MODELING SUSTAINABLE DEVELOPMENT

Some of the difficulties of extending economic and ecosystem models to allow for long term forecasting applications to the problem of sustai nable development are discussed. It is argued that the new generation of models required will be nested models with fine time-space grid sub -models of non-global smaller scale phenomena imbedded in global scale coarser grid models. These models will have to be constructed by addi ng the economic dimension to the already interdisciplinary ecosystem m odels and will require the introduction of an economic numeraire which is invariant and compatible with common units of the other discipline s.