Okay, a few points.
We could fit the world population in Texas, maybe, but how would you provide for their needs? It's difficult to position population centers far away from a reasonably stable source of water. In fact, many metropolitan areas around the world have exhausted available local groundwater supply and draw their resources from distant aquifers.
Simply put, you can't position dense populations in wide arid expanses of land and keep the
cost of living down. Poor people have to live near
cheap potable water.
And since water and waste requirements mandate that companies position a lot of their factories along rivers... often near population centers, unpolluted ground water that is
easy to get to is scarce.
We don't need that much space, yes... you can crowd people in... New York and Tokyo are really swell examples. Well... how many people can actually
afford to live in New York? Not everyone makes US and Japanese wages. Australia is currently being hard hit by high urban real estate prices, rendering a lot of middle-incomers homeless.
Your average office worker in any third world country can't even afford a house in the 'burbs... and living space in any third world country costs a fraction of what it does in the US.
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Farmland is scarce in many countries. A lot of topsoil is washed away by wind and rain. Many farmers don't practice proper crop rotation meant to rejuvenate the soil. But if we're picking nits, heck, yes, there's a lot of farmland available... we just have to chop down all the forests that governments and environmentalists don't want us to touch, because they fix atmospheric carbon and provide us a reserve of biodiversity that is now rapidly dwindling. Plus, a lot of countries have stopped chopping down forests willy-nilly, recognizing them as a slow-replenishing resource. They need to maintain or increase the current amount of forest cover in order to be able to "farm" the trees effectively.
American farmers receive a big subsidy from the government so they can use expensive farming equipment and chemicals while still undercutting crop prices of farmers in third world countries, who can produce the crops cheaper because they don't spend a ton of money on them.
Same goes for Japanese farmers, actually...
It's actually very difficult for farmers in many countries who do have enough land to make a living nowadays, because the rate of trade and the price of their farm goods don't really cut it in the face of such cheap products from bigger countries and farms. That's contributing to overcrowding and poverty in urban centers, because your basic beggar eats better and makes more money than the average third-world farmer, even if he doesn't contribute positively to the economy.
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We aren't running out of physical space, but we're approaching the point where we can't viably maintain the current level of industry and quality of life that the small percentage of the population who can afford a decent house, a car and quick internet enjoy.
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Poverty: AIDS doesn't curb populations. It just gives you more sick people to think about. Look at Africa. I don't see poverty and population pressure easing, even decades after AIDS first came out... I just see millions of sick people. AIDS is painful and slow, slow enough that people with AIDS can still have kids before they go.
Now Bird Flu... that'll kill us all off.
