The PAGE ModelPAGE (Policy Analysis for the Greenhouse Effect) was developed with European Union support, in a parallel effort to ESCAPE. In contrast with ESCAPE, PAGE focuses on simplicity and ease of use, and allows extensive specification and propagation of uncertainty.
PAGE models the same four world regions as ESCAPE and represents emissions of CO2, CH4, CFCs, and HCFCs from 1990 to 2100. Emission projections are not modeled but are specified by the user. The model then generates emission-reduction costs from a set of regional no-cost emission paths for each gas, and marginal costs and break-points for a piecewise linear abatement cost function.
Emissions drive an atmospheric model that represents atmospheric lives of each gas and resultant time-paths of radiative forcing and global-average temperature. Impacts are assumed to be zero if the time-path of future temperature lies below a specified trapezoidal curve defined by an initial limit on the rate of temperature increase on total temperature change. If the temperature path passes above this region, sector- and region-specific costs are defined proportional to the excess. In all illustrative runs presented so far, though, the parameters of this time-path of "tolerable" temperature change have been fixed at zero so that costly impacts begin with any temperature change.
The richest part of the PAGE model is its treatment of uncertainty. All major parameters on the emissions, atmospheric, and impacts side are represented by triangular probability distributions whose parameters can be set by the user, and uncertainty is propagated throughout the model. No other distribution forms than triangular are available, however (Hope 1992 and Hope, Anderson, and Wenman 1993.
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The next section is The CSERGE Model.