"Peak Oil" describes the point in history when the maximum possible amount of oil is being produced. Peak oil can refer to an individual oil field, an oil producing country, or world production. (For an animated map illustrating this situation, click here.)

The peak of production typically occurs when about one half of the ultimately recoverable oil has been produced. It is not a precise relationship; different methods of extraction will have an effect on the rise and fall of production. But everyone agrees that oilfields experience this rise and then fall in the amount of oil they can produce each day.

In North America, the peak year of production of conventional oil occurred in the early 1970s. In fact, most oil-producing regions in the world have already reached their peak production and are now in decline. The only major oil-producing region which may not be in decline is the Middle East. One of the challenges in assessing the nearness of peak oil is that there is very little reliable data from countries such as Saudi Arabia on their oil reserves. It is quite possible they are very close to their peak of production, which would mean the world has peaked.

Thus there are some people who say we have already reached the peak of worldwide oil production. Others say it is decades away. But even with the most optimistic projections, the work needed to reduce our dependence on the increasingly expensive, scarce oil will take decades - which is why we have to start now.