Sounds kind of like how we're running out of oil -- we're definitely using up the easy to find deposits, but as oil prices rise, the less easily available oil b

Sounds kind of like how we're running out of oil -- we're definitely using up the easy to find deposits, but as oil prices rise, the less easily available oil becomes marketable, so the oil keeps coming. Eventually we'll run out, but making it harder to find just makes it more expensive. (well, that and the political problems caused by wealthy middle eastern nations running out of their liquid gold)