Despite technical advancements and an abundance of food globally, food security is a major ongoing challenge. Eight hundred seventy million people do not have enough to eat and undernutrition contributes to the premature deaths of over six million children annually.1 Land degradation, fresh water scarcity, overfishing, and global warming all threaten to diminish food supplies. Meanwhile, food demand is increasing due to population growth and a rising middle class in the developing world that is purchasing more foods, and more resource-intensive foods. Improved technologies have helped farmers grow more, but extreme wealth inequality still leaves the world’s poorest struggling to afford enough food. These and other trends virtually guarantee that feeding humanity will require major dedicated efforts into the future.

It is critical to keep in mind that these trends show gradual shifts in food security under otherwise “normal” circumstances. However, a range of extreme events could cause large abrupt declines in global food production from conventional agriculture.2 If one of these events occurs, humanity could face a global famine of historic proportions. The collapse of our civilization or even the extinction of the human species are possible outcomes, with other species around the world also likely to go extinct, including those that may have survived the extinction event being caused by humans that is underway now.

One major threat comes from events that block sunlight by sending large quantities of dust, smoke, or ash into the atmosphere. Sunlight could be blocked if Earth collides with a large asteroid or comet, such as the one believed to have caused the dinosaurs’ extinction, from a super volcanic eruption, such as the Toba eruption 75,000 years ago that some scientists propose almost killed off our early human ancestors,3 and also from a nuclear war, with the atmosphere coated by the ashes of incinerated cities.

Some abrupt food supply threats also come from rapid environmental change and direct threats to crops. These may not be as severe as sun-blocking catastrophes, but can still cause large and abrupt declines in food production. For example, global warming could cross thresholds in the Earth’s system,4 rapid changes and disruptions to ocean circulation could bring dramatic shifts in global weather patterns, specific crops could be threatened by natural pests, as in the Irish Potato Famine, or biotechnology could bring even more devastating engineered-crop pathogens. For comparison, biosecurity experts are actively debating the potential for certain “gain-of-function” experiments to create dangerous new pathogens that could escape from laboratories and cause deadly human pandemics,5 and similar research may be able to bring crop pandemics. And these are just some known scenarios—additional threats may lurk beyond the current horizon of scientific awareness.

A food web of alternative foods from biomass and fossil fuels.

As an illustration of how bad things could get, consider a scenario in which there is a nuclear war between India and Pakistan. Smoke from the burning cities would block sunlight across the planet and could reduce global temperatures by 1ºC for a decade.6 Crop simulations project potential global food production could decline by 20 to 50 percent.7 Combining that with existing poverty and malnourishment equals an estimated two billion people at risk of starvation.8 And that is for a war with “only” 100 nuclear weapons. A war using more of the world’s current total of 15,800 nuclear weapons would bring even worse consequences.

Solutions to Global Food Supply Catastrophes


Abrupt global food catastrophes are rare events; however, the possibility exists and if one does occur, the damages could be so large that it would merit immediate attention and quick responses. This raises the question: What solutions are available?

There are several responses to abrupt global food catastrophes. If agriculture is still possible, it can be diverted from livestock and biofuels production to foods intended for direct human consumption, keeping in mind larger catastrophes would leave less food to divert. Additional food could also come from oceans, though this is a limited option and could further threaten and deplete marine biodiversity after a period of time. Another solution is to stockpile food prior to the catastrophe, though this is expensive and can worsen pre-catastrophe food security by diverting food from regular food supplies.

In light of the enormous threat of global food supply catastrophe and the shortcomings of other solutions, we propose a new solution, to produce food with energy from sources other than the sun. Ultimately, crops do not need sunlight per se. They just need energy. We call our solution “alternative food,” because it uses alternatives to sunlight, just like alternative energy uses alternatives to fossil fuels. Alternative foods are already in limited production and could be scaled up following a major catastrophe.9 Alternative foods can play an important role in the mix of responses to a global food supply catastrophe.

The simplest type of alternative food is plants grown from artificial light. Today, indoor agriculture powered by light-emitting diodes is being explored as a solution to land scarcity and resource-intensive outdoor agriculture.10 These indoor farms could produce any of the crops currently grown around the world. However, a lot of energy is lost converting the initial energy source into electricity, then into light, then into plants. As a result, all of the world’s current electricity could feed only a small portion of the world’s population. To feed everyone, other solutions are also needed.

A better solution comes from foods powered by fossil fuels. Today, the Danish biotechnology company Unibio grows bacteria from natural gas and sells it as livestock feed.11 The same livestock could feed some people after a catastrophe. More people could be fed by adapting the Unibio process for direct human consumption—as odd as it might seem, getting food from bacteria could keep many people alive in a catastrophe. And thanks to progress in food science, the resulting foods may even taste good.

The Unibio food made from feeding natural gas to bacteria.

One might hesitate to promote foods like Unibio’s because of the environmental harms caused by fossil fuels, but this would be a mistake. Unibio’s process does release greenhouse gases, but would only do so at a large scale in the event of a food catastrophe. Instead of continuing to burn fossil fuels now, it would be much better to save them for such an event. However, if fossil fuels are needed during food catastrophes, so is the infrastructure for extracting, refining, and distributing them, but without on-going production, the infrastructure becomes defunct. In that case, there could be a difficult trade-off between avoiding fossil fuels because of global warming and keeping them around because of the risk of food catastrophes. However, some fossil fuels require less infrastructure to extract and could be more easily extracted during a food catastrophe. One example is coal deposits located near the surface, which strengthens the case for abandoning coal burning now.

However, there is a different energy source which does not require so much infrastructure: biomass. After a catastrophe, biomass would be available from surviving trees and plants. Biomass could be harvested by foraging or lumbering, though it is important to keep in mind that collecting a lot of biomass could damage ecosystems. This creates a potential trade-off, though it would only be faced in the event of a food catastrophe. Furthermore, in the event of extreme sun-blocking, some or all trees would die anyway, depending on how much light is available. This makes alternative foods from biomass an especially attractive solution in this scenario.

Biomass can be fed into the food supply in several ways, as illustrated in the food web. Wood can be fed to beetles, which can in turn be fed directly to humans. For those who don’t find beetles so appetizing, they can be fed to a more palatable intermediate species, though this would greatly reduce the amount of food available to humans. Horses, cows, goats, and sheep can be fed leaves and non-woody plants. Mushrooms can grow on many types of biomass. Finally, if woody biomass is partially consumed by mushrooms or bacteria, this could be fed to rats or even chickens.

Some plants and plant parts can be fed directly to humans. Familiar foods include nuts and edible leaves. Less familiar options could also help during a food catastrophe: some leaves (such as pine needles) can be boiled to make tea, and some biofuels turn cornstalks and other residues into sugar with enzymes that are fed to a fungus to make ethanol—and if people are short on food, they could just eat the sugar.

Ultimately, biomass foods cannot provide everything found in a grocery store, but they can keep people from starving to death. Some of these techniques can even improve food security during “normal” times, such as by feeding sawmill wood waste to mushrooms. As the food web illustrates, the waste from one organism can become the food for another organism.

The best solutions for abrupt food catastrophes will vary from place to place.12 Local social and environmental factors are important. Some places have more energy for indoor agriculture, or more biomass, or more fossil fuels. Some places have technical and political capacity that is better suited for certain solutions. Some places have cultural preferences for certain types of foods. For these and other reasons, food catastrophe solutions should be developed locally to ensure that each community has a solution that works for itself.

There is another reason to develop these solutions locally. In the aftermath of a major global catastrophe, regions could become isolated from each other. Travel, trade, and communications all depend on complex systems of infrastructure. A catastrophe big enough to damage global agriculture could also disrupt these systems, though agriculture is usually more sensitive to environmental catastrophes than most built physical infrastructure. Self-sufficient communities will be best positioned to ‘weather out the storm.’13

The Svalbard Global Seed Vault, a secure seed bank in Norway currently housing over 860,000 seed samples originating from nearly every country in the world.

Finally, the solutions presented here could also be used to protect biodiversity, which is critical in re-establishing flourishing ecosystems. Plant biodiversity is relatively easy to preserve by storing seeds, such as in the Svalbard “doomsday” seed vault, but protecting animal biodiversity is harder. For that, alternative foods can help. If no food is available in the wild, humans could divert some alternative foods to preserving nonhuman animal species. It would be impossible to keep every animal alive, but it should be possible to keep each species from going extinct. As few as 100 individuals can be enough to prevent a species from going extinct, which should be able to be fed in catastrophic conditions without any significant loss to the human food supply. Therefore, in addition to keeping many or even all humans alive, alternate foods could save most of the animal biodiversity that would have been lost in a catastrophe. Biodiversity conservation groups should thus be developing contingency plans for food catastrophes.

Everyone should hope that no abrupt global food supply catastrophe ever occurs. But while people should hope for the best, they should prepare for the worst. Alternative foods are a solution that could keep millions or billions of people alive during even the most severe food catastrophes. They require only modest advance preparation and no diverting of food into stockpiles. Indeed, alternative foods can even strengthen food security now by opening up new means for food production and using resources more efficiently. For these reasons, and given the extremely high stakes with abrupt global food supply catastrophes, we believe alternative foods are a solution well worth pursuing.


  1. UNICEF. The State of the World’s Children (UNICEF, New York, 2006).
  2. Denkenberger, D & Pearce, J. Feeding Everyone No Matter What: Managing Food Security After Global Catastrophe (Academic Press, Waltham, MA, 2014).
  3. Ambrose, SH. Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans. Journal of Human Evolution 34(6), 623–651 (1998).
  4. Lenton, TM et al. Tipping elements in the Earth’s climate system. Proceedings of the National Academy of Sciences 105(6), 1786–1793 (2008).
  5. Lipsitch, M & Inglesby, TV. Moratorium on research intended to create novel potential pandemic pathogens. mBio 5(6), e02366-14 (2014).
  6. Mills, MJ, Toon, OB, Lee-Taylor, J & Robock, A. Multi-decadal global cooling and unprecedented ozone loss following a regional nuclear conflict. Earth’s Future 2(4), 161–176 (2014).
  7. Xia, L, Robock, A, Mills, M, Stenke, A & Helfand, I. Global famine after a regional nuclear war. Earth’s Future 3(2), 37–48 (2015).
  8. Helfand, I. Nuclear famine: two billion people at risk. International Physicians for the Prevention of Nuclear War/Physicians for Social Responsibility [online] (2013).
  9. Denkenberger, DC & Pearce, JM. Feeding everyone: Solving the food crisis in event of global catastrophes that kill crops or obscure the sun. Futures 72, 57–68 (2015).
  10. Isaacson, B. To feed humankind, we need the farms of the future today. Newsweek [online] (22 October 2015).
  11. Unibio. Technology Introduction [online].
  12. Baum, SD, Denkenberger, DC Pearce, JM, Robock, A & Winkler, R. Resilience to global food supply catastrophes. Environment, Systems, and Decisions 35(2), 301–313 (2015).
  13. Maher, TM Jr & Baum, SD. Adaptation to and recovery from global catastrophe. Sustainability 5(4), 1461–1479 (2013).

Seth Baum

Dr. Seth Baum is Executive Director of the Global Catastrophic Risk Institute, a nonprofit think tank that Baum co-founded in 2011. He is also an Affiliate Scholar at the Institute for Ethics and Emerging...


David Denkenberger

Dr. David Denkenberger received his B.S. from Penn State in Engineering Science, his M.S.E. from Princeton in Mechanical and Aerospace Engineering, and his Ph.D. from the University of Colorado at Boulder...


Joshua M. Pearce

Joshua M. Pearce is an Associate Professor cross-appointed in the Department of Materials Science & Engineering and in the Department of Electrical & Computer Engineering at the Michigan Technological...

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