Thursday, July 24, 2025

Simulating the unthinkable: Models show nuclear winter food production plunge

Researchers use Penn State’s Cycles agroecosystem model to predict how nuclear war ramifications would impact crops; recommend preparing ‘agricultural resilience kits’

Peer-Reviewed Publication

Penn State

corn crops in nuclear winter — image:
This comparison global map illustration shows one potential scenario outcome and how corn crops would be negatively affected by cold temperatures and shorter growing seasons resulting from soot injections into the atmosphere from nuclear explosions. On top: In mid-latitude regions of the Northern Hemisphere, planting is limited by temperature, with dates typically falling between April and May. In tropical and southern mid-latitude regions, planting is more variable due to precipitation-limited regimes, with spatial patterns reflecting the timing of rainy seasons. On the bottom: Corn types that would take longer to mature can grow in the tropics, while those that take less time to mature do better in the Northern Hemisphere.
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Credit: Penn State

UNIVERSITY PARK, Pa. — A nuclear winter is a theoretical concept, but if the climate scenario expected to follow a large-scale nuclear war, in which smoke and soot from firestorms block sunlight, came to fruition, global temperatures would sharply drop, extinguishing most agriculture. A nuclear winter could last for more than a decade, potentially leading to widespread famine for those who survive the devastation of the bomb blasts. Now, a team led by researchers at Penn State have modeled precisely how various nuclear winter scenarios could impact global production of corn — the most widely planted grain crop in the world. They also recommended preparing “agricultural resilience kits” with seeds for faster-growing varieties better adapted to colder temperatures that could potentially help offset the impact of nuclear winter, as well as natural disasters like volcanic eruptions.

In findings recently published in Environmental Research Letters, the team reported that the level of corn crop decline would vary, depending on the scale of the conflict. A regional nuclear war, which would send about 5.5 tons of soot into the atmosphere, could reduce world-wide annual corn production by 7%. A large-scale global war, injecting 165 tons of soot into the atmosphere, could lead to an 80% drop in annual corn yields. In all, the study simulated six nuclear war scenarios with varying soot injections.

Because of the crop’s global significance, the researchers chose to model corn’s collapse in a nuclear winter to represent the expected fate of agriculture overall, according to study first author Yuning Shi, associate research professor in Penn State’s Department of Plant Science. He noted that an 80% drop in global crop production would have catastrophic consequences, leading to a widespread global food crisis. Even a 7% drop in global crop production would have a severe impact on the global food system and economy, likely resulting in increased food insecurity and hunger.

The simulations were possible thanks to the Cycles agroecosystem model, created a few years ago by scientists in Penn State’s College of Agricultural Sciences, including lead developer Armen Kemanian, professor of production systems and modeling and corresponding author on this study. Using high-performance computing and considering atmospheric conditions, Cycles enables large-scale, high-resolution, multi-year simulations of crop growth by meticulously tracking the carbon and nitrogen cycles within the soil-plant-atmosphere system.

“We simulated corn production in 38,572 locations under the six nuclear war scenarios of increasing severity — with soot injections ranging from 5 to 165 tons,” Shi said. “This investigation advances our understanding of global agricultural resilience and adaptation in response to catastrophic climatic disruptions.”

In addition to considering the effects of massive amounts of soot in the atmosphere, the researchers modeled the increase in UV-B radiation — a type of ultraviolet radiation that can lead to DNA damage, oxidative stress and reduced photosynthesis in plants — that would reach Earth’s surface in a nuclear winter that could further limit agriculture.

Shi said he believes that this was the first study to estimate the extent of UV-B radiation damage to agriculture after nuclear explosions, which the researchers predicted would peak six to eight years after a global war. They estimated this could further cut corn production by an additional 7%, for a total worst-case scenario of an 87% drop in corn production.

Ozone high in Earth’s atmosphere effectively absorbs the bulk of UV radiation the planet receives from the sun, but nuclear war would dismantle this ability, Shi explained.

“The blast and fireball of atomic explosions produce nitrogen oxides in the stratosphere,” he said. “The presence of both nitrogen oxides and heating from absorptive soot could rapidly destroy ozone, increasing UV-B radiation levels at the Earth’s surface. This would damage plant tissue and further limit global food production.”

While the predictions point to potentially catastrophic drops in the production of corn varieties currently grown, Shi said, switching to crop varieties that can grow under cooler conditions in shorter growing seasons could boost global crop production by 10% compared to no adaptation. However, seed availability for these crops could become a serious problem — a "bottleneck to adaptation,” the researchers said.

Their proposed solution is to prepare “agricultural resilience kits” ahead of any nuclear disaster, containing region- and climate-specific seeds for crop varieties that can grow under cooler conditions with shorter growing seasons to survive lower temperatures.

“These kits would help sustain food production during the unstable years following a nuclear war, while supply chains and infrastructure recover,” Kemanian said. “The agricultural resilience kits concept can be expanded to other disasters — when catastrophes of these magnitude strike, resilience is of the essence.”

Shi noted that while proactive, internationally coordinated planning for such kits is unlikely, simply increasing awareness could help lead to better preparedness. “If we want to survive, we must be prepared, even for unthinkable consequences,” he said.

Kemanian said he sees value in the research beyond human-caused calamity.

“Recall that catastrophes of this nature can happen not just because of nuclear war, but due to, for example, violent volcanic eruptions,” he said. “One may think that studies of this nature are just navel gazing, but they force us to realize the fragility of the biosphere — the totality of all living things and how they interact with one another and the environment.”

Contributing to the research at Penn State were Felipe Montes, associate research professor of cropping systems modeling; Francesco Di Gioia, associate professor of vegetable crop science; and Charles Anderson, professor of biology and principal investigator of the project funding this work; as well as Charles Bardeen, with the Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, Colorado; and Yolanda Gil, Deborah Khider and Varun Ratnakar, all with the Information Sciences Institute, University of Southern California.

This research was supported by Open Philanthropy, the Defense Advanced Research Projects Agency, the U.S. Department of Agriculture National Institute of Food and Agriculture, the U.S. National Science Foundation and the Future of Life Institute.

At Penn State, researchers are solving real problems that impact the health, safety and quality of life of people across the commonwealth, the nation and around the world.  

For decades, federal support for research has fueled innovation that makes our country safer, our industries more competitive and our economy stronger. Recent federal funding cuts threaten this progress.  

Learn more about the implications of federal funding cuts to our future at Research or Regress.

Journal

Environmental Research Letters

DOI

10.1088/1748-9326/adcfb5

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Adapting agriculture to climate catastrophes: the nuclear winter case

When dreams turn dark: Neuroscientists to study nightmares and mental health

Penn State

Researchers lead project to gain insight into the purpose of dreams — image:
Nanyin Zhang, the Dorothy Foehr Huck and J. Lloyd Chair in Brain Imaging and professor of biomedical engineering, of electrical engineering and of engineering science and mechanics; Patrick Drew, professor of engineering science and mechanics, of biomedical engineering, of neurosurgery and of biology; and Nikki Crowley, associate professor of biology and of biomedical engineering, Huck Early Career Chair in Neurobiology and Neural Engineering and director of the Penn State Neuroscience Institute at University Park, received a three-year, $1.2 million grant from the W.M. Keck Foundation to gain insight into the purpose of dreams.
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Credit: Keith Hickey/Penn State

UNIVERSITY PARK, Pa. — Dreams, and likely nightmares, are experienced universally across humans and animals, but neuroscientists still do not know why. Now, with a three-year, $1.2 million grant from the W.M. Keck Foundation, an interdisciplinary team of researchers at Penn State will study the underlying mechanisms of nightmares and their relationship with anxiety-related mental health disorders, such as post-traumatic stress disorder (PTSD).

The team aiming to expand the scientific understanding of nightmares includes principal investigator Patrick Drew, professor of engineering science and mechanics at Penn State; and co-principal investigators Nikki Crowley, associate professor of biology and of biomedical engineering, Huck Early Career Chair in Neurobiology and Neural Engineering and director of the Penn State Neuroscience Institute at University Park; and Nanyin Zhang, the Dorothy Foehr Huck and J. Lloyd Chair in Brain Imaging and professor of biomedical engineering, of electrical engineering and of engineering science and mechanics.

“To me, the exciting thing about this research is that we now have a way to gain insight into the purpose of dreams,” said Drew, who also has affiliations with the biomedical engineering, neurosurgery and biology departments at Penn State. “The question of why we dream has puzzled mankind for millennia, and by looking at what changes in neural circuits and behaviors nightmares cause, we hope to be able to figure out the biological purpose of dreaming.”

To investigate the neural mechanics of nightmares, the researchers will rely on the side effects of the drug mefloquine, which was once used by American soldiers as a disease preventative during deployments to Somalia, Afghanistan and Iraq. Though effective in preventing malaria, the drug is no longer prescribed due its serious neurological side effects, including inducing nightmares. The researchers will test mice treated with the drug for two weeks while monitoring them for unusual behaviors.

“In the past, it has been hard to study dreams, because it is hard to determine what is a regular dream state and what is a nightmare,” Zhang said.

Led by Drew, researchers will use novel imaging techniques to map the mice’s facial expressions and pupil sizes to know which sleep stage they are in. The team will also use functional magnetic resonance imaging (fMRI), led by Zhang, and calcium signal recording, led by Drew, to record the specific neuron type that might be underlying the dream or nightmare.

Through the various imaging methods and behavioral observations, researchers will record what is happening within the animals’ brains at each sleep stage, including rapid eye movement and non-rapid eye movement stages. The researchers, led by Crowley, will also monitor the neurotransmitters and neuromodulators in two regions of the brain, the prefrontal cortex and amygdala, to understand how these systems are disrupted during nightmares. Through these observations, the researchers said they hope to determine if there is an indication of nightmares having a relationship with mental health disorders, like PTSD.

“Most people believe that nightmares are a consequence of having PTSD, but there is also the possibility that nightmares could exacerbate symptoms or even cause the presence of mental disorders,” Zhang explained.

Using the mice as a model, the researchers said they plan to develop a framework to predict the onset of mental health disorders, such as anxiety, due to the presence or absence of nightmares. If successful, their model could lead to sleep intervention-based treatments for people suffering with these conditions, according to the researchers.

“Penn State is distinctively suited to carry out this research, both in the capabilities of our team and in possessing the resources and intellectual space for a high-risk question like this one,” Crowley said. “Our post-docs and grad students, in particular, have an opportunity to contribute to a fascinating philosophical and biological research question that very few scientists will ever get to work on in their entire career.”

The W. M. Keck Foundation was established in 1954 by oil company founder William Myron Keck. As a philanthropic institution, the foundation supports discoveries in science, engineering and medical research that are distinctive or novel in their approach or promise to develop new technologies, instrumentation or methods. This award is the first W. M. Keck Foundation grant directed to Penn State in almost 25 years.

New research supports Ivermectin as an effective strategy to control malaria transmission

The BOHEMIA trial in Kenya showed a 26% reduction in new malaria infections among children aged 5-15

Barcelona Institute for Global Health (ISGlobal)

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Ivermectin tablets used for the BOHEMIA trial in Kenya
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Credit: Life Spark Studios/BOHEMIA project

Ivermectin administered to the whole population significantly reduces malaria transmission, offering new hope in the fight against the disease. The BOHEMIA trial, the largest study on ivermectin for malaria to date, showed a 26% reduction in new malaria infection on top of existing bed nets, providing strong evidence of ivermectin’s potential as a complementary tool in malaria control. The results of this project, coordinated by the Barcelona Institute for Global Health (ISGlobal) -an institution supported by the “la Caixa” Foundation- in collaboration with the Manhiça Health Research Centre (CISM) and the KEMRI-Wellcome Trust Research Programme, have been published in The New England Journal of Medicine.

Malaria remains a global health challenge, with 263 million cases and 597,000 deaths reported in 2023. Current vector control methods, such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), have become less effective due to insecticide resistance and behavioural adaptations in mosquitoes to bite outdoors and during dusk or dawn, when people are not protected by these measures. This underscores the urgent need for innovative solutions to combat malaria.

Ivermectin for malaria: A novel strategy

Ivermectin, a drug traditionally used to treat neglected tropical diseases like onchocerciasis, which causes river blindness, and lymphatic filariasis, which causes elephantiasis, has been shown to reduce malaria transmission by killing the mosquitoes that feed on treated individuals. Given the rising resistance to conventional insecticides, ivermectin could offer an effective new approach to tackle malaria transmission, especially in regions where traditional methods have become less effective.

The Unitaid-funded BOHEMIA project (Broad One Health Endectocide-based Malaria Intervention in Africa) conducted two Mass Drug Administration (MDA) trials in the high-burden malaria regions: Kwale County (Kenya) and Mopeia district (Mozambique). The trials assessed the safety and efficacy of a single monthly dose of ivermectin (400 mcg/kg) given for three consecutive months at the start of the rainy season in reducing malaria transmission. In Kenya, the intervention targeted children aged 5–15, while in Mozambique it focused on children under five.

Malaria reduction in Kenya

In Kwale County, Kenya, children who received ivermectin experienced a 26% reduction in malaria infection incidence compared to those who received albendazole, the control drug used in the study. The trial involved over 20,000 participants and more than 56,000 treatments, demonstrating that ivermectin significantly reduced malaria infection rates—particularly among children living further from cluster borders or in areas where drug distribution was more efficient. Moreover, the safety profile of ivermectin was favourable, with no severe drug-related adverse events and only mild, transient side effects already seen with ivermectin in campaigns against neglected tropical diseases.

“We are thrilled with these results”, says Carlos Chaccour, co-principal investigator of the BOHEMIA project and ISGlobal researcher at the time of the study. “Ivermectin has shown great promise in reducing malaria transmission and could complement existing control measures. With continued research, ivermectin MDA could become an effective tool for malaria control and even contribute to elimination efforts,” Chaccour, who is now a researcher at the Navarra Centre for International Development at the University of Navarra, adds.

“These results align with the World Health Organization’s (WHO) criteria for new vector control tools”, states Joseph Mwangangi, from the KEMRI-Wellcome Trust Research Programme. “The findings suggest that ivermectin MDA could be a valuable complementary strategy for malaria control, particularly in areas where mosquito resistance to insecticides is a growing concern”, adds Marta Maia, BOHEMIA’s lead entomologist from the University of Oxford.

Lessons from the Mozambique trial

In contrast, the implementation of the Mozambique trial in the rural district of Mopeia faced severe disruptions due to Cyclone Gombe (2022) and a subsequent cholera outbreak, which significantly disrupted operations. “One of the most important lessons we learned from the trial in Mopeia is that strong community engagement is essential,” states Francisco Saúte, director of the Manhiça Health Research Centre (CISM). “Building trust with local communities and fostering close collaboration with the Health Ministry, National Malaria Control Program, and local authorities was key to ensuring acceptance of the ivermectin MDA.”

Expanding the Impact Beyond Malaria

In addition to reducing malaria transmission, ivermectin MDA offers significant collateral benefits. The BOHEMIA team found an important reduction in the prevalence of skin infestations such as scabies and head lice in the ivermectin group in Mozambique, and the community reported a major reduction in bed bugs in Kenya. These effects are particularly valuable when ivermectin is integrated into existing delivery systems, maximising its impact on public health.

Shaping the future of malaria prevention

The study is part of a larger global effort to assess ivermectin’s potential in malaria control. The findings have been reviewed by the WHO vector control advisory group, which concluded that the study had demonstrated impact and recommended further studies. Findings were also shared with national health authorities as they evaluate the potential inclusion of ivermectin in malaria control programmes.

“This research has the potential to shape the future of malaria prevention, particularly in endemic areas where existing tools are failing”, concludes Regina Rabinovich, BOHEMIA PI and Director of ISGlobal’s Malaria Elimination Initiative. “With its novel mechanism of action and proven safety profile, ivermectin could offer a new approach using a well-known, safe drug that can add to the effect of other mosquito control tools available today.”