I have written extensively on the subject of Peak Oil as indeed have many others. This is not surprising perhaps in view of its significance, and the almost certain consequences of ignoring its eventuality, which some think will be the collapse of civilization as we know it. The worst case is the "Die-Off" prognosis, in which around half the world's population of 6.5 billion will be consumed through wars over resources and by starvation. This is unlikely to be an evenly proportional loss of life, as is indicated by the relative population increases across the world. For example, in the UK in 1900, the population was close to 40 million, and now it is 60 million. As a world total it was around 2 billion, and so there has been an overall more than tripling in numbers, mostly in the developing world. Hence, without a plan, it is there that the greatest losses will be suffered.
The growth in human population can be plotted on the same curve as that for the rise in oil production, and that is not surprising given that we depend on oil or gas (which are interrelated in their production) not only for fuel to drive transportation and to provide much space-heating too, but also as a chemical feedstock for industry, and there is practically nothing we use that does not depend on hydrocarbons in some way, including food. Even "natural materials" like wood are treated with chemical preservatives. At one time the main wood preservative was creosote, and made from coal tar, now it is a mixture of more exotic substances sythesised ultimately from oil. If we are close to the peak in conventional world oil production, beyond which it is thought the amount of oil recovered will begin to drop at a rate of 2 - 3% per year, then what? Is a Die-Off scenario leading to a post-apocalyptic Mad Max outcome inevitable?
I don't believe it is, but exactly what happens depends acutely on what we choose to do about the impending oil-crisis, now. There are many who think that this is just another scare because we have seen "oil-crises" before, notably in the early 1970's, when the OPEC cartel flexed its political muscles to drive up the price of crude oil. But it was merely a political matter - there was still plenty of oil in the ground to be recovered and OPEC could decide how far to open the valves from the wells of its giant fields. Now the constraints are not political but geological, and it will simply become impossible to pump enough oil out of the ground to match an inexorable thirst for it. Indeed, production of the "sweet" (low sulphur) light crude oil which is most readily refined into gasoline (petrol) and aviation fuel has already peaked, and henceforth we will rely increasingly on processing heavier kinds of oil and that produced by thermally cracking tar sands and shales which are all highly energy-intensive processes, and the latter especially demanding additionally in the resource of water required to run them.
Future historians may well record that it was a pity humankind did not act 30 years before the peak, probably when OPEC temporarily throttled-back its output of oil. There were many research projects inaugurated to find alternatives to oil, but they did not become large-scale enterprises, because cheap crude oil came back onto the market and quenched the incentive for them. Now the incentive is paramount. For example, food production depends on oil to run farm machinery etc., and on natural gas to manufacture chemical fertilisers to squeeze greater crop-yields from land that has become extremely depleted in organic matter. If we lack oil, we have no choice but to return to organic farming, ploughing manure from animals back into the ground to nourish the next year's harvest. Organic farming requires far more land to yield a given quantity of crop than chemically-driven modern intensive farming methods do, and so to keep a nation fed, there is little arable land left on which to grow crops for biofuels. New cellulose-fermenting technologies that turn waste into fuel then look increasingly attractive, but we need them on-line as soon as possible, not forgetting that all our implementations of alternative technologies must be done within about 10 years, by when oil supplies will have begun to fall significantly, and against a demand for oil that grows by around 3% each year.
Transportation is THE big problem. I retain considerable optimism that cellulose-based methods will prove useful and I like the idea of making biodiesel from algae, although that technology too has many problems that need to be ironed-out before it might be possible to do so. Implementing a "Hydrogen Economy" on the scale required to substitute for oil-driven (forgive the pun) transportation would demand a feat of engineering so great that it is probably prohibitive, as I have indicated in previous postings and so I think that given the limited time left to us, we would be better to seek our salvation elsewhere. There seems no doubt that we will be forced to curb transportation (especially personal transportation) considerably, perhaps by 80 - 90% within 15 years, and that inevitably means a considerable relocalisation of society into relatively small communities, supplied by local farms. If that sounds like a slide-back to the Stone Age, it is probably worth recalling that this is exactly how Cuba managed not only to survive the abrupt loss of oil and chemical fertilisers from Russia when the Soviet Union collapsed, but to become a thriving nation based on local-economics. In Cuba, local farms provide for local markets, and while there are still some food shortages in more populous places like the capital Havana, as an overall strategy it has worked.
We must plan now, rather than remaining in denial that the onward march of progress is at all possible. The future can be an optimistic one, if we choose the simpler way. We will have this ultimately, whether we choose it or not, since it is the "default-setting" for a society with less energy at its disposal. That said, it is in our hands just how rough the transition is from now to then.