One of the most persistent worries about population and economic growth is that we will eventually use up all our resources and land. It is based on the intuitive (but false) assumption that if it takes X acreage of land to feed a person today, then it will take 2 times X acreage to feed double the population in the future. This thinking does not allow for ongoing innovation and adaptation.
Look at this graph showing total global hectares being used in farm production from 1960-2009. Note that the global population grew from 3 billion in 1960, to 6.8 billion in 2009.
(Source: Nature Rebounds)
The population will likely grow again by half over the next fifty years. Note that the projections are for the number of hectares used for farming to actually decline. The alternative projection assumes we adopt more efficient food consumption and stop growing crops for fuel. In either case, we will be using significantly less land than we did in 1960.
This is one example of decoupling, where two seemingly connected trends become disconnected. We are seeing this in water consumption, CO2 produced per dollar of produced goods, and with the amount of natural resources we use. The direst predictions about resources and climate tend to minimize or ignore these decoupling developments. We should not allow dire predictions that ignore decoupling to frighten us away from growth and achieving prosperity for the whole world.
Challenges? Yes. But we are not at the edge of doom.