Modern-day farming is a high-tech operation highly dependent on GPS-guided tractors revolutionizing the way crops are planted, fertilized and harvested. But on May 10, 2024, that system came under attack, not from mechanical failure or sophisticated hackers, but from the sun itself.
On that day, the sun unleashed its largest geomagnetic storm in decades. The rare G5-class event sent shockwaves through Earth's ionosphere, disrupting GPS systems nationwide.
While the G5 storm wowed observers around the world with some of the strongest auroras in 500 years, the storm was nothing short of a nightmare for farmers in the American Midwest. "Our tractors acted like they were demon possessed," aurora chaser Elaine Ramstad, told Spaceweather.com.
Modern farming relies heavily on precision. Using GPS-guided tractors, farmers can plant thousands of acres in perfectly straight rows, accurately applying just the right amount of fertilizer to ensure optimum yields. When it's time to harvest, the machines can return to the exact same positions to pick the crops, minimizing wastage and ensuring maximum efficiency.
However, this technology-dependent agriculture is highly vulnerable to strong solar storms.
"If it just happens at the wrong time, in the wrong season, if it holds everything up by three or four days. It can have a significant impact on agriculture," solar and astrophysical researcher Scott McIntosh told Space.com.
Scott explains that if the same powerful storms hit 20 years ago, it wouldn't have really mattered to farmers as they weren't dependent on GPS. But now, our increased reliance on automation means solar storms can be a nightmare for farmers.
"I would guess 80% or more of all farmers in the Midwest use at least basic GPS for something — whether it's auto-steer or yield mapping," Ethan Smidt, a service manager for agricultural machinery manufacturer John Deere, told Spaceweather.com. "At least 50% of all farmers are VERY reliant on GPS and use it on every machine all year long."
The May 10 solar storm exposed a critical vulnerability in this high-tech, highly-precise, system. Geomagnetic storms, also known as solar storms, are disturbances to Earth's magnetic field caused by large expulsions of plasma and magnetic fields from the sun's atmosphere in the form of coronal mass ejections (CMEs).
During a powerful solar storm, like the one experienced in May 2024, Earth's ionosphere — the layer responsible for transmitting GPS signals from satellites to Earth — becomes disrupted. The layer becomes turbulent, distorting radio signals from GPS satellites, causing tractors and harvesters to lose their connections — or worse, veer off course.
"Our tractors acted like they were demon possessed," Ramstad recalls. "All my cousins called me during the storm to say 'my auroras' were driving them crazy while they were planting." Tractors, unable to maintain GPS locks, lurched back and forth, forcing farmers to switch to manual controls or stop entirely.
And it wasn't an isolated event. Smaller solar storms in October, classified as G3 and G4 events, caused similar issues during the harvest season.
Ramstad experienced the effect of a strong solar storm again on Oct. 6 when her tractor started acting up. "As the aurora activity began, my GPS was off by close to a foot. Twice while on Autosteer, the tractor danced a row to the left, to the right — and then the defoliator was off a row, so I had to loop around and start over. By nightfall, there was no controlling the Autosteer." Ramstad reported.
Randstad wasn't the only one to experience problems during the October solar storms.
"This fall was the first time I got to see the aurora, and my hair was standing on end from the beauty," Indiana farmer Michael Spencer told Spaceweather.com. "When the storms were strongest around Oct. 7th, my tractor's Autosteer system would 'jump the line' —meaning, the tractor would make a quick jolt left or right and I would have to manually reset."
Farmers can expect more frequent disruptions as solar activity conditions remain high during solar maximum — a period of heightened activity during the sun's approximately 11-year solar cycle.
While extreme G5 storms like the one on May 10, 2024, are rare, even moderate G3 and G4 events can cause significant problems. For farmers, this means planning fieldwork around solar activity and being prepared for unexpected delays. The economic implications are serious. Delays in planting or harvesting can lead to lower yields while recalibrating or repairing GPS systems adds financial strain during already tight seasons.
"The next generation of autonomy is being developed to use machine vision, artificial intelligence, and expert systems for guidance to avoid vulnerability to GPS outages." Terry Griffin, a Kansas State University professor reported in farmdoc Daily.
