Significant Food Production Loss

Several human-caused and natural catastrophes could cause a significant disruption to our food production capability.

We estimate that these catastrophes could cause between a 3 – 30% reduction in our food production capacity. All of the disasters in living memory are less than 3% loss. On this page we will first discuss the catastrophes and then talk about what to do if one strikes.

Types of Catastrophes

Volcanic Eruption

A large enough volcanic eruption can spew vast quantities of smoke and debris into the atmosphere, blocking the sun, reducing rain, and causing temperatures to drop. This was seen in 1816, which was known as the year without a summer and famine occurred in parts of Europe.

Extreme Weather Events

Climate change is increasing the likelihood of more extreme weather events: droughts, heat waves, floods, fires, etc. According to a UK government study, a 10% agricultural shortfall has about an 80% chance of occurring this century.

Asteroid Impact

A medium-sized asteroid or comet could throw enough dust into the upper atmosphere to reduce sunlight, rain, and temperatures for several years.


A “super weed” like this Kudzu could outcompete crops. Super weeds can take root as a result of careless or unintentional human activity, but they could also result from a coordinated terrorist attack.

Super Crop Disease

A super crop disease could reduce global food output by 10%. If the disease affected the entire grass family, which includes corn, wheat, rice, and grass for grazing, this would account for more than half of our food. Such a virus or bacteria could spread  quickly if it were the result of a coordinated terrorist attack.

Super Crop Pest

A super crop pest, like an insect or rodent, could be resistant to pesticides and cause global damage. If it were part of a terrorist attack, it could be introduced in multiple places at once, meaning much faster damage. In general, we are more concerned with engineered animals than natural ones because engineered ones could be optimized for damage.

Microorganism Death

Plants benefit from helpful microorganisms. It is possible that something could destroy these beneficial bacteria and fungi.

Pollinator loss

Animals (bees, bats, etc.) pollinate 3-8% of our food. If they died out quickly, it would be a significant shock.

Abrupt Climate Change

Many times in the past, a continent has seen a temperature drop of approximately 18°F (10oC) in a decade, which is known as “abrupt climate change.”

Regional Nuclear War

A regional nuclear war could cause a 10 to 20% global food production loss. This is due to smoke from burning cities getting into the upper atmosphere, which could stay there for a decade. This would reduce sunlight, rain and temperatures. It also would create a near global ozone hole which would allow more ultraviolet radiation to reach the ground.

Extreme Global Warming

It is possible that there will be more than 9°F (5oC) global warming. This could make agriculture virtually impossible in the tropics, and it could reduce global food production by more than 10%. This is a slower process that would likely take about 100 years, so there would be some time to prepare.


A pandemic like the 1918 Spanish flu would not affect food production directly. However, countries may close borders to prevent the spread of the disease, so food importing countries would be in trouble. The end result could be similar in impact to a global 10% reduction in food production.

What to do if we experience a global catastrophe

The catastrophes above are among the risks that could cause major disruption to global food production. However there is hope. Most of the infrastructure would remain intact and there are many actions both governments and individuals can take to ensure people get the food that they need. Below is an outline of strategies for producing more food in a catastrophe. Generally what is needed in the significant food shortfalls is “alternate feed,” that is providing different sources of food for animals than human edible food. But depending on cooperation between countries, and more interventions may be required. Here’s a picture of the “alternate” food web:

 Alternative Food Web, where the flows of food (solid arrows) and waste (dotted arrows) are shown. In a traditional food web, it is continuously being powered by the sun. In the alternate food web, the sources are stored plants and fossil fuels.

Alternative Food Web, where the flows of food (solid arrows) and waste (dotted arrows) are shown. In a traditional food web, it is continuously being powered by the sun. In the alternate food web, the sources are stored plants and fossil fuels.

Individual and Community Actions:

Doing things on the small scale can help. You may be able to grow mushrooms in your home, harvest wild plants for tea, and/or process leaves for nutrition on the small scale. Maintain livestock that you have that can eat food inedible to humans. Dry and store meat from livestock that eats food edible to humans. It may be a lot of work to dry meat from livestock, especially if you have a large farm. Getting help from your community in exchange for food may be a good investment.

Mushrooms & Acquiring Spores:

Mushroom growing kits can be purchased, but that may not be an option in a catastrophe. The mushrooms we eat contain the spores that make other mushrooms grow. To get the spores you will need to make a spore print by placing a mushroom with the gills down on a piece of paper and covering with a bowl. Leave it for 24 hours. Fresh mushrooms are more likely to have spores than store-bought ones. The paper with the spore print can be planted in a growing substrate.

There is a variety of advice on growing mushrooms online and best practices may vary by type of mushroom. Generally you want a few things.

  • Substrate – You can grow mushrooms on any manner of woody material (whole logs, chipped wood, sawdust, hay, etc.).
  • Spread your mushroom spores (like seeds) around the substrate.
  • Keep the substrate moist. It is even better if you can keep the air around the mushrooms humid.
  • Keep out of direct sunlight.

Leaf Concentrate (small scale):

Plants for TeaWhat plants are good for tea will depend on your location. DO NOT consume a plant if you do not know if it is safe. This list is of plants that have been reportedly eaten by people.

  1. Collect Leaves from crops or trees (list of plants eaten by people).
  2. Wash leaves to remove dust and dirt.
  3. Cut or tear leaves into finger sized pieces or smaller.
  4. Grind the leaves to a pulp (can be done in a variety of ways).
  5. Press as much juice as you can from the leaf pulp.
  6. Heat the juice to boiling.
  7. Separate the curd that rises to the top of the juice with a tightly woven cloth.
  8. Press as much liquid as you can out of the cloth.
  9. The remaining matter in the cloth is leaf concentrate.
  10. Dry the leaf concentrate or preserve it in other ways (such as mixing with sugar or salt). 
  11. The remaining juice can be mixed with the fiber to make animal feed.
  12. Eat – the leaf concentrate can be eaten directly or mixed with other foods.

Dry Meat (FAO meat drying instructions):

  1. Hot air oven drying: In this household level method, the meat strips are placed on wire oven shelves at temperatures of 160-222°F. Oven doors are partially left open to allow moisture from the meat to escape. The products are dried to approx. 65% moisture loss, which takes 6-8 hours
  2. Sunlight drying (if you are in a location still getting sunlight): Cut meat into thin (half an inch (1-2 cm) width) strips. They can be dipped in a salt solution (14%). Hang on a rack to dry. You want to make sure the drying is finished in 8-10 hours which will not be possible in many areas with less sunlight so oven or other hot air drying methods are preferred for this scenario.

How to conserve your energy

There are also some behavioral things you can do to decrease calorie use. We recommend these actions because they are a way to decrease the amount of food people need to eat. We know some of these are difficult and won’t be possible for everyone.

BehaviorsHow They Help
Reduce smoking as much as possibleReduces metabolism
Sleep more: at night and take more napsConserves energy, reducing food requirements
Reduce food intake and target the lower end of normal body weight* for your heightBy targeting the lower end of normal body weight you will be able to save more food
Reduce caffeine consumptionReduces metabolism, aids sleeping
Limit sports and other unnecessary physical activity Any calories you are burning are calories that will have to be restored by eating food
Reduce alcohol consumption to a minimum Alcohol consumption can be harmful to metabolic processes and can contribute to malnutrition
Raise indoor temperatures Reduces metabolism
Reduce food to pets Make pet food last longer or allow use of pet food by humans

What to do if there is a significant loss of food production

Protect food storagePeople short on food may be desperate to acquire food from others.
Collect leaves from crops and trees that were alive at the beginning of the catastrophe and get food from them at small or large scaleNutritious food can be extracted from edible leaves using this process for the small scale, or this one for large scale.
Convert leaf remains into edible sugar. This is already being done for biofuels so the process could be adapted.Adapting from biofuels is a quick way to turn more production towards food. Other chemical plants could be retrofitted.
Don’t kill animals that can eat fiber (cows, sheep, goats, horses, deer, rabbits, etc.) and instead feed them leaves that have been shed from trees (leaf litter) and other wastes.Animals that can eat fiber are one way to turn food that can’t be eaten by humans into animals that can be eaten by humans. The larger of these animals can be used for farming.
Get some bacteria that can eat natural gas. You might be able to grow these bacteria in breweries or chemical plants.Bacteria can be grown for animal feed (or human food if you can further process it).
Grow mushrooms on wood and wastes that cannot be turned into food other ways.This is a good way to process woody material into food.
Make flour from fiber-eating insects grown on wood and other wastes. Grinding insects into flower can make them palatable and can process fibrous material into food.Grinding insects into flower can make them palatable and can process fibrous material into food.Grinding insects into flour can make them palatable and insects can process fibrous material into food.
Increase fishing. Many of the catastrophes would cool the climate, which would cause surface water in the ocean to sink, bringing nutrient rich water to the surface. A lot of algae will grow that fish can feed on, so fish would continue to be an available resource.
Dry food to preserve it and reduce shipping weight.This makes food last longer and makes it much easier to transport to high need places.
Eat a variety of foods and try to increase supplements/fortification.This helps maintain good nutrition. Ensuring good health is important given that medicine will likely be stretched.
Eat all edible parts of foods and plan ahead. This reduces food waste, allowing the same amount of food production go further.
Stop turning food into biofuels. A quick way to convert more production to human food.
Kill the animals that cannot eat fiber (chickens, turkeys, pigs, etc) that can’t be fed waste food from humans so they don’t consume human edible food and preserve the meat. We don’t want livestock eating food that could otherwise be consumed by people. Fiber-eating livestock is preferable to save.

Government, Corporation and Large Scale Actions

In large scale disasters, governments and corporations have a lot of power to mitigate damage. Managing infrastructure and helping distribute necessary resources is essential to helping keep people alive and maintaining order in a disaster. This document provides a number of strategies; not all will work for everyone. There are many ways of creating the necessary calories to survive that could be done on a large scale.

Fiber Supply for Conversion to Food:

  1. Collect dry fibrous biomass: This can be logging wastes, farming wastes and leaf litter (leaves shed by trees).
  2. Chip the larger fibrous biomass – Chipping vegetation and branches would require only a small percentage of humanity’s energy use. Vehicles and factories could be retrofitted to this purpose.
  3. The chipped biomass has a variety of possible uses:

Growing mushrooms for human consumption (can also be grown on whole logs).

Wood chips that have been partially digested by mushrooms can be fed to ruminants such as cattle, sheep, and goats.

Cellulose-digesting beetles could be used for human consumption. This is less palatable to most people, but the beetles could be ground into high protein flour.

Bacteria could be used to process the cellulose to make it digestible by various animals which could then be eaten by humans e.g. fish or chickens.

It would generally be best to slaughter and preserve the meat of livestock that cannot digest cellulose. This would help ensure that food that humans can eat goes to humans, not livestock. Drying would be the best way of preserving the meat, as that makes it easier to transport.

Bacteria Processing of Natural Gas:

Bacteria that digest methane are already being used to as high protein feed for livestock. This can be done both with natural gas harvested from fossil fuels and with natural gas from manure. Unibio has one industrial method already and more could be developed, or industrial capacity for making protein for animal feed (or human food if further processed) could be increased. You can read about Unibio’s Process here.

The above methods of food would take about a year to ramp up. Below are additional methods that could help in the short term.

Stopgap Food Production

Leaf Concentrate

Leaf concentrate can be made from any edible plant material. The process of making leaf concentrate separates the nutrients from the indigestible fiber. The instructions here are for an industrial scale, but this can also be done on a small scale. 20 pounds (10 kg) of dry leaves produce about 2 pounds (1 kg) of dry leaf concentrate, which can feed a person for a day. Industrial scale steps:

  1. Gather large amounts of edible plant material (can be wild or from farmed plants like alfalfa).
  2. Pulp the plants and press the liquid out.
  3. Heat the pressed liquid to 185-194oF (85-90oC) by steam injection. This causes coagulation of much of the protein.
  4. Remove the coagulated material (green curd) from the liquid. This is the leaf concentrate that will eventually be eaten. Separation can be achieved by centrifuge.
  5. Dry the green curd (leaf concentrate).
  6. The leaf concentrate can be ground into leaf meal for human food. This can be eaten directly or used as an ingredient in other foods. Add 1/10 of a teaspoon (500 mg) ascorbic acid (Vitamin C) per 2 pounds (1 kg) of leaf concentrate.
  7. The remaining brown juice (what’s left over once the curd is removed) can be remixed with the fibrous material, dried, and pelleted for animal feed (cattle, rabbits, etc.); or fed into an industrial process to produce sugar for humans.


Mushrooms are a good source of food because they can grow on many waste products. Using approximately one third of existing building space mushrooms could be grown indoors on dead leaves, etc and theoretically produce enough for all food needs in the short term. The use of indoor space could be reduced by using caves, mines, and temporary structures.

Bacteria grown on thin biomass (leaves, needles, and thin branches)

Given favorable conditions, bacteria have fast doubling times. Bacteria that secrete cellulase (enzyme that breaks fiber into sugar) can be grown on sheets of chipped or ground wood. The sugar could be leached out by running water over the sheets. This would be a good source of calories, but not nutrition. Nutritional supplements could be distributed and recommendations could go out to the public to make tea from edible plants and chew plant material, but spit out the fiber. This method has additional benefits. Mushrooms can be grown on leftover material and mushroom digested material can be fed to livestock.


Facing a large scale disaster is never going to be easy. There will be many challenges if such a disaster occurs, but with knowledge and preparation, these problems can be faced.  Making plans and preparations for large scale disasters now is the best way to ensure they do as little damage as possible. At the higher level, this means knowing which branches of government and organizations do what in the case of a large scale disaster. Storing food in your home or setting up communal food stores will help in short term disasters and in transitioning to new food supplies. If plans are made before a disaster, many lives could be saved.

Key Resource

Feeding Everyone: Solving the Food Crisis in the Event of Global Catastrophes that Kill Crops or Obscure the Sun
D. Denkenberger and J. Pearce.
Futures, Vol 72, 57-68, 2015.