It's also worth noting that "too difficult to harvest from an economic standpoint" is a moving target. If prices go up, oil which was not possible to extract profitably can become profitable. That means that "running out of oil" won't happen absent some crazy government intervention, since as supplies dwindle, prices will go up, and new oil will become profitable to produce.

This is worrying in terms of climate change because "difficult to harvest" usually means "energy-intensive to harvest." For example, tar sands require expending around 20-30% of their energy content to extract them in usable form, which means that CO2 emissions from burning that oil are effectively 20-30% higher.

If peak demand means we'll be able to leave the most difficult oil in the ground, that's excellent news.

>It's also worth noting that "too difficult to harvest from an economic standpoint" is a moving target.

Good note. Oil is fairly inelastic. I would say terminal velocity on that would be just before it costs the same amount of energy to extract energy. That can be converted to dollars just as well. That's a good thing about renewable and alternate energy, it erodes that inelasticity so when terminal velocity hits, we aren't all breeding horses again.