Goal : cram as many healthy, living humans onto the Earth as possible.
Guidelines : you can use any technology that exists in at least working prototype form. This means, for instance, you can use a nuclear breeder reactor for energy, but not a nuclear fusion reactor. You can grow food using LED or OLED lamp hydroponic greenhouses or algae tanks or meat in a bioreactor, but no nanotechnology making the food Star Trek style.
Each human needs a minimum of 100 square feet of personal space, and at least 500 square feet total space including hallways, workout, and other public spaces, with a 10 foot ceiling.
Every human can be educated to the best of their personal ability in current knowledge, but no further.
All resources to do this must come from the earth itself - no mining asteroids or the Moon.
I personally think the limit is at least 1 trillion, but I would like to hear your answers. I can show my work after I hear yours.
10,000 years is long enough to be a valid solution.
This question does have a factual answer, and I can show work. It is a simple and straightforward extrapolation from known resources and technology. The answer is factual and not opinion in the same way that saying “we can send rockets to pluto using known metal and oil reserves” is also an undisputed factual possibility, even though the interest in doing so is not there.
I’ll agree that there is really no factual answer. There is nothing like a “simple and straightforward extrapolation” unless you want to assume away all environmental, societal, political and cultural feedback.
I’m sure you can get answer if you say, we have X amount of iron ore, Z amount of petroleum, etc, and with this we can make Q amount of dwellings units. Of course the rate of dwelling units depends on what you deem acceptable. Are we talking concrete pods with feeding and waste tubes or are their, you know, things that humans place in their dwellings which consume resources.
And I guess you can call that a factual answer but it has nothing to do with the human population capacity of the earth because of, well, you know, humans. You’ll end up with a population capacity for bipedal organic units massing out at an average of 80 kilos which mostly inhabit 10 ft. by 10 ft. pods with an additional 400 sq. ft of space for other things.
I agree that short term vs long term capacity is a major issue. World population may already be above our long term capacity. We’re growing food using fertilizer made out of fossil fuels. There’s a finite supply of fossil fuel and therefore a finite supply of fertilizer under existing technology. Without fertilizer, we don’t have the technology to produce enough food for seven billion people.
With current technology we can make floating islands in the oceans to live on, and underwater and underground habitats as well. So there’s no shortage of living space, the question here is about food production. Going underground or with the potential of nearly unlimited power from thousands of nuclear plants we can also grow underground and underwater, with year round heating and lighting. A trillion people sounds possible, but it’s hard to imagine the kind of political will needed for people to invest in such a situation. We would be terraforming the earth on an epic scale, and doing it with a current level of technology that will consume almost all our resources in the effort. Unrestrained population growth will more likely limit itself through war and starvation. But with some technological advancements it is probably what would happen, with strong AI and self replicating machinery there will be little man-power involved in the effort and in that case perhaps not enough political will to stop it from happening.
The fertilizer is a good point, but we can grow a lot of food without the need for artificial fertilizers. We may have to dedicate a significant portion of agricultural production towards making more fertilizer, but assuming we don’t run out of resources at 1 trillion and 1 people then we ought to be able to make the system self-sustaining. At that density I think sociological and economic problems will be a much greater problem than returning to lower yield crop production.
On the other hand, the lack of such fertilizers could be the limiting factor far below the 1 trillion number. I’m not sure how well we could be doing with the earth’s current population if not for the great improvements in agricultural production in recent times.
How Many People Can the Earth Support? by Joel E. Cohen gives a history of estimating population growth and total world capacity that included apparently every major attempt starting with van Leeuwenhoek. His list goes from 1 billion, obviously superseded, to 1 trillion. Whether that could last 10,000 years is unclear. The real world political progression to such a society is also unclear.
Well, if we can use any existing technology and cost isn’t a factor then we have a whole solar system worth of resources, so I’d say pretty much in the 10’s of billions and should have no problem with 10k years of that.
A lot of the technology required to exploit the Solar System doesn’t currently exist, and neither does the technology required to grow enough algae/fungus/yeast to feed a trillion people. However I would expect this sort of technology to be achievable within 100 years or less, assuming we start the development cycles now.
In other words - we could support a trillion people on our planet given technology we could probably have a hundred years from now. What we couldn’t do is support a diverse natural biosphere as well.
If we dispense with nuclear energy, then our energy budget is limited to insolation: the amount of energy we get from the Sun. The math on that has been done; there’s even a Kurt Vonnegut short story about it, though we may have a better understanding of human body energy requirements. I don’t recall the number, or even the name of the short story but perhaps someone else here can shed some light.
Is there a good estimate of the amount of fissile material, and how long the supply would last?
These would be gross theoretical upper bounds; clearly we won’t be anywhere near 100% efficient.
Humans don’t need much to live. We need food, water, public health, basic personal health care, protection from the elements, protection from physical damage, etc. I think that makes up most of it.
The main limiting factor is food. However much of the world’s farmland isn’t used or is used poorly. Or it is used for reasons other than feeding humans like feed for livestock or industrial purposes. Or it is used to grow foods with a low amount of calories per acre.
I can’t find it now, but there was a website that talks about what would happen if all the farmland on earth was used, it was used at western levels of productivity, it was used to grow crops with high calories/acre (I believe corn) and if 100% of it was used to feed people. I don’t recall the numbers but they were in the tens if not over a hundred billion people.
However, I don’t know how long the land could support that lifestyle.
I once read if we were still engaged in hunter gatherer lifestyles the world’s population limit would be about 250 million.
Nope that is what bipedal biological units need. At best it is what individual humans or small groups of humans need.
When you start talking about collections of humans (i.e., society) you need all kinds of organizational structures (politics), systems of value exchange (economics), means for explaining/justifying life (culture/religion) and the ability to create/modify things (science/technology).
The reason that farmland isn’t being well used or food evenly distributed is precisely because of this stuff. Sure, if you just want to do some simply math you can come up with a population number but this math is meaningless.
Well, I won’t say indefinitely, as there is desertification going on as well as soil salinization going on, but you have to look at it in perspective. Currently, with 7 billion people, the limiting factor isn’t the amount of food, but instead logistics and distribution along with the inability to control thugs in certain remote parts of the world and the inability to convince local farmers in some parts to adopt more modern practices, techniques and systems (well, and things like the European aversion to genmod crops and such, but we won’t go there). Food is produced extremely cheaply…in fact, the US actually holds back farmers from production through market forces. The US and other countries could easily ramp up food production if they wanted too. Assuming you could fix the logistics and distribution issues, as well as the thuggery and education issues, I’d say the actual limiting factor is potable water…and this is, again, something that could be fixed if the need arose. Even leaving aside the vast extraterrestrial sources of water, the Earth itself is mostly water, and making it potable is engineering and energy (and funding/capital of course).
I hear all the people in world would fit in the state of Taxes using Los Angeles density.
Now using density of suburb would not fit in size of US.
I hear there is enough food and water to go around for all now :eek::eek:but we have major distribution problem and why many people lack food and water.
That is a complete non-issue. We don’t use hydrocarbons as feedstock for fertiliser because it’s necessary,we use it because it’s cheap. And not a lot cheaper either, cents on the dollar cheaper. We could just as easily use garbage as the feedstock. In fact in a densely populated world the ability to recycle waste would be essentially, so it would be considerably cheaper and and more energy efficient to use waste for the feedstock rather than hydrocarbons.
In short, lack of hydrocarbons for fertiliser simply isn’t a limitation on growth, in the current world or the hypothetical.
In terms of density … LA maybe not, but NY (with 27,532 people per square mile; 10,630/km²) apparently yes.. And the density of Dharavi slums in Mumbai India, with 770,000 people per square mile; 300,000/km², obviously in a small fraction of that.
Space for people is not the limiting issue … a whole heck of sparsely populated areas.
If cost is not a factor then we have the technology to produce enough energy including to run desal. Not cheaply enough that it is practical but that is not the question posed. Nuclear, widely used solar and wind, so on. Most of the world cannot afford it but we are talking the hypothetically possible not real world possible.
I can find estimates for maximum from currently arable land, if all foresake meat, to top off at enough to feed 10 billion, but there is a lot of land that could, using current technology, be made arable, mostly in Latin America and Sub-Sahara Africa (if we ignore the ecologic consequences) … realistically though that report considers a 5% increase by 2050 to be generous. But playing the question, packing people more densely can open up a whole mess of new arable land. How much? I haven’t the foggiest. Enough energy and we could, using current technology, do a heck of a lot of food growth with indoor multilevel farms and hydroponics. What would be the limit to that? How would you calculate? Again though the limiting factor is cost.
