Using possibility functions for long-term environmental planning

Current forecasting methodologies are deficient because they are only reliable for a few years into the future and focus on predicting the future. Serious environmental problems may require planning horizons in excess of 100 years. This article presents a planning method which uses possibility functions. Possibility functions that describe demographic variables can be combined with themselves and with probability functions that describe uncertainty about scientific knowledge. The article illustrates how possibility functions could be used to study the CO₂ problem.