The short answer is "yes." Oil is a finite resource, formed millions of years ago by the compression of billions of tons of animal and plant matter, which collected in pockets under the earth's surface. In the century or so in which oil has been exploited as an energy source, a great deal of the entire supply has already been extracted.
A phrase that is coming into the common vernacular is "peak oil." This is defined as both the peak amount of global oil production — that is, that oil is being extracted from the earth as fast as is physically possible — and the moment in time the amount has been reached. There is no debate that such a peak exists; the only argument is how far in the future we will reach it.
It is estimated that some 800 billion barrels of oil have already been extracted. Campbell and Laherr ère, of Petroconsultants in Geneva, estimate that there is perhaps some 1000 billion barrels remaining, and that the peak will be reached around 2010. Since most analysts acknowledge that the peak will only be recognized once it has passed, there is a growing number of analysts who suspect this point has already been reached.
Most of the major oil fields have been in production for decades. Matthew Simmons, one of the leading bankers to the industry, believes the huge fields in Saudi Arabia have already peaked; they have been in production for 30-50 years and are already using tertiary techniques to extract the oil. Tertiary techniques are the third level of oil extraction, after the easiest methods have stopped yielding, and are correspondingly more difficult and expensive.
Many people shrug off alarm about the pending energy crunch with a belief that "alternative fuels" will fill the gap left by receding oil supplies. This belief is overly sanguine, given the degree to which the entire industrial and technological infrastructure depends on fossil fuel. Converting to other fuels will be a massive financial undertaking to dwarf the military buildup of World War II.
Formerly third word nations are becoming more industrialized and as a result, global demand for oil is increasing. Since alternative fuels are not "in the pipeline," a drop in the supply would have an earth-shattering effect on the economy.
Some analysts even believe that the depletion of the oil supply will result in the downfall of technological civilization. But in any event, you can expect that the struggle to control the dwindling supply to spark conflicts between oil-starved nations and those nations whose territories contain still-producing fields. Energy wars on top of a global depression will siphon off even more funds that might conceivably be used to convert to alternate energy sources.
It is clear ideal time to invest in alternative fuels and energy-efficient transportation is well before the need for them becomes critical.