The Earth's population limit

Question

As the world continues to increase in population, what is considered to be the limit in terms of amount of habitable living space and resources?

A couple of assumptions:

• Famines are not (or very rarely) caused by wars, terrorism, dictatorships, corrupt governments, corporate exploitation, etc.

• Resources can be distributed quite easily.

• Problems using land for living space and resources that arise from simply not having the technology, or political/economic will have been overcome.

What I'm trying to figure out is what the limit is before actually moving some of the population to another planet becomes a desirable alternative, but assuming that by the time we have the technology to do that, we also have the technology to resolve our resource issues.

Answer 1

"moving some of the population to another planet" is never, except under very interesting (technological) circumstances, going to be a feasible alternative.

Remember that it takes a pretty large amount of energy to get payloads into orbit - especially squishy payloads - never mind to another habitable world.

If a civilization had that kind of technology, and such an abundance of resources they probably wouldn't have gotten into a situation where they've overpopulated a world to begin with.

Instead, what would most likely happen is that those with the means to get off the world will do so, while those left behind will slowly give in to panic and despair, fight over the scraps of food left on their crippled world, and eventually die en masse.

If you choose to disregard such basic aspects of economics (which is what it comes down to) and historical examples then the population limit doesn't really matter anymore, because you're making it all up anyway.

Our planet already holds 7 billion human beings, and consumerism is still alive and well, so I can only imagine that we could sustain another few billion until we end up slaughtering one another for food and water (iPhones will be a long forgotten luxury by then).

Answer 2

There are currently over 7 Billion humans inhabiting the Earth and that value is increasing exponentially, its estimated that by the end of the century the human population will reach numbers of over 10 billion but scientists are unsure if even this is sustainable.

Lets start with food; If you were to take all the land area being used for modern livestock and put it in one place, it would take up all of Africa (7.5 billion Acres), in fact even Africa would not be large enough as it would require 8-9 billion acres. Doing the same for crop production would take up an area the size of South America (4.4 billion Acres) but after a while the soil in these areas will degrade until fertility decreases and it erodes, rendering it useless for growing crops and not only that but scientists are unsure if farmers can even maintain their current cop yields due to changes in the environment.

See, the global average of carbon dioxide emissions per person is about 5 metric tons per year but for Americans that averages closer to 17 metric tons per year. Remember this is per person so if we have about 3 billion more people living on this planet and they all adopt a life style similar to an American, the effects of global warming will be worsened even more, in fact it's projected that the temperature of the Earth will increase by 2 degrees Celsius by the end of the 21st century and with that increase comes more extreme weather conditions which would inevitably disrupt food production even more. This can be partially remedied by forcing a everyone on Earth into a purely vegetarian diet and reclaiming the land to grow more crops instead of raising livestock but the crops won't be enough to feed an infinite number of people in fact some scientists predicted 10 billion people and more than likely most people will not voluntarily switch to a vegetation diet. After all, bacon is a beautiful thing.

But what about the available water? Humans are currently using up to 30% of Earth's accessible water supply with the rest being used for agriculture and the water available to some people in countries life Ethiopia, Cambodia and Haiti isn't even clean enough to drink. So the amount reaching humans would have to increase with the increasing population so to answer the original question, Earth may be able to hold up to 10 billion people living decent lives and may be able to hold more, but the quality of those people's lives (past the 10 billion mark) would be much lower than they are right now.