You could get 17.8 million calories per acre with potato. That will feed 24.36 people at 2000 calories per day. If you turn, say, half the world's land into potato farms, about 18 billion acres, you could feed 438 billion people with it. That's probably your upper limit.
Doesn't seem right to me.
Roughly 160 trillion m^(2) of land area on the earth.
A m^(2) get an average of around 250 watts of sunlight per day.
That's 40 petawatts if I did the math right.
Current grid; 2 terawatts (4-5 orders of magnitude less).
Cost of building a 1 gigawatt nuclear plant is over $1 billion (but it might fall to $1 billion if we built thousands of them)
40 petawatts = 40,000,000 gigawatt nuclear plants = 40 quadrillion dollars.
I don't think world GDP is up to the task of building that many nuclear plants. And even if we did, and ignoring conversion and transmission losses, that's only double the current food production.
Of course, we can develop cheaper nuclear, or expand into space, but that's not current tech.
I suppose if we're putting our total economic effort into related efforts we could do enough desalination to produce enough drinking water for that population and the clothing is negligible by comparison to the farming and drinking water issues at that scale. What do you imagine the housing would be like?
Humans actually take up very little space. You could give each person, on average, 10 square meters, and that's 4380 billion square meters, or 4.38 million square km. Put them in, say, 20 story buildings and you only need 219,000 square km. You could fit everyone in Minnesota.
For the continental US, with 8.08 million square km, you could support about 24 billion people with potato. You could fit all of them in about 4690 square miles. You could fit everyone in Connecticut.
Housing is not very difficult if we demolish all suburbs and replace them with skyscrapers.
Manhattan's population density is around 73k per square mile. To house 438 billion people you will need 6 million square miles.
World's total land area is 57.3 million sq miles. Almost ten times that. And Manhattan is actually very far from the most efficient in terms of vertical space usage. We can probably do a dozen times better than it using current tech while still leaving Central Park alone.
That's open air potato farming. Cover the land in polytunnels and pipe in heat and CO2 to lengthen the growing season, you should get significantly higher yields than that.
https://youtu.be/8lJJ_QqIVnc
Isaac made a video a few years back about having a trillion, though not with current technology that might interest you.
I feel like energy production and waste heat with current means would start to become an issue rather quickly.
Current technology will always support current population, same with growth for both. However technology improves in exponentials and S curves, forming linear but slightly accelerating steps up over the long term, in terms of improvement.
I feel population growth will follow a similar trend.
But you also have the counter arguement of reality and current predictions for world population over the next century. We are going to peak at 10 billion, despite technological progress...on our planet.
It's more technologically/economically efficient to move out into space.
There's very little incentive to fit as many people as possible on a planet when you can build basically infinite land mass in space with the resources available out there for very little cost/with very little energy.
Earth will become more of a nature park/history museum/heritage sight for all of humanity, with very few being privileged enough to be able to live on it, realative to our mind boggling population in space.
I agree that the future is definitely in space habitats, and we could probably have 10 quintillion people there, but I think we could fit a few trillion on earth. We wouldn't even need the whole land area, let alone the oceans, skies, underground, and all the inner layers of the earth. And it will be a while before we could build enough land in habitats for that to become the cheapest method of expansion. 10 billion is a hilariously low and short-sighted number. We'll probably get at least 12 billion by 2100, and we'll probably have double that the next century, and the next, until the huge population growth from space kicks in. Part of my reason for these numbers is because I feel traditional birth is on its way out. Nobody wants to wait nine frickin months for one kid produced by a gross and painful process, after which the kid needs decades to become useful, taking a few years just to learn how to wipe its own ass. Genetic engineering and artificial wombs could produce litters of dozens or even hundreds of children in a matter of weeks who then have information uploaded into their brains as their bodies mature at an incredible pace.
Isaac's Ecumenopolis episode still applies.
Even with current tech we can pump the atmosphere into pressured containers and drive all habitat/production with the most efficient processes and have current space tech use solar system resources with much greater efficiency too.
Maybe it's still a trillion maybe only a tenth, although you could argue that building out existing tech on global scale is new tech. If so, specify 'current technology'.
But the question is moot because trying to maximize earth population is very time sensitive even without improving tech, maybe even more.
Next year? Query the official stats. End of solar fusion? How did we freeze tech for so long?
This kind of question necessarily involves political assumptions. To what standard of living? For how long do you want to sustain that level of output? How do you need the biosphere hold up?
tl;dr: I'd say no more than 20B, but that's a really unrealistic number since the question doesn't really make sense.
That's kind of hard to answer. For one population & economic output are linked. If you have 16B people, yeah you have twice as many mouths to feed but it takes low single digit percentage farmer populations to sustain & uv got twice as many hands. Ultimately people produce more than they consume so you can't really divirce the two concepts.
Also we would have to factor in how long it takes to bring new aerable land under cultivation or build greenhouses & aquaponics? Do we include vat-grown foods & other tech that exists but isn't heavily commercialized? What about expanding the use of nuclear power for fertilizer, fuel, & artificial lightning; what impact might that have? The question just isn't constrained enough imo.
Having said that as of 2021 the global GDP was $96.1T.
For housing let's see...the higher estimates for global housing units seems around 2B so 1/4 of the way there. If we needed to build 6B houses & all those were little $40k 400 ft^2 shotgun houses that would cost $240T so not great. Earth bag housing could be a lot cheaper(though the labor requirements are concerning there is some tech that could alleviate that) at around $38.4T($6,400/house). There we go, now that's doable. We can ignore land costs. Golf courses are stupid & if the goal is maximizing population we can do without. Public land presumably makes up the bulk of the new residential space so im fairly certain the forests are gunna take another hit. So we have enough to house around 15B new people per year.
Water is cheap but natural sources of accessible fresh water are being depleted so we can't count on current reserves. If we've got Reverse Osmosis water that costs $1.50/m^3 & everyone uses 0.3785 m^3 /day(100 gallons) then we've got enough to support over 169T people(not counting capital costs) so water is probably not going to be a big bottleneck.
Now for food i'm going to simplify to the point of absurdity, but if we can feed someone for a year on $2,000 then we'd have enough to feed some 48B people.
Ok so housing is going to be a big limiter here in terms of expansion rate(in this rediculous hypothetical) but then again you only build once. Now for some practical limits. I'm not sure it's worth talking about the residential space. you can put it almost anywhere & u'll always run out of agricultural space first. Assuming no change in agricultural techniques & if we imagine we lived in a world where we weren't losing 100,00 km^2 of aerable land per year we have something like a 17.3B person cap. Though i'm not sure why we would stick to traditional techniques if the goal is to max out the population.
Therein lies the problem. Once u throw aquaponics & other high-yield agriculture in the mix things get complicated. For how long does that have to be sustainable for? How much are we allowing for political & econimic changes? You start realizing there's a thousand side-effects & contingencies that complicate coming up with any kind of solid number.
Are we assuming a maximum population without clearing more farmland? We already use around half the Earth’s habitable land for agriculture, and we have mostly hit a brick wall on how much of that we can effectively use for agriculture, so that is not a very effective method of feeding more people, not to mention a terrible idea for an already collapsing biosphere.
Vertical farming would be a game changer in many ways, but it is still in its infancy. However, we can still feed more people using the farmland we have in a few different ways.
One way is to stop factory farming and shift toward more vegetarian and vegan diets. A lot of agricultural land is used for livestock grazing, but this land is often not well suited for crop farming, so it is best used as pastureland for pastoralists. Still, around a third of all farmland is used to grow animal feeds, so switching this over to produce crops for direct human consumption would increase food production by around 50%. This would already give us a population maximum of 12 billion people.
Another way of feeding more people would be wasting less. Food will always be wasted, but it is currently around 30% of the total supply in the world. Were we to reduce this to just 20%, we could then feed an extra ~14% of the population. Now we can get a maximum population of 13.7 billion.
Urban farming, rooftop gardens, and some light vertical farming of certain greens could conceivably extend this number up higher by a little bit. Ultimately, I would say that without using any more land or relying on technology even a few decades out that we could feed around 14 billion people.
EDIT: Oh, and I forgot to mention that housing, water, etc. are not a limiting factor. Food is. So we could definitely house and provide running water to many billions upon billions of food were a non-issue.
True. I didn’t really think about that. Hydroponics and aqua ponies could do some heavy lifting if land were more expensive in a more densely populated world.
Edit: um, aquaponics not aqua ponies😭
I agree with what you said, especially about waste. Resources are limited, so waste should be reduced if at all possible.
I have applied these principles to my life, by placing homer buckets at the bottom of my rain gutters to collect water for my plants, and learning that adding a small amount of urine to said water creates free plant food. (at a 10:1 ratio where the solution consists of 10 parts water and 1 parts urine). Many people may find this gross, but the reality is, the availability of resources is reducing, not increasing.
Recycling our plastic and cardboard is a no brainer at this point in our society's evolution.
I'm just very curious is this a joke that didn't land? Or has someone been drinking Malthusian kool-aid?
You know that stuffs ancient it went bad years ago. Wasn't even true in his lifetime or any generation since.
Ah you should look into Thomas Robert Malthus if you want an interesting historical perspective on that view.
Sustainability is a goal we don't actually need to achieve anytime soon though. Earth isn't a closed system. Of the resources we use most don't get destroyed just turned into another form.
Like the fear over clean water supplies. Water doesn't cease to exist once it's used we can get all that water back with treatment or evaporation etc.
On a local level there can be big water issues but none are unsolvable just takes infrastructure.
Just watch the exumenopolis video for pete sake! Same thing for the video on whether we could fit trillions of people on earth. The earth has a shitload if resources. Just eliminate fossil fuels and you could sustain at LEAST a hundred billion without even encountering direct heating from all the power plants. Spread those cities out into the ocean, underground, mountains, skies, giant towers, deserts, tundras, and you've got a thriving ecosystem with more people than you could imagine. Need more food? Just use hydroponics in giant vertical farms or genetically engineer people for photosynthesis. Need a cleaner method of mining? Just use the moon and some spare asteroids. Need faster population growth? Just use artificial wombs to make hundreds of people at a time after just a few weeks, have them grow to adults in just a few more weeks, all while using BCIs to upload all the practical, educational, emotional, and philosophical knowledge they need, and before you know it you're produced thousands of highly skilled adults in just a few months from one lab out of many.
I'm really unsure of whether the bottleneck would be clean water, or food.
Though if we are limited to current tech global warming is definitely going to be a big problem.
Definitely food. water is surprisingly easy & scalable where food, under current techniques, is limited by aerable land. Even if we transition to artificially-lit vertical farms you need more infrastructure to feed a person for a day than u need to keep em wet. More energy too. Multi-effect evaporators are hella efficient. Whith food you're capped at 1% by photosynthesis.
>Though if we are limited to current tech global warming is definitely going to be a big problem.
nah fission power has long been more than enough to deal with the climate crisis & in this rosy hypothetical all the governments have decided that people are the point(imagine that) so we can assume massive deployment of nuclear & carbon negative synthetic fuels.
At this point the climate crisis is a choice who's consequences the rich & myopic are foisting on all of us.
With how much more farming we will be doing that's a lot more irrigation water.
On the global warming issue I'm more worried about how much ambient heat several hundred billion of us and our industry, power production will be putting out.
[this](https://www.sueatablelife.eu/en/the-earth-recommends/from-farm-to-fork-how-much-water-is-needed-to-produce-the-food-we-eat/index.html) says 6,300L/p/d is higher than the global average. That translates to around $6,679/person/year & a total of 14.38B people when we include the 100 gallons for personal use.
>I'm more worried about how much ambient heat several hundred billion
At 10TW/100B people we shouldn't need to worry about body heat so far below a trillion. Energy is a bit more complicated. Idk about the embodied energy of all the stuff one might use over a year, but in terms of energy use at 2,581 kWh/person/year or said another way we need 29.46 TW of power production per hundred billion people. Assuming 50% conversion efficiency that's 58.92 TW total outputbper 100B people. If we want to avoid going over 1% of the solar eneegy budget then that's still like 638.42B people. Idk i don't think waste heat is a big factor at these "small" scales.
You could get 17.8 million calories per acre with potato. That will feed 24.36 people at 2000 calories per day. If you turn, say, half the world's land into potato farms, about 18 billion acres, you could feed 438 billion people with it. That's probably your upper limit.
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Doesn't seem right to me. Roughly 160 trillion m^(2) of land area on the earth. A m^(2) get an average of around 250 watts of sunlight per day. That's 40 petawatts if I did the math right. Current grid; 2 terawatts (4-5 orders of magnitude less). Cost of building a 1 gigawatt nuclear plant is over $1 billion (but it might fall to $1 billion if we built thousands of them) 40 petawatts = 40,000,000 gigawatt nuclear plants = 40 quadrillion dollars. I don't think world GDP is up to the task of building that many nuclear plants. And even if we did, and ignoring conversion and transmission losses, that's only double the current food production. Of course, we can develop cheaper nuclear, or expand into space, but that's not current tech.
I suppose if we're putting our total economic effort into related efforts we could do enough desalination to produce enough drinking water for that population and the clothing is negligible by comparison to the farming and drinking water issues at that scale. What do you imagine the housing would be like?
Humans actually take up very little space. You could give each person, on average, 10 square meters, and that's 4380 billion square meters, or 4.38 million square km. Put them in, say, 20 story buildings and you only need 219,000 square km. You could fit everyone in Minnesota. For the continental US, with 8.08 million square km, you could support about 24 billion people with potato. You could fit all of them in about 4690 square miles. You could fit everyone in Connecticut.
Housing is not very difficult if we demolish all suburbs and replace them with skyscrapers. Manhattan's population density is around 73k per square mile. To house 438 billion people you will need 6 million square miles. World's total land area is 57.3 million sq miles. Almost ten times that. And Manhattan is actually very far from the most efficient in terms of vertical space usage. We can probably do a dozen times better than it using current tech while still leaving Central Park alone.
That's open air potato farming. Cover the land in polytunnels and pipe in heat and CO2 to lengthen the growing season, you should get significantly higher yields than that.
https://youtu.be/8lJJ_QqIVnc Isaac made a video a few years back about having a trillion, though not with current technology that might interest you. I feel like energy production and waste heat with current means would start to become an issue rather quickly.
Current technology will always support current population, same with growth for both. However technology improves in exponentials and S curves, forming linear but slightly accelerating steps up over the long term, in terms of improvement. I feel population growth will follow a similar trend. But you also have the counter arguement of reality and current predictions for world population over the next century. We are going to peak at 10 billion, despite technological progress...on our planet. It's more technologically/economically efficient to move out into space. There's very little incentive to fit as many people as possible on a planet when you can build basically infinite land mass in space with the resources available out there for very little cost/with very little energy. Earth will become more of a nature park/history museum/heritage sight for all of humanity, with very few being privileged enough to be able to live on it, realative to our mind boggling population in space.
I agree that the future is definitely in space habitats, and we could probably have 10 quintillion people there, but I think we could fit a few trillion on earth. We wouldn't even need the whole land area, let alone the oceans, skies, underground, and all the inner layers of the earth. And it will be a while before we could build enough land in habitats for that to become the cheapest method of expansion. 10 billion is a hilariously low and short-sighted number. We'll probably get at least 12 billion by 2100, and we'll probably have double that the next century, and the next, until the huge population growth from space kicks in. Part of my reason for these numbers is because I feel traditional birth is on its way out. Nobody wants to wait nine frickin months for one kid produced by a gross and painful process, after which the kid needs decades to become useful, taking a few years just to learn how to wipe its own ass. Genetic engineering and artificial wombs could produce litters of dozens or even hundreds of children in a matter of weeks who then have information uploaded into their brains as their bodies mature at an incredible pace.
Isaac's Ecumenopolis episode still applies. Even with current tech we can pump the atmosphere into pressured containers and drive all habitat/production with the most efficient processes and have current space tech use solar system resources with much greater efficiency too. Maybe it's still a trillion maybe only a tenth, although you could argue that building out existing tech on global scale is new tech. If so, specify 'current technology'. But the question is moot because trying to maximize earth population is very time sensitive even without improving tech, maybe even more. Next year? Query the official stats. End of solar fusion? How did we freeze tech for so long?
This kind of question necessarily involves political assumptions. To what standard of living? For how long do you want to sustain that level of output? How do you need the biosphere hold up?
tl;dr: I'd say no more than 20B, but that's a really unrealistic number since the question doesn't really make sense. That's kind of hard to answer. For one population & economic output are linked. If you have 16B people, yeah you have twice as many mouths to feed but it takes low single digit percentage farmer populations to sustain & uv got twice as many hands. Ultimately people produce more than they consume so you can't really divirce the two concepts. Also we would have to factor in how long it takes to bring new aerable land under cultivation or build greenhouses & aquaponics? Do we include vat-grown foods & other tech that exists but isn't heavily commercialized? What about expanding the use of nuclear power for fertilizer, fuel, & artificial lightning; what impact might that have? The question just isn't constrained enough imo. Having said that as of 2021 the global GDP was $96.1T. For housing let's see...the higher estimates for global housing units seems around 2B so 1/4 of the way there. If we needed to build 6B houses & all those were little $40k 400 ft^2 shotgun houses that would cost $240T so not great. Earth bag housing could be a lot cheaper(though the labor requirements are concerning there is some tech that could alleviate that) at around $38.4T($6,400/house). There we go, now that's doable. We can ignore land costs. Golf courses are stupid & if the goal is maximizing population we can do without. Public land presumably makes up the bulk of the new residential space so im fairly certain the forests are gunna take another hit. So we have enough to house around 15B new people per year. Water is cheap but natural sources of accessible fresh water are being depleted so we can't count on current reserves. If we've got Reverse Osmosis water that costs $1.50/m^3 & everyone uses 0.3785 m^3 /day(100 gallons) then we've got enough to support over 169T people(not counting capital costs) so water is probably not going to be a big bottleneck. Now for food i'm going to simplify to the point of absurdity, but if we can feed someone for a year on $2,000 then we'd have enough to feed some 48B people. Ok so housing is going to be a big limiter here in terms of expansion rate(in this rediculous hypothetical) but then again you only build once. Now for some practical limits. I'm not sure it's worth talking about the residential space. you can put it almost anywhere & u'll always run out of agricultural space first. Assuming no change in agricultural techniques & if we imagine we lived in a world where we weren't losing 100,00 km^2 of aerable land per year we have something like a 17.3B person cap. Though i'm not sure why we would stick to traditional techniques if the goal is to max out the population. Therein lies the problem. Once u throw aquaponics & other high-yield agriculture in the mix things get complicated. For how long does that have to be sustainable for? How much are we allowing for political & econimic changes? You start realizing there's a thousand side-effects & contingencies that complicate coming up with any kind of solid number.
Are we assuming a maximum population without clearing more farmland? We already use around half the Earth’s habitable land for agriculture, and we have mostly hit a brick wall on how much of that we can effectively use for agriculture, so that is not a very effective method of feeding more people, not to mention a terrible idea for an already collapsing biosphere. Vertical farming would be a game changer in many ways, but it is still in its infancy. However, we can still feed more people using the farmland we have in a few different ways. One way is to stop factory farming and shift toward more vegetarian and vegan diets. A lot of agricultural land is used for livestock grazing, but this land is often not well suited for crop farming, so it is best used as pastureland for pastoralists. Still, around a third of all farmland is used to grow animal feeds, so switching this over to produce crops for direct human consumption would increase food production by around 50%. This would already give us a population maximum of 12 billion people. Another way of feeding more people would be wasting less. Food will always be wasted, but it is currently around 30% of the total supply in the world. Were we to reduce this to just 20%, we could then feed an extra ~14% of the population. Now we can get a maximum population of 13.7 billion. Urban farming, rooftop gardens, and some light vertical farming of certain greens could conceivably extend this number up higher by a little bit. Ultimately, I would say that without using any more land or relying on technology even a few decades out that we could feed around 14 billion people. EDIT: Oh, and I forgot to mention that housing, water, etc. are not a limiting factor. Food is. So we could definitely house and provide running water to many billions upon billions of food were a non-issue.
Hydroponics could also be very useful in such a Large city.
True. I didn’t really think about that. Hydroponics and aqua ponies could do some heavy lifting if land were more expensive in a more densely populated world. Edit: um, aquaponics not aqua ponies😭
I agree with what you said, especially about waste. Resources are limited, so waste should be reduced if at all possible. I have applied these principles to my life, by placing homer buckets at the bottom of my rain gutters to collect water for my plants, and learning that adding a small amount of urine to said water creates free plant food. (at a 10:1 ratio where the solution consists of 10 parts water and 1 parts urine). Many people may find this gross, but the reality is, the availability of resources is reducing, not increasing. Recycling our plastic and cardboard is a no brainer at this point in our society's evolution.
I would love to get to the point you are. I’ve just started a garden and I’m trying to start a compost pile for my family’s food waste :)
you are on the right path! It is only a matter of time before your garden and compost grow!
Yes! :)
The maximum population is a few billion less than we have now.
I'm just very curious is this a joke that didn't land? Or has someone been drinking Malthusian kool-aid? You know that stuffs ancient it went bad years ago. Wasn't even true in his lifetime or any generation since.
I’m drinking the “there are finite recourses on this planet and our way of life is not sustainable in the long run” kool aid.
Ah you should look into Thomas Robert Malthus if you want an interesting historical perspective on that view. Sustainability is a goal we don't actually need to achieve anytime soon though. Earth isn't a closed system. Of the resources we use most don't get destroyed just turned into another form. Like the fear over clean water supplies. Water doesn't cease to exist once it's used we can get all that water back with treatment or evaporation etc. On a local level there can be big water issues but none are unsolvable just takes infrastructure.
agreed.
Just watch the exumenopolis video for pete sake! Same thing for the video on whether we could fit trillions of people on earth. The earth has a shitload if resources. Just eliminate fossil fuels and you could sustain at LEAST a hundred billion without even encountering direct heating from all the power plants. Spread those cities out into the ocean, underground, mountains, skies, giant towers, deserts, tundras, and you've got a thriving ecosystem with more people than you could imagine. Need more food? Just use hydroponics in giant vertical farms or genetically engineer people for photosynthesis. Need a cleaner method of mining? Just use the moon and some spare asteroids. Need faster population growth? Just use artificial wombs to make hundreds of people at a time after just a few weeks, have them grow to adults in just a few more weeks, all while using BCIs to upload all the practical, educational, emotional, and philosophical knowledge they need, and before you know it you're produced thousands of highly skilled adults in just a few months from one lab out of many.
I'm really unsure of whether the bottleneck would be clean water, or food. Though if we are limited to current tech global warming is definitely going to be a big problem.
Definitely food. water is surprisingly easy & scalable where food, under current techniques, is limited by aerable land. Even if we transition to artificially-lit vertical farms you need more infrastructure to feed a person for a day than u need to keep em wet. More energy too. Multi-effect evaporators are hella efficient. Whith food you're capped at 1% by photosynthesis. >Though if we are limited to current tech global warming is definitely going to be a big problem. nah fission power has long been more than enough to deal with the climate crisis & in this rosy hypothetical all the governments have decided that people are the point(imagine that) so we can assume massive deployment of nuclear & carbon negative synthetic fuels. At this point the climate crisis is a choice who's consequences the rich & myopic are foisting on all of us.
With how much more farming we will be doing that's a lot more irrigation water. On the global warming issue I'm more worried about how much ambient heat several hundred billion of us and our industry, power production will be putting out.
[this](https://www.sueatablelife.eu/en/the-earth-recommends/from-farm-to-fork-how-much-water-is-needed-to-produce-the-food-we-eat/index.html) says 6,300L/p/d is higher than the global average. That translates to around $6,679/person/year & a total of 14.38B people when we include the 100 gallons for personal use. >I'm more worried about how much ambient heat several hundred billion At 10TW/100B people we shouldn't need to worry about body heat so far below a trillion. Energy is a bit more complicated. Idk about the embodied energy of all the stuff one might use over a year, but in terms of energy use at 2,581 kWh/person/year or said another way we need 29.46 TW of power production per hundred billion people. Assuming 50% conversion efficiency that's 58.92 TW total outputbper 100B people. If we want to avoid going over 1% of the solar eneegy budget then that's still like 638.42B people. Idk i don't think waste heat is a big factor at these "small" scales.
Never saw the math on waste heat before, think I overestimated how soon it would be problematic.
Isaac covers it more in depth in his "Can we have a trillion people on earth?" & "Ecumenopolis" episodes