Emissions of carbon dioxide predicted from the unconstrained parabolic projection of world conventional resources of oil and natural gas were plotted in these two graphs. Conventional output from these two fossil fuels is determined more by the rate of discovery than any other factor in view of the ample economic driving force arising from their generally low technical cost of production. Production of non– conventional oil and natural gas, whether oil derived from the oil sands, natural gas from coal beds, or from conventional operations in harsh or ultra-deep environments is similar to the situation applying to coal in that output is generally limited by the deployment of the necessary facilities. These are two quite different production mechanisms and it is important to distinguish between them. It is of interest therefore to estimate the quantity of carbon dioxide likely to be produced from conventional oil and natural gas counted together in an unconstrained 'business-as-usual' situation free of policy intervention.

Two separate calculations were made of the total emissions of carbon dioxide to be expected from the world conventional resources of these two fuels. In the unitary case where the world resources of natural gas were considered as a single unit, total emissions of carbon dioxide from oil and natural gas together peak in the range of 5093 and 5192 tonnes of contained carbon per year. In the segregated case, where North American gas production was considered separately from that of the Rest-of-the-World, the emissions of this gas peak between 5048 and 5119 million tonnes of carbon per year. The timing of the high and low total peaks was found to range over only eight years from 2021 and 2029 in the unitary case and six years from 2020 and 2026 in the segregated case.