AbstractThe world models put forward by Jay Forrester (‘World Dynamics’, 1971), and by Dennis Meadows et al (‘Limits to Growth’, 1972) can be modified to yield striking results. In both the models, the interdependence of the factors involved means that slightly different assumptions can change the conclusions significantly.Johan W Brinck, of International Resources Consultants (IRC), in the Netherlands, in an article inEurospectra(XIII, 2) demonstrated the use of the modified model, and extracts from his article are given below.