this information, I Googled “Trump chemtrails”. It turned up a dubious news report from 16 January, which featured what looked like a screenshot of a tweet by Donald Trump: “My very first executive order will END the chemtrailing across America. #MAGA,” it read.

At first I couldn’t tell if the site was satirical, or whether the tweet was really authored by Trump – it wouldn’t have been the most outrageous missive from the man who once supported the “birther” theory.

Another Google search clarified that the tweet was impersonated. But if I’d encountered it as a middle-aged farmer worried about toxic clouds and untrained in spotting fake news, I probably would’ve told my friends that the president-elect had promised to end chemtrailing.

In a textbook case of confirmation bias, from 20-25 January, some members of Sierra Nevada Geoengineering Awareness claimed the skies were clearer than they’d been in months. Tammi read aloud a post dated 23 January: “Beautiful Blue Skies!!! I haven’t seen any Spraying Activity since Trump took office … Anyone else out there think that the ‘tide has turned?’”

Sabrina Lamont, a Lincoln Hills farmhand with a buzzcut and tattoos of her dogs’ names, says she became a conspiracist while working as a National Guard truck mechanic in Pennsylvania.

“To me, chemtrails aren’t that farfetched,” she says. To put her beliefs into context, she cites known examples of the military conducting secret human experiments – such as the time in 1950 when the army sprayed bacteria into San Francisco’s fog in a “simulated germ-warfare attack”, leaving one man dead.

Despite the protests of her wife, an ICU nurse with a “Love Trumps Hate” bumper sticker, Sabrina voted for Trump. “He’s not a stellar guy,” Sabrina says, “but I think he’s what America needs to wake up.”

A group plagued with infighting

Trump, ironically, may actually be on track to initiate the world’s first large-scale atmospheric spraying program – the type of planet-hacking that Tammi fears is already under way. In January, for the first time ever, a White House report submitted to Congress called for research into geoengineering. In March, climate scholars gathered in Washington to discuss cooling the planet by shooting aerosols into the stratosphere, among other potentially risky approaches.

Tammi Riedl checks on oranges on her farm. Photograph: Max Whittaker/The Guardian

“Worryingly, geoengineering may emerge as this administration’s preferred approach to global warming,” Silvia Riberio, with technology watchdog ETC Group, told the Guardian in March. “In their view, building a big beautiful wall of sulphate in the sky could be a perfect excuse to allow uncontrolled fossil fuel extraction.”

In the months leading up to Trump’s election, Sierra Nevada Geoengineering Awareness was plagued with infighting. A faction of climate change deniers, feeling vindicated by Trump’s anti-establishment message, sparred with members who believe in human-accelerated climate change and thought a Trump presidency spelled doom.

“People are so divided, even within this movement,” says Lisa Thomas, creator and moderator of Sierra Nevada Geoengineering Awareness. “It’s difficult to find enough common ground to make progress.” In October, she called off the group’s monthly meetings.

A homeschooling mother of two, Lisa exemplifies how concern about geoengineering can become all-consuming. She’s spent the past four years spreading “geoengineering awareness” with missionary zeal.

One afternoon in 2014, for example, following what she calls “heavy spraying” which she says left a metallic sheen on the surfaces of her ponds and depleted the honeybee population around her Spanish lavender, Lisa drove into town and marched around holding a sign that said “LOOK UP”.

“See how the sky is a steely color?” Lisa says when I meet her at her home in Penn Valley. The sky is a normal-looking blue, cloudless and trail-less, but she insists this is “rare” and that “it used to be more turquoise”.

A screengrab of a picture found on the Sierra Nevada Geoengineering Awareness website.

When she moved to California from Vermont 11 years ago, Lisa had a “Pollyanna streak”. “I used to salute the flag and get a tear in my eye,” she says. “I just didn’t know that the government would do the kind of stuff they do.”

When Lisa first heard about chemtrails, through neighbors and social media, she was skeptical. That changed on 14 April 2013, the exact date she says she noticed planes flying over her house, “whiting out the sky”. Afterward she claims her health began to deteriorate: “My hair started falling out, my asthma was terrible, I had sinus issues and headaches.” Her gardens, she says, also suffered: “There was a complete insect die-off. Anthracnose fungus on the oak trees. I found a frog with a missing leg and an elongated tailbone. I stayed inside for all of 2013. I didn’t go outside without wearing a mask.”

She believes these symptoms were caused by military aircraft from the nearby Beale Air Force Base conducting geoengineering experiments throughout Nevada County.

Now, Lisa says, “you’d never, ever convince” her that the trails in the skies are harmless.

In her garage lies a cardboard box filled with Ziploc bags, labeled “DO NOT THROW OUT”. It contains leaves Lisa claims are coated in “metallic flecks”. I ask if she’d ever gotten these leaves tested. She hasn’t, because “testing objects is expensive”, but she’s done seven water tests on her ponds, and says they turned up abnormal levels of aluminum, barium and strontium.

“My family and friends completely believe me,” Lisa says. The last awareness-raising event she held drew around 70 people. “They were all concerned. I don’t think there was a skeptical person in the audience. I happen to not care whether anyone thinks I’m half-crazy. I’ve done enough research.”

‘I’d like to see things you’ve read’

Tammi fears that chemical spraying via ‘chemtrails’ means the produce she sells and donate isn’t technically organic. Photograph: Max Whittaker/The Guardian

One morning, when Tammi suggests the clouds look suspicious, I mention articles I’d read that convinced me, as a former fact-checker, that “covert geoengineering” is an unfounded conspiracy theory.

“God, I’d love to find out it’s just a bunch of freakin’ people with too much time on their hands,” Tammi says. “I’d like to see things you’ve read.”



Over beers, I show Tammi and Rob the first ever peer-reviewed study testing the chemtrails theory, conducted by researchers at the Carnegie Institution for Science in 2016. When asked if they’d ever uncovered possible evidence of a government chemtrail program in their research, 76 out of 77 leading atmospheric scientists and geochemists said no.

When assessing photos of contrails, 100% of the experts indicated that the simplest explanation of the trails pictured was not a secret, large-scale atmospheric spraying program. One photo pictured a contrail broken by a gap, which some chemtrail believers argue reflects that chemical spraying was turned off, then on again. But experts explain that such gaps are caused by changes in air temperature or humidity – the same basic phenomenon behind why you can see your breath when it’s cold out, but not when it’s warm.

I play Tammi and Rob a YouTube video by Mick West, who runs the conspiracy theory-debunking blog Metabunk. Going through 70 years of books on the science of clouds, West explains why, depending on atmospheric conditions, contrails can either evaporate rapidly or persist and grow into sheets of cirrostratus.

After this show-and-tell session, Rob claims “nothing will change [his] mind”, but Tammi says the video in particular put her “on the fence”.

And when I show her the impersonated Trump tweet that promised to “end the chemtrailing”, she declares herself “media illiterate”.

“How does someone like me know what’s true and what’s not?” she says. “I’m 54 years old. I don’t watch the news. I don’t listen to the news on the radio. Then when I’m on the internet, and I see something where I’m like, ‘Holy shit, really?,’ I’m led down this path of believing it. I don’t have the knowledge that a journalist has about how verifiable is the source. When you’re just a standard person, you can really be led to believe anything. Because of the internet, anybody can put news out there. How do I know if it’s the truth or not? It makes it hard when you’re trying to choose a president. People chose Donald Trump because [they thought] he tweeted he was gonna stop chemtrails – you know what I mean?”

Perhaps the great tragedy of geoengineering hysteria is all the misdirected activist energy. Aircraft emissions do, in fact, pose an environmental risk: they contribute significantly to global warming. But instead of holding airlines and policymakers accountable for cutting emissions, anti-geoengineering activists shake their fists at the sky and curse a vague, unknowable “they”.

When I ask Lisa how concern about geoengineering affects her emotionally, she tears up. “Well, I want a future for my kids,” she says. “I worry about it all the time.” Only 5% of Americans believe in chemtrails, but plenty more share a similar, deep-seated dread about the planet’s future. To top it off, our current realities often feel darker and stranger than a conspiracist’s wildest fantasies.



Further south in California’s central valley, for example, the toxic insecticide chlorpyrifos is wafting from citrus groves onto children’s playgrounds, thanks to Trump’s decision to reverse the EPA’s ban on the chemical. Against a grim backdrop of assaults on the environment, from the approval of the Dakota Access pipeline to the gutting of Barack Obama’s clean power plan, it’s not paranoid to think that people in power engage in practices that pollute our air and water. Nor has it ever been crazy to suggest that politicians and corporations can lie.

Working on the farm, I started to see white hazy streaks in the sky as allegorical shorthand for a host of 21st-century anxieties – about corruption, illness, and looming climate catastrophe and environmental toxins. As Sabrina put it: “In my opinion, there’s no such thing as fully organic anything anymore.”

At Lincoln Hills, that may be the case. Tammi has legitimate reason to fear her crops are exposed to harmful chemicals. The Nevada Irrigation District (NID) sprays the herbicide glyphosate into the canal that runs across her farm. Though she has a “no spray” agreement with the NID – prohibiting them from spraying within her property lines, as long as she’s responsible for the grueling task of canal-weeding – they still spray upstream, just feet above her land.

‘My gut tells me something’s going on’

In April, I return to Lincoln Hills and ask Tammi and Rob if their beliefs have changed since February. We eat sliced apples as Tammi’s three-year-old grandson runs around in cowboy boots and her nine-year-old grandson picks chamomile for tea.

Tammi: ‘I never saw clouds like that as a kid.’ Photograph: Max Whittaker/The Guardian

Rob says that after being presented with factual evidence against chemtrails, he’s now more convinced in his beliefs – an example of a phenomenon called the backfire effect.

Tammi, though, says the facts got her “questioning”. “If I wasn’t so busy farming, I’d do more research,” she says. “I need more information. But then when I see it, heavy in the sky, I think, there’s no fucking way that’s not chemtrails. I never saw clouds like that as a kid. My gut and heart still tell me something’s going on.”

The news Tammi has read since January has left her disillusioned. After being cautiously optimistic about Trump, she’s now “really disappointed”, especially by the proposal of the EPA’s termination.

“I get the sense that there were a lot of outright lies,” she says. “And now we’re screwed.”

Even for the most rationally minded among us, “gut and heart” can hold more sway than dry presentations of facts. When asked for evidence supporting their convictions, chemtrails believers kept returning to what they themselves had seen.



Primary experiences, they suggest, are a more trustworthy gauge of truth than scientific consensus or the mainstream news. Even if their interpretations of these experiences were dictated by strangers on the internet, at least those strangers don’t call them crazy.

“This is something I truly believe: the news only broadcasts what they want the public to know,” Rob says. “They’re not gonna broadcast the full truth about anything, ever.”

Roughly 68% of Americans share this distrust in mass media. Instead of the news, Rob says he gets his information from friends he respects.

If Rob were to start reading the news, he’d discover that most mainstream reporting about conspiracists ranges from subtly to explicitly condescending in tone. Maybe this seemed all in good fun back when conspiracy theories appeared to hold no sway in national politics. But with our new conspiracy-theorist-in-chief, President Trump, it’s become counterproductive to laugh off the fact-averse as paranoid kooks, or to passively ignore their perspectives in hopes that science will inevitably prevail.

Research suggests that condescension and passive dismissal won’t help change minds – especially given that conspiracy theorists are more likely to meet the criteria for all types of psychological disorder, including anxiety, depression and being socially disadvantaged.

When I explain the focus of this article to Tammi, she expects condescension. “Oh, great,” she says, “it’s gonna be like, ‘Look at those farmers out there, concerned about weird shit – UFOs!’”

Of course, condescension from mainstream institutions only strengthens the impulse to find a sense of power in theories that reject mainstream thinking.

Tammi walks her land under a clear sky. Photograph: Max Whittaker/The Guardian

While driving me to a scenic overlook where she photographed the sky every few days for a year, Lisa plays a folk song she wrote about geoengineering. It’s called Veil Makers.



“The guitarist smoked a little too much dope while recording,” she says. But Lisa has a beautiful clear voice and I’m startled to find it gives me goosebumps.

“Tell me about the sky,” she sings. “Do you remember when it was blue?”

Lisa nods toward an elderly woman sitting on the porch of a white Victorian: “She ended up in the emergency room with a lung infection after a big fat spray turned the trees yellow.”

At the overlook, mist hangs in the Ponderosa pines. Across the valley is the faint ridge of the Sutter Buttes. “Those mountains used to be clearly visible,” Lisa says. The song continues: “Don’t people wonder why the sky is white?”

It strikes me that our relationship to facts has become so tenuous that we can literally no longer agree on whether the sky is blue.

When she hugs me goodbye, Lisa says: “Be careful. Watch your back. It’s a dangerous topic.”

I tell her I will be careful, then drive south, not a plane or a cloud in sight.