[Northstar (OP)]

The Earth is 2/3 or 3/4 salt water.  Yes, there are some fish which can sustain some people's need for food.   There are deserts and there are frozen areas and there are mountainous places on the planet.  And some few people can be sustained in each of those areas.   But it is obvious that humans must have regulations against overfishing.  Or the greed of the harvesters will cause the extinction of fishing grounds just like the passenger pigeon went extinct by people killing it for food.  Constantly, organizations ask for money to buy food for the poor, starving people living here or there instead of asking for condoms or for birth control pills or for education on family planning.   In fact, republicans in the USA are on a mission to de-fund planned parenthood and women's health.

The only alternative to neglect family planning and to determine how many people can live in any given area is for nature and the most base human nature to curtail overpopulation by nature causing the deaths of millions of humans by disasters, starvation, diseases, or by the most coarse of humans killing other humans such as in wars.

The Earth is a life raft afloat in space.   Yes, the Earth can sustain some life in growing areas as long as pollution can have dilution in the soil and in the waters.   But how many people can be sustained in the long term over farm lands versus the short terms of population growth and then, death by nature or other humans?

[alancalverd]

The British Isles and Japan are about the most intensively cultivated parts of the world, and could in principle sustain around one fifth of the present population indefinitely. Some tropical and mediterranean areas could in principle support maybe twice that population density but once you get above 2000 ft altitude or more than 100 miles from the sea, human life becomes a bit marginal, so overall I guess the world could sustain between 25 and 50% of the present population at present standards of living, and maybe 10 - 20% at a decent "western" standard.   

[David Cooper]

...but once you get above 2000 ft altitude or more than 100 miles from the sea, human life becomes a bit marginal...

Not sure about that - there's reasonably good agriculture at much higher altitudes than that in some parts of the world, so long as they have enough water, and very productive land hundreds of miles inland. Access to the sea certainly makes a huge difference though in any dry country though.

There are ways of making the planet sustain a large population well, and technology will make that easier over time. Solar power is becoming cheaper and more efficient at a pace, and it could be used for desalination (and to pump this water inland from the sea), thereby enabling extensive amounts of food to be grown in places which can't support many people at all today. We might find that the planet can support 50 billion people comfortably and sustainably, though quality of life could still be low if we kill off the diversity of habitat that makes life interesting and the empty spaces where people can get away from the crowds to maintain their sanity, so we need to preserve vast tracts of wilderness at the same time. 10 billion might be a very good population size, but if we can fit 20 in without spoiling quality of life significantly, it makes sense to allow twice as many people to enjoy existing in a given length of time. The rule is that we should play it safe, but not put unnecessarily low limits in place either. Another key consideration though is that we will have problems at some point such as supervolcano eruptions which could result in a decade of failed agriculture and another decade of slow recovery of production, so we need to store enough food to get everyone through such an event - that should be the main focus of mankind as we build a beautiful future, because we should be digging in here as a first step to make our future secure, and only then should we try to set up permanent bases on other planets and moons.

[wolfekeeper]

The British Isles and Japan are about the most intensively cultivated parts of the world, and could in principle sustain around one fifth of the present population indefinitely.

My understanding is that, without truly radical technology, the UK could just about support its population, but that it is a bit marginal; it could easily support half its population.

During WWII, when agriculture was far less advanced, but the population was only 47M it basically supported the UK population; but much land that was not normally considered agricultural was pressed into use with extra labour, but much of that lapsed again at the end of the war.

With far more radical technology in general, there is going to be a limit, but it's very, very high. You would do things like grow lamps and hydroponics. If you restrict yourself to solar and (perhaps) wind power it's higher than we are at at the moment, but if you include nuclear and beamed solar power, then the limit is only really a thermal one; we're ultimately limited only by energy.

[Northstar (OP)]

I think the replies are missing the point.
The point is that sooner or later, the number of people will reach a saturation point whether it is caused by lack of food, lack of water, lack of living space, lack of pollution dilution, lack of a good standard of living.

haiti is a good example.  Forests cut down for cooking which allows runoff of silt into ocean which wrecks fishing grounds which causes extreme poverty which causes exodus to the USA so that haitians can overpopulate the USA and cause the same problems.

The same goes for blacks and browns leaving africa for Europe and the UK.

[chiralSPO]

haiti is a good example.  Forests cut down for cooking which allows runoff of silt into ocean which wrecks fishing grounds which causes extreme poverty which causes exodus to the USA so that haitians can overpopulate the USA and cause the same problems.

The same goes for blacks and browns leaving africa for Europe and the UK.[/size]

...and the award for most blatant racism goes to... Northstar!

I think the replies are missing the point.
The point is that sooner or later, the number of people will reach a saturation point whether it is caused by lack of food, lack of water, lack of living space, lack of pollution dilution, lack of a good standard of living.

Yes. All of the resources available on the Earth are available in finite, fairly well defined/known, amounts. There is a LOT of energy that could be at our disposal, so this is likely not going to be a limiting factor. However, eventually we will need to be able to recycle all of the material required for civilization/economy etc. And it will take a considerable amount of energy to turn waste streams into useable products again. The amount of any resource available to the average person is largely determined by how many people there are. There is a whole spectrum of stable solutions, ranging from few (resource-)rich people, to many (resource-)poor people. The better our technology is, and the more energy we can take advantage of, the more resources will be effectively available for people. We just have to figure out what sort of life we want to have (and this is not something likely to be agreed on by everyone in the world!)

[Northstar (OP)]

chiral, do you deny that blacks and browns are leaving their overpopulated areas in africa and in the caribbean and heading for europe and the US?    If you don't deny that, are you a racist for pointing out or agreeing with such FACTS??

[chiralSPO]

I do not deny that people are moving from poor countries to rich countries, and there is probably a correlation to skin tone. My objections were to: (a) the notion that immigrants will bring all their problems with them, or somehow generate those problems where they end up; and (b) the implication that skin color has anything to do with the societal problems in 3rd world countries.

Of course there needs to be a mechanism by which immigrants are integrated into the societies of the countries they move to. Having refugee camps (officially or de facto) in wealthy countries is counter-productive. I believe that the social/political/economic systems in place in the wealthy countries are strong enough to accommodate an influx of poor and ill-educated people, and that 2nd and 3rd generation descendants of those immigrants are often very productive members whose contributions to their new homeland more than balance the "cost" of accommodating the 1st generation. I present as evidence 200 years of history of the US and UK, both of which have benefited dramatically (most obviously in the US) from this process.

[Northstar (OP)]

Let's go back to the original question:  For a given area, is there a population limit which the area can sustain.  That is whether it is by food, water, fuel, standard of living, crime or lack of crime, etc.

If blacks and browns have overpopulated their countries whether in africa, south and central america, the caribbean, American inner cities, asia, and IF they migrate to predominantly white countries like europe or the USA, will blacks and browns PREDOMINANTLY remain in impoverished conditions and with crime and low standards in education through overpopulation of their new locations?   The answer is YES.  The proof is in American cities.  The american inner cities are NO different than africa, the caribbean, central america, asia, etc.   And YES, it is a skin color problem such as with rap hate music, lawlessness, lack of respect for teachers and police and whites.

And why does there need to be a mechanism to integrate blacks into societies when they have FAILED to conform to white standards after literally hundreds of years?    I seriously doubt that the USA has benefited from hundreds of years and generations of blacks and browns even though, yes, there are some of them have done well in sports, police work, as teachers, medicine, etc.   But as a rule, the answer is NO, the country has not benefited from having blacks and browns in the USA due to a lack of discipline, lack of respect of others and laws, single family homes without strong fathers, lack of jobs and therefore lack of self respect.

[alancalverd]

There is little evidence that the few people currently leaving Africa have been driven out by overpopulation. The majority, like the East African Asians who left a generation ago, seem to be middle-class professionals and skilled workers who can afford to pay the smugglers to ship them out of a collapsing society.

As with all migrants and refugees, the cream and the scum are the first to leave: the difficulty for the receiving nation is to separate the cream from the scum, especially when, as in Iraq, the West doesn't know which side we are on. 

It would be difficult to pretend that the North American colonies did not benefit from slavery - why else would they have imported shiploads of Africans as manual labor? Or that the USA did not benefit from a steady stream of European intellectuals escaping various pogroms and revolutions in the 19th and 20th centuries.

Problems arise when any immigrant community either refuses or is refused to integrate with the hosts. As long as there is money in religion, and the state tolerates the teaching of superstition and protects evil disguised as faith, there still be intentionally disaffected muslim communities in the UK. Likewise "black culture" - a predominantly manufactured but very profitable product if ever I saw one.