Source: Adapted from an example displayed on Wikipedia. http://en.wikipedia.org/wiki/Export_Land_Model
- Production. Assuming a continuous and linear decline of production is unrealistic because as production declines, prices and efforts made at finding new reserves would accelerate. This would mitigate the production decline process over a longer period of time. Additionally, global business cycles have an impact on production.
- Consumption. The assumption that consumption (demand) steadily increases is also invalid. For a variety of reasons, namely business cycles (growth and recession), technological innovation (more efficient use), substitution (usage of other sources of energy) or even demographics (population stabilization and decline), demand could easily remain constant, increase at a much lower rate, or even decline. For instance, many oil exporting countries are subsidizing fuel prices for their populations, which leads to waste and over consumption. If with a decline in revenue generating exports, an oil-exporting country decides to remove some of these subsidies and let the national population pay market prices, it can then be expected that national consumption could level and even decline.
- Exports. Because of the variations noted on production and consumption, exports are likely not to decline in a linear fashion and may actually increase if national consumption declines.