Earth is room enough

A while ago, on a plane to the UK, I was wondering just how much land there is per person on the planet Earth. The Earth's surface area is about 5500 trillion square feet, but only 30% of that is land, and of the land only 30% has farmable topsoil (the rest is snow, mountains or desert) hence approximately 10% of the Earth's surface is farmable land. So by my calculations, if the Earth's seven billion inhabitants all spread out evenly across that land we'd each have about 78,600 square feet to call our own^*. That is a square about 93 yards on each side, or 1.8 acres, or around-about a US city block.

Not exactly roomy, but then you should allow for a reasonable amount of cohabitation of plots via vertical development and simple sharing due to the existance of families. Also there is bound to be some spreading out into some of the 90% non-farmable areas - it might be an idea to keep the farmable area for farming. All things considered it is clear there is going to be a lot more land available per family, probably five to ten acres. But the question is, just how much land does each person need to keep themselves feed and watered?

Another way to think of these figures is to compare them to a city dweller living alone in a two bedroom apartment of 700 square feet. Effectively they using 1% of the land that is theoretically available and that's without considering vertical stacking of apartments in a city. Its likely most industrialized cities have a density of people that is ten to one hundred times higher than single storey developments would yield. Thus you city dwellers are probably using one-thousandth or less of the land available. Since the majority of the worlds inhabitants now live in cities its clear there is still a lot of room out there.

Of course I'm not condoning over population, just trying to get some sense of perspective. What would be nice of course, was if the majority, if not all of the current seven billion people were actually out of poverty, able to get critical health-care, education, enough food to eat and clean water to drink. For well over a billion even getting a simple light after dark is a big problem of the day.

^*Yes I know these calculations don't leave any room for farmable land that is used by parks, wilderness, uninhabited or for infrastructure. If you want divide my final figures by two.