1. The original analogy makes no sense unless there was a stable entity called “The Roman Empire” that existed for a while then suddenly (whether “suddenly” means over a year or over a century) disappeared. That’s something that historians in Britain worried about a lot during the 18th and 19th centuries, thinking about their own empire, but I don’t think it would stand up to modern examination (then again, I’m not an historian).

2. Whether or not the Roman Empire did experience a wood shortage, it makes no sense to compare it to the idea of “peak oil”, because, unlike with oil, Europe would once again (during the middle ages) have not only more wood than it needed, but more wood in absolute terms. Once we pass peak oil production, we may have enough oil for our needs (assuming we are using alternate energy sources), but we’ll never again have more oil in absolute terms within the life of our species. In other words, it’s a lousy analogy.

Given that “peak foo” is not the end of supply of a commodity, rather than the point and which the rate of production stops increasing and starts to decrease, you would expect it to start having an incremental impact over time. Rather than the Romans going to pieces as soon as they received a smaller shipment wood to Rome one day, the Empire started slowly winding down.

The problem with the reforesting argument is, as has been pointed out, one of time. I’d also be curious to know whether the significance of the supply of wood occurred to the Romans, or if they even realized that it might actually be in limited supply and hence worth planting and regrowing at all. Let alone whether they would have the knowledge and skills to actually do it.

Also, it’s clear the phrase “Roman Empire finally collapsed” was just a convenient way to briefly frame the speech in its introduction, so I’m not sure why you’re picking on that.

Imagine for the moment that peak oil hit today. What would happen to existing nations? Not much immediately, but you can bet that as soon as supplies began to have a visible impact, we’ll see the start of some fairly far-reaching changes.

/Mike