UNIVERSITY PARK, Pa. — While “nuclear winter” might sound hypothetical, its potential aftermath is no joke. If a large-scale nuclear war broke out, the resulting firestorms would spew massive amounts of soot into the atmosphere, blocking sunlight and plunging global temperatures. This sudden cooling could wipe out agriculture as we know it for more than a decade, bringing famine even to those who survive the blasts.
Researchers at Penn State decided to put numbers to the nightmare. Using simulation models, they studied how various nuclear war scenarios would impact corn production—the world’s most widely grown grain. Their conclusion? Depending on the scale of conflict, corn yields could drop by as much as 80%. They published their findings in Environmental Research Letters.
Let’s break it down: a smaller regional nuclear war, releasing about 5.5 million tons of soot, could reduce corn production worldwide by 7%. A full-scale global war—165 million tons of soot—could cause yields to crash by 80%. In total, the study explored six scenarios of increasing severity.
Lead researcher Yuning Shi explained why corn was chosen: it’s central to the global food system. An 80% drop would be catastrophic. Even a 7% decline would strain food systems, driving hunger and economic instability.
The simulations were powered by a model called Cycles, developed by Penn State’s College of Agricultural Sciences. It allows researchers to simulate crop growth over time across thousands of global locations, factoring in soil, plant, and atmospheric interactions.
“We simulated corn yields at nearly 38,600 locations under six different nuclear war scenarios,” Shi said. “This gives us a clearer picture of how vulnerable our food systems are to extreme global events.”
But there’s more. The team also factored in rising UV-B radiation—caused by ozone depletion following nuclear blasts. UV-B can damage plant DNA and reduce photosynthesis. They estimated that UV-B could add another 7% loss to corn yields, bringing the total decline to a worst-case 87%.
Here’s the science behind that: atomic explosions create nitrogen oxides in the stratosphere. Combined with heat-absorbing soot, these gases destroy ozone, which usually protects Earth from harmful UV rays.
The team offered one glimmer of hope: fast-growing, cold-resistant crops could soften the blow. Switching to these varieties might recover about 10% of yields. But there’s a catch—having the right seeds ready is key. That’s why the researchers recommend assembling “agricultural resilience kits” filled with seeds tailored to cold climates and short seasons.
“These kits could be crucial during the recovery phase post-war,” said Armen Kemanian, co-author and professor of production systems modeling. “They could also help after other major disasters like volcanic eruptions.”
Shi acknowledged that global preparation for such kits is unlikely, but spreading awareness might spark action. “If we want to survive the unimaginable, we need to prepare for it,” he said.
And this research isn’t only about nukes. Kemanian emphasized that similar devastation could come from natural catastrophes. “This isn’t just about war—it’s about understanding how fragile our biosphere really is.”
Contributors to the study included experts from Penn State, the National Center for Atmospheric Research, and the University of Southern California. Funding came from Open Philanthropy, DARPA, the USDA, NSF, and the Future of Life Institute.
At its core, this research is a wake-up call: the food systems we rely on are more vulnerable than we think—and preparation, even for the unthinkable, matters.
