Welcome to the year 2170, the predictions of our grandparents were so wrong: The human population didn't cap at 20 billion, it went far past that. The global population is now roughly 200 billion.

What kind of farming practices of food creation would need to be employed to feed a population this massive? By farming practices I mean literally any sort of food creation method that can be scaled to an industrial level. E.g.: vertical farming, cultured meat, etc.


The Earth is under an unitary government so you'd have much more infrastructure than there currently is.

Big corporations are still around and I assume will probably be vital to feeding the population more than ever.

Let's not bother with the "whys" when it comes to the population. That will be a later question.

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    $\begingroup$ Not an answer as such, as I can support by data at the moment, but you would probably lose all meat from livestock: too expensive to product. We're using up to 60% of our food ressources to feed the meat. So the future with 200 billions humans is probably either vegan or cannibalistic (Hello Soylent Green, even if your maths don't hold) $\endgroup$
    – Nyakouai
    May 2, 2019 at 14:50
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    $\begingroup$ Livebred meat is inefficient compared to lab grown meat, but you also require something to "feed" the meat, so lab meat is less efficient than vegetal proteines. So my bet is on peas. Lot of peas. $\endgroup$
    – Nyakouai
    May 2, 2019 at 16:53
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    $\begingroup$ Hard to say currently we are at only 8 billion and 821 million of them are chronically malnourished... $\endgroup$
    – Rob
    May 2, 2019 at 17:03
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    $\begingroup$ Too short for an answer, but you do want to look at phosphorus as a bottleneck projectrho.com/public_html/rocket/mining.php#bottleneck $\endgroup$
    – Eth
    May 2, 2019 at 17:35
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    $\begingroup$ @Rob, that's a useful point: 10% of our world is chronically malnourished. An oversimplified straight-line analysis would suggest that 10% or 20M of his population would also be chronically malnourished. That could have substantial effects as enough people in a small area can start a rebellion. Excellent insight! $\endgroup$
    – JBH
    May 2, 2019 at 19:36

6 Answers 6


A population of 200 billion would require a significantly different approach than any ideas of bucolic farm fields. Efficiency would be paramount, with soil fertility being likely insufficient.

Cities would have combined facilities for sewage processing and vertical farming. Nutrients will need to be recycled from sewage. A series of bacterial/algal processing stages would be used to remove pathogens, clean up any toxic contamination and residual pharmaceuticals, and render it suitable as inputs for factory growing operations.

The bulk of foods will likely be derived from mass-production using yeasts and algae creating a nutrient paste. Endless vats stacked together with lighting and aeration and fed through pipes in a continuous flow - sewage in one end, nutrient paste out the other (obviously there would be some loss with sludge from unusable materials/contamination too - no system is perfectly efficient). The wealthier you are, the less of this you will likely eat, but most people will have at least some of this to pad out their diet (usually isn't meant to be eaten by itself but as just one ingredient in a dish).

Vertical farms growing higher-value produce would provide the taste and mouth-feel and simply better satisfaction of the meals. Stacked racks of plants grown under artificial lighting, fed on a nutrient flow (coming from post-treatment sewage/compost), and being the advanced form developed from the modern vertical farms you can see being developed today. These will likely be robotic facilities, so full of CO2 for faster growth (doesn't need to be breathable for humans, and lower nutrient density isn't important since those come from the nutrient paste).

They likely also have annexes for turning some of their waste into insects - something like black soldier fly larva or mealworms as protein supplements, and to feed some fish (aquaponics) or chickens for eggs. If there is a good system for collecting food waste (which there really should be), it could be used for more expensive foods like pigs raised on table/kitchen slops.

So far all of this is expandable up to any scale necessary, but some land will still be used for traditional farming. This will be a combination of having expensive "natural" foods for the affluent (not affordable to the common population beyond special occasions) and because grazing animals are great for land conservation. This makes dairy more of a special luxury product, and meat from livestock a rare delicacy, but they are unlikely to disappear entirely.


At those numbers, our most likely course of action would be to terraform earth into something far more productive...

There are massive 'dead zones' in the ocean of surprisingly low productivity regions in the oceans, and they are basically deserts due to lack of nutrients. - They're too far from land to be 'fed' by river run off, and the water is too deep for currents to raise nutrients from the ocean floor. So we can compare the productivity of these massive ocean zones, that make up some stupidly large part of the planet's surface area, to the productivity of coral reefs: The reefs make up less than 0.1% of the surface area, and yet apparently still out perform the vast majority of the oceans for energy and life...

The obvious answer would be to address that by carefully managing nutrient introduction into larger portions of the ocean, and possibly combine them with artificial islands for crop and energy production. A vastly expanded ecosystem with more bio-matter production that can be transformed into productive food systems for humans to reduce our reliance on natural habitats on land.

[Hope your population likes seaweeds and fish...]

Beyond that we would need far more 'green' city designs.

  • Large 'green roof' programs, with buildings designed to both be buildings to live and work in, and still produce food.
  • A refocus on local food production to reduce energy needs on shipping.
  • Use of vertical farming: Taking the energy that would have been expended in shipping food, and using it to power artificial lighting over fast growing leafy greens.
  • $\begingroup$ luckily a lot of taste is cultural so they'll love the taste. $\endgroup$ May 2, 2019 at 15:59
  • $\begingroup$ I'm not sure green roofs are going to help a whole lot. A totally vegetarian diet requires about 0.5 acres of farmland to feed one person for a year. New York City is about 200k acres in area, which would only feed 400k individuals, less than 5% of the city's population. Population density of cities far outstrips the number of people that could be fed using that land for crops, so no matter what you do, most city-dwellers' food has to come from somewhere else. $\endgroup$ May 2, 2019 at 18:34
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    $\begingroup$ @NuclearWang that is why you base your systems on layered solutions rather than trying to rely too heavily on one single option. Green roof designs, combined with vertical aquaponics farming solutions could allow a city of New York's density to be an EXPORTER of food... $\endgroup$ May 2, 2019 at 19:09

One non-food technique for feeding people would be to have smaller people. You can roughly double the number of people you can feed if they're smaller.

As a rough example using : https://www.freedieting.com/calorie-calculator A sedentary 30 year old male, 200LBS @ 6" tall requires 2290 calories per day A sedentary 30 year old male, 65LBS @ 4" tall requires 1100 calories per day

I did cheat a little bit with a 200LBS guy, that's a high BMI. A more trim BMI would be 145 LBS for that frame. That would bring the calorie requirements down to 1960, but that's still pretty close.


My answer to this question: How would Elves survive underground without prior experience?1

And the links to other questions and answers show that it is possible to greatly multiply food production per unit of area.

I note that 200 billion would be about 26.7 times the present population of Earth. Thus it would be necessary to increase food production by 26.7 times in 150 years. That means doubling food production almost 4 times or about once every 37.5 years.

Note that the world population doubled from 2 billion to 4 billion in 47 years from 1924 to 1974 and doubled from 3 billion to 6 billion in 39 years from 1960 to 1999, and is predicted to double from 4 billion to 8 billion in 49 years from 1974 to 2023.


I note that a population of 200 billion would have about 26.7 times the biomass of the present human species which already has a rather high percentage of the biomass on Earth. Thus vast amounts of the organic chemicals necessary for life, or the chemical elements they are composed of, might have to be imported to Earth to reduce the strain on the non human biosphere.

Fortunately the elements and compounds necessary for life are common in various comets and some types of asteroids, etc. The workers who live in outer space would have to live in enclosed habitats where everything is recycled as much as possible, and the people on Earth would probably live in similar enclosed habitats where everything is recycled as much as possible.

One way to reduce the food production necessary for 200 billion humans, and to reduce the biomass within 200 billion human bodies, would be to genetically or otherwise reduce the average size of a typical human. Reducing the mass of the average human by 10 percent would shave off ten percent of the total human biomass and the total necessary food production. Reducing the mass of the average human by 50 percent would reduce needed food production by 50 percent.

Note that tests on mice show it is possible that feeding mammals a healthy but low calorie diet may vastly increase their life spans. If this works for humans then greatly increased life spans will help accelerate population growth while the low calorie diets will result in lower average body mass.

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    $\begingroup$ Heh. Is concentrating all that carbon in human bodies a way to sequester carbon? Heh heh. $\endgroup$
    – puppetsock
    May 3, 2019 at 17:14

150 years from now...

Probably, in case of a population crisis, we will have by then all the technology necessary to artificially mass-create the food.

Think of huge factories where the basic organic substances, like organic waste, carbonate compounds and so on, will be combined with air and water. The energy will be provided by the electric grid, so that not only sunlight would provide the energy to create new biomass, but basically everything from fossil fuel to wind, tides, nuclear...
In other words, now we need (very roughly speaking) sunlight, water and soil to create food.
In the future, - and in case of a population crisis that could force mankind to find alternatives to farming - soil would be unnecessary, while sun will not be so important. The factories will be built near water bodies to have everything necessary to food production

Probably the food itself would come from cell coltures, which could be genetically altered and grown to seem meat or vegetables (as consistency and taste).


Yes but only when people:

Stop using soil.

Start using water-only vertical farms, and stop wasting farm food on animals.

Meat is energy inefficient.

For example it takes 3 times the food to produce a mammal of the same weight PER YEAR

If you wanted a 400kg cow, then you need to feed that cow 1200kg of grain every single year for 3 years and then kill it for food.

Not only do grains have more kilocalories per kilograms than meat 3780 vs 2710 so the portion that one cow eats in a year would be enough to to feed more people than the cow itself once it's killed.

But we are talking 3 years worth of food wasted which could feed an entire city, wasted on one single cow which can feed about a dozen or slightly more families.

This is really inefficient, so ditch animals all together ans use modern agricultural technologies.

Maybe leave meat only to the primitive nomads who can't figure how to grow plants.


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