jay gw said:
Which part why? Why will it peak, or why will it decline slowly?
I think it will peak because, as far as we know, it is not a renewable resource, and the supply (though very large) does appear to be finite. It would be great if that's not the case, but I wouldn't count on it. On the flip side, of course, I wouldn't be willing to bet anyone on WHEN the peak will happen. For all I know, it might not peak for another hundred years or more.
As to the extended tail, well, there's a lot of oil out there that's hard to get at. At current prices and with current technology, this oil is to expensive to obtain and is therefore not accessible right now. If oil production peaks, then that's pretty much guaranteed to start pushing up oil prices. As prices rise, successively more of these reserves will become accessible. So any decline in production is likely to be slowed due to the successive exploitation of more difficult-to-obtain reserves. That process could possibly drag out for a very long time.
The problem, though, is that even a leveling off of the oil output is going to cause problems: the world works fairly well on a global economy that's growing at a pretty fast rate, which in turn depends on a growing energy supply. If the energy supply saturates, then economic growth is limited to efficiency improvements, which are fairly slow. Nobody is quite sure how the global economy will work in a low-growth environment, but the potential for increased global instability is there. I'm not talking doomsday stuff, just a generally higher level of violence and strife. We would therefore like to be able to keep the growth of energy supply going, but that may not be possible, or maybe not at the rates we've seen over the last half century.