SIMULATING CHANGES IN GLOBAL LAND-COVER AS AFFECTED BY ECONOMIC AND CLIMATIC FACTORS

This paper describes two global models: (1) an Agricultural Demand Model which is used to compute the consumption and demand for commodities that define land use in 13 world regions; and, (2) a Land Cover Model, which simulates changes in land cover on a global terrestrial grid (0.5(0) latitude by 0.5(0) longitude) resulting from economic and climatic factors. Both are part of the IMAGE 2.0 model of global climate change. The models have been calibrated and tested with regional data from 1970-1990. The Agricultural Demand Model can approximate the observed trend in commodity consumption and the Land Cover Model simulates the total amount of land converted within 13 world regions during this period. Some degree of the spatial variability of deforestation has also been captured by the simulation. Applying the model to a ''Conventional Wisdom'' scenario showed that future trends of land conversions could be strikingly different on different continents even though a consistent scenario (IS92a from the IPCC) was used for assumptions about economic growth and population. Sensitivity analysis indicated that future land cover patterns are especially sensitive to assumed technological improvements in crop yield and computed changes in agricultural demand.