I've qualified for a (relatively) steep loan from the credit union. As a couple, our credit score is rather low. I tried to get the loan just on my credit, but things are the way the are. The loan officer pretty much told me that at the level we're at, it's up to her discretionary powers to judege whether I'm a good risk. We've just used up all our principal.
As a species, we've borrowed against the planet's principal so heavily. Loss of our principal in terms of shrinking aquifers and marshes, the ocean's ability to cleanse our wastes, and the loss of arable land is increasing our "debt"... and there's no parallel entity to the G8 in Mother Nature to "forgive" our loan. We'll pay the price.
Gil Friend writes that we have to rebuild the plane in mid-flight.
So here I am, one little bit of the fractal creature that is Humanity, with my past choices forcing the current options to be a little more expensive than I'd like. By choosing to get away from over-consumption, however, I'm paying off my past debts while creating a small (and growing!) space to pay back into the principal.
When I build up the principal enough, I can live off the interest again. As a species, we have to undestand this: we can't use the principal to live off of. We have to discover how to invest in natural resources so we can live off the planet's interest.