2. Population and Income as Drivers of Global Change

This chapter begins by reviewing the historical relationship between population and cropland expansion. It also considers the role of per capita income growth in shaping land use—particularly land devoted to non-agricultural uses, including forests, over the historical record. We then turn to the consideration of population as a determinant of future land use reviewing the basic concepts in demography, including the demographic transition, as well as a summary of the latest population projections to 2050. We also consider the interplay between population growth and current differences in consumption patterns across regions. Many of these differences are driven by per capita incomes. As population growth slows down relative to historical growth rates, it is expected that per capita incomes will play a larger role in driving overall food consumption. Therefore we next turn to the role of income as a determinant of consumption behavior. This includes discussions on dietary upgrading—the shift in consumption from starchy foods towards meats, dairy and processed foods—as well as the statistical evidence on how consumers’ responses to food prices and to additional income vary by income level. The chapter concludes with projections to 2050, based on the SIMPLE model, in which we explore the implications of population and income growth rates over this future period on global food demand and land use change.