Jeff:

without addressing the problem of growth itself we'll just reset the population at some lower level, then grow again in excess of carrying capacity, and crash again, ad infinitum.

kenny:

But I haven't seen any alternative scenarios either.

Greer's Catabolic Collapse is one alternative model, that plays out much as Jeff describes above. In his the comment section of his most recent post on his Archdruid Report blog, he discusses the idea that the current financial thrashing is an example of the model in that area.

It'd be interesting, but beyond what I have the time or knowledge to take on, to try to apply his 4-factor model to the recent credit bubble and its collapse. Anyone here have good tools and expertise in system dynamics?

Greer's an interesting person. And of course he's a winner of the prestigious Order of Bards Ovates and Druids Mount Haemus Award for Druid scholarship...

I like the piece on Catabolic collapse, but it doesn't seem to be much more than a restatement of the ideas behind the World3 system dynamics model discussed in Limits to Growth.