Peak oil is the point in time when the maximum rate of global petroleum prouction is reached, after which the rate of production enters terminal decline. If global consumption is not mitigated before the peak, a world energy crisis may develop because the availability of conventional oil will drop and prices will rise, perhaps dramatically. M. King Hubbert first used the theory in 1956 to accurately predict that United States oil production would peak between 1965 and 1970. His logistic model, now called Hubbert peak theory, has since been used to predict the peak petroleum production of many other countries, and has also proved useful in other limited-resource production-domains. According to the Hubbert model, the production rate of a limited resource will follow a roughly symmetrical bell-shaped curve based on the limits of exploitability and market pressures.