The role of tropical forests in the global climate system must ultimately be evaluated using global models as the analysis tools. At present global models of the climate system specify the nature of the continental surface and parameterize its interaction with the atmosphere and hydrosphere. Currently the available global models exclude chemical and compositional changes caused in the process of deforestation. Despite these severe limitations, the sensitivity of such global climate models to prescribed changes thought to be reasonable representations of the impacts of deforestation can be evaluated.