ences in food availability and consumption represent a significant societal challenge—condemning millions in some places to persistent hunger, if not death, and fostering instability. In the coming years, cultivation on prime agricultural lands will almost certainly intensify worldwide, and marginal lands will increasingly be taken out of production (Turner, 2001). This process is already beginning in the high-income countries, often in situations where critical resources (such as water from aquifers) have been depleted. Where agricultural production continues on marginal lands, it is often supported by subsidies. Intensified production relies on significant fossil fuel and chemical inputs, as well as irrigation. The overall reduction in and intensification of agricultural lands are not necessarily being repeated in lower income countries in the tropics. There, life-sustaining, yet economically marginal farming continues to expand into the forest frontier, often following roads built for timber and other extractive industries, or corporate and large-scale agriculture seeking to capture inexpensive land (Lambin and Geist, 2006). There are no clear indications that this process will cease in the near future, although it will surely vary by region.
Globally, farmland is being lost to urbanization at unprecedented rates. The expansion of cities (see Chapter 4) is converting agricultural land to nonfarm uses (Gardner, 1997; Imhoff et al., 2004a). Between 1987 and 1992, China lost more than 1 million hectares of farmland to urbanization (Seto and Kaufmann, 2003). There is growing concern that urbanization rates in the 21st century will place significant new pressure on arable land, and that the loss of farmland to urbanization will be a threat to yield and total output (Imhoff et al., 2004a). Thus, we need to better understand the links between demographic and economic circumstances on the one hand, and agricultural production and consumption on the other.
The explosive growth in industrialized or high-input agriculture raises a set of important questions. Technologically intensive agriculture uses large amounts of fossil fuel energy, water, inorganic fertilizers, and pesticides to produce large quantities of a single crop (monocultures) or to raise livestock. The mixed history of industrialized, high-input agriculture helps explain why there was much debate about how to sustainably address the 2008 global food crisis. Many of the world’s most influential policy voices called for a renewed emphasis on food production, and particularly on increased yields through biotechnology and new green revolution approaches (e.g., Borlaug, 1995, 2000;