"One day we will run out of oil, it is not today or tomorrow, but one day we will run out of oil and we have to leave oil before oil leaves us, and we have to prepare ourselves for that day," Dr Birol said. "The earlier we start, the better, because all of our economic and social system is based on oil, so to change from that will take a lot of time and a lot of money and we should take this issue very seriously," he said.The critical point is that it is a finite resource and once all of the easy to extract oil is gone, it becomes more expensive to produce right when demand is at its highest and production can not rise to meet the demand. So supply falls, demand is high, prices go thru the roof.
We saw the effect a year ago when gas prices tickled $4. Will they get there again any time soon? I have no idea. The point is that our dependency makes every aspect of civilized society and economies as we know them, extremely fragile. Prices can jump via market forces as mentioned above, shenanigans from OPEC, or rampant or predatory speculation (as many suggest caused last year's spike). Any or all of which can sieze up our economy and way of life like sugar in a gas tank.
Once again, I feel the need to quote Lewis Mumford with regards to the point of transportation and the underlying message that should percolate through all transportation planning decisions:
"The purpose of transportation is to bring people and goods to places where they are needed, and to concentrate the greatest variety of goods and people within that limited area, in order to widen the possibility of choice without making it necessary to travel. A good transportation system minimizes unnecessary transportation; and in any event, it offers change of speed and mode to fit a diversity of human purposes."