Science Forums 2

[CraigD]

Originally Posted by Little Bang

Let us suppose that we find an island that has just enough arable land to support one person for the rest of his life. We build a dome over the island that allows sunlight and is big enough to have clouds form for rain. Now suppose we introduce two men and three women. They will all be dead within six months.

I don’t believe we can say with certainty that all six of the people in this scenario would die. Possibly, some would die (eg: five), but some (eg: one) would live.

Originally Posted by Little Bang

Why is it so hard to understand there is no difference between the earth and that island?

It’s not hard, I think, but rather incorrect.

In addition to my previous objection, the analogy is very inexact, because the Earth has many times more than enough arable land to support its current population using current agricultural techniques. As noted here

Originally Posted by CraigD

Given current agricultural technology, it requires on average about 1/3 of an acre and 1 day to produce food with a nutritional value of 2000 kcal (about 2 kcal/m), about what one human requires each day. There’re about 21 billion acres (8.5 x 10 m) of productive land on Earth (sources: http://esa21.kennesaw.edu/activities...odcalories.pdf; The Population Press) - about 57% of its land area. So, roughly, with current agriculture and perfect management and distribution, no surpluses, and no bad luck, Earth can sustain a population of about 63 billion humans – a bit less than 10 times the current population.

This is not to say that overpopulation is not a serious concern, only that the human population-bearing capacity of Earth is not currently close to being exceeded.