What, then, is the natural amount of money required?

FORBES: Yes, Printing Money Can Create Wealth

As you all know, natural gas is -- a growing amount of natural gas, the reserves, because of the ability to frack shale rock, has been increasing.

WHITEHOUSE: Press Briefing

Although you went on to recognise that human activity causes these natural flows to become unbalanced, it can actually take only two or three decades for humans to cumulatively emit an amount that matches those natural fluxes, given how long carbon dioxide persists in the atmosphere and the low amount that the earth can absorb each year.

ECONOMIST: Letters