Standing room only?

Since time immemorial, people have thought the world to be over populated, as can be illustrated from these two ancient snippets:
"There was a time when the countless tribes of men, though wide dispersed, oppressed the surface of the deep-bosomed earth, and Zeus saw it and had pity and in his wise heart resolved to relieve the all-nurturing earth of men by causing the great struggle of the Ilian war, that the load of death might empty the world." - Cypria or Kypria, 7th or 8th century BCE. (estimated world population 75 million)

"What most frequently meets our view (and occasions complaint), is our teeming population: our numbers are burdensome to the world, which can hardly supply us from its natural elements; our wants grow more and more keen, and our complaints more bitter in all mouths, whilst Nature fails in affording us her usual sustenance. In very deed, pestilence, and famine, and wars, and earthquakes have to be regarded as a remedy for nations, as the means of pruning the luxuriance of the human race;" - Tertullian, Treatise on the Soul, 2nd or 3rd century CE. (estimated world population between 200 and 300 million)

I tend to disagree.

Just for fun, I pulled up numbers on population density in various cities around the world. And then I calculated how much area would be required to house the world's population (I used 6,500,000,000) at a similar density - effectively a mega city.

CityPopulation Density (persons per Km2)Equivalent area to house world population (Km2)
New York10,456621,652
Washington D.C.9015721,020
Portland, Oregon41991,547,987
Hong Kong63521,023,299

The Earth has an estimated land surface area of 148,939,100 Km2 or two orders of magnitude more area than required to support the current world population at densities equal to that in Montreal (I assure you that Montreal has plenty of green space and trees).

In other words, a mega city as densely populated as Montreal would occupy 1% of the world's land surface. At population densities of Paris or Manhattan, such a mega city would occupy less than 0.2% of the world's land surface.

If we lived in a mega city with a population density equal to Toronto, the entire world's population would fit in Indonesia.

If we lived at densities found in New York City or London, the world population could squeeze into France.

If we wanted to live at densities found in Paris or Manhattan, the world population could comfortable fit in Colorado or the United Kingdom (if you included Ireland, my apologies to the Irish who consider themselves separate).

The rest of the world would be empty. There would be no people.

At such densities, can you imagine the reduction in pollution, the savings in energy? Economies of scale would be fantastic. I have a house in Montreal. It is a modest home sitting on 6000 sq. ft (600 m2) of land.

If such a mega city was organized as a circle and the population density was similar to Montreal, it would have a diameter of 1366 Km. If you lived in the centre of the city, it would be a maximum of 683 Km to any point. Taking a bullet train, you could reach any point in less than 3hrs (assuming a direct run).

I would assume public transit would be very good and cars would be almost non-existant, since there would be no need for them.

Scientists (and people) tend get excited with exponential growth curves. However, exponential growth curves never are, they tend to be S curves - there is slow initial growth, followed by rapid expansion, followed by slowed growth.

Thoughts to think.

Population and land stats taken from Wikipedia (I also could have used the CIA World Fact Book - which is a fantastic resource). I used Wikipedia because it already did the population density calculations for me.

Of course, housing people is only one part of it. Feeding them is another. I cannot find consistant information on land required for food production to sustain one person (quelle surprise as people pull out numbers to support their own agendas). I have come up with a range from 0.2 hectares per person to 1.2 acres per person. This works out to between 2000 m2 and 4856 m2 per person.

Which works out to requiring between 13,000,609 Km2 and 31,565,480 Km2 for agricultural land. Or somewhere between 9% and 22% of the world's land surface. Not sure if seafood fits into these figures or not (and fishing practices are horribly wasteful since by-catch - the fish caught but not wanted - is most often discarded. Greenpeace says that as much as 90% of a catch is by-catch. And we wonder why fish populations are dwindling when we discard a huge percentage of catch because it is unwanted).

You can get stats on country agriculture and food production from here. The site lets you browse once or twice before asking you to register.

Love the way the Earth's land area is given down to 100 Km2. Maybe we really do have such accurate measurements. I didn't bother rounding my numbers, except to eliminate decimal points, so they may indicate more precision than is warranted.

Image nabbed from here.

[Update 14-December-2007 @ 22:37 - change title from Is it crowded in here?]


KayMac said…
very interesting and thought provoking
Barbara said…
When I fly over this country and see just how much empty space there is, I have a hard time getting too worried about the population. I'm sure this is naive because much of that land is not habitable, but it still counts toward surface area.
Richard said…
kaymac: I think it is. My friends have gotten tired of me pulling out number like this. People need to put numbers in perspective.

Absolute numbers like China and India's billion plus populations are staggering, especially when you consider the population of England is only 51 million or that the Netherlands (Holland) has a population of 16.5 million.

Yet, when we look at population density (all in persons per square kilometre), we see China with 140 and India with a mind numbing 329. Yet, if we contrast this against "nice", "clean", "progressive", "modern" countries like England (388) and the Netherlands (395) we see that China and India suddenly don't look so crowded - especially not China.

Of course, in contrast to Canada (3.2), Australia (2.6) and the U.S. (31), those countries seem terribly crowded.

Canada, Australia and the U.S. are exceptions and exceptional in their abundance and wealth. The fact that they are also predominantly white and English speaking gives some credence to the argument that white and English is superior to all others. I think this is wrong and we have simply benefited from a happy accident of circumstance.

The general rule is that population density drives economic prosperity. In Africa, the chief problem (aside from their constant warring, fighting and bad politics) is lack of population, not over population: Ethiopia (70), Eritrea (37), Côte d’Ivoire (56) and Sudan (14). Ethiopia was known as the bread basket of Africa, but war (not drought) has impaired its ability to grow crops.

barbara: true, not all the land is habitable, but a lot of land is or could be made habitable. It is simply that we are wasteful in our use of it and our resources.

However, what do you define as habitable? I've been to Colorado in the Summer, and I can tell you that outside of Denver, it is oppressively hot and humid - I would not consider that habitable.

I am not sure I would be willing to put the geography around Salt Lake City as hospitable, or Lima (Peru), or Ica (Peru) since these are all desert areas.

Of course, living on the rockies might be problematic (yet the Andeans manage to live and farm on the mountains).

It was just an exercise in alternate perspectives.
b said…
Your argument is truly sound and indeed thought provoking. It no doubt puts a very compelling perspective on the notion of an overpopulated world.

Of course, the mega city is feasible but the thought of being confined to one climate, to one landscape is miserable to me. And I think people would rebel and seek out new land and lifestyle, just as we did centuries ago. Surely, that wasn't the point of your post, but it immediately came to mind! You know how easily I can spin off a subject! :)
Richard said…
breal: none of the information presented is new or hard to find. It just requires someone to question the information they are presented. Something I do constantly and it annoys people around me. "Why can't you ever accept anything I tell you without questioning it?" is a common refrain directed toward me.

When I was doing the breast cancer / pill thing a while back. Numbers (assuming I could find them) were not adding up either. One stat I came across frequently was that 1 in 9 women will develop breast cancer. Based on the epidemiological numbers I could find, I estimated it to be more in the 1 in 11 to 1 in 17 range. The only way I could get to 1 in 9 was to assume women were living to be somewhere between 100 and 120 years old.

As for the mega city ... well, I was not suggesting we actually live in such a mega city, but it served as a way to put population densities in perspective. I tried to pick cities people are familiar with (regular visitors), have probably visited, lived in, or consider desirable to live in.

I included data on land required for food production just in case someone complained I did not consider that footprint (and the fact that consistent data on agricultural requirements vary so much, seems to indicate that we really don't know the answer. Or

There is also the whole issue of ecological footprint. There is no question that if everybody lived like North Americans, sustainability would be a problem. On the other hand, increasing population density decreases the size of the ecological footprint we have.

I think a city with a diameter of 1400 Km would have a good climate variation. Or it could be divided into multiple smaller cities.
b said…
I know you weren't idealizing such a mega city but that came to mind as I read it. And again, very compelling evidence that I've never seen presented in such a way for that argument.
ingrid said…
It isn't just a "space for people" issue. It is a resource and feeding people issue. A lot of a land is simply not suitable for agriculture or for that matter, housing people.

The Netherlands is easy: its completely flat with absolutely no topography other than in the south. This is quite different in china and india.

There is a question of uncontrolled growth and is bigger better?

I think that sustainability is precisely the issue. As are issues such as landfill, water resources, arable land being taken over by cities (most of Canada's best farm land used to be within 50 km of Toronto and is now gone.) It isn't simply an issue of land area. It is much more complex than that.
Richard said…
breal: thanks

ingrid: should I even dare to debate you? I know you are far more the expert in this than I, however ...

Yes, I am aware there is a lot more than simply accommodation, which is why I included stats on land required for agriculture (according to the Wikipedia entry on China, it has 10% of the world's arable land at 5,000,000 sq. Km. Pegging total global arable land at about 50,000,000 sq. Km).

I did not consider waste management. But I chose cities for the express purpose of implicitly illustrating that waste management does happen at these population densities. Granted, there are technical issues beyond just running a few extra Kms of sewer pipes in such a mega city.

We in the West are quite profligate in our use and abuse of resources (especially so on this side of the Atlantic), which is why I threw in that bit about by-catch (again indirect hinting).

I have no idea what the definition of arable land is. I also suspect that more land is arable than is officially claimed. The Andeans seem to manage quite well in mountainous terrain, growing crops on steppes - granted it is very labour intensive and does not lend itself well to mechanization.

Finally, I never believe anything anyone tells me.

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