Harris, Jonathan M. 1996. "World agricultural futures: regional sustainability and ecological limits." Ecological Economics 17(1996): 95-115.

Thesis:

Regional models are needed to accurately assess agricultural carrying capacity and to construct sustainable agro-ecosystems. "Future research on agriculture and regional carrying capacities must integrate considerations of the environment and sustainability, rather than relying on more abstract yield growth models" (p.112).

Summary:

Harris briefly introduces the literature on global agricultural production in relation to population growth, and evaluates neo-classical economic and the more recent ecological economic methods of estimating global carrying capacity, which are characterized by either a 'technological optimist' perspective, or a perspective focused on ecological limits. The resulting projections are drastically different. They all, however, point to the reality that the "majority of all future increases in crop production will have to come from higher output per hectare" (Crosson & Anderson, 1992, in Harris, p.97). Many regions of the world are facing extreme land constraints, not to mention water quality and availability concerns, soil degradation, and pesticide waste problems. Harris' paper is an initial attempt to assess the regional impact of ecological limits, in relation to cereal production.

World cereal production grew steadily from 1950 to 1980, slightly outpacing global population growth, providing an 0.5% increase annual increase in per capita cereal consumption. Since in 1980 there has been a leveling off of this trend, and perhaps the beginning of a decline. Harris holds that it is too early to determine whether this will be a continuing trend for cereal production, but we can be assured that there will be no letup in population growth (pp.99-100).

Harris presents projections for cereal demand and supply at the global and regional levels (pp.100-111). Based upon these analyses, he distills the following global and regional concerns (p.112):

China will have increasing import requirements, which will effect world trade balances dramatically. This may have a devastating effect on the ability of poorer developing nations to finance their food imports, "significantly worsening global inequality and world hunger" (p.109).

Yield growth in Africa, projected at 1 to 2 percent per annum, will not come close to population growth estimates (130% by 2025), and its import needs will more than double. In Latin America, agricultural yield growth problems are similar, but population growth is slower (50%), making import needs more manageable. Asia, excluding China, which would need a 2 percent yield growth rate in order to meet population needs, nevertheless will face severe limits in terms of water supplies and over-stressed soils.

Also of concern is the export capacity of the industrialized world. While yield outputs may be met through high-input agriculture, it cannot be considered sustainable from an ecological perspective. The problems of soil compaction, loss of organic matter, loss of water and nutrient retention and biological activity in soils, as well as related matters of lake, river and groundwater pollution, and increasing levels of pesticide resistant pest species call for inclusion of environmental constraints in agricultural production models (p.111).

Harris holds that the traditional framing of the world agricultural debate, with "technological optimists lining up against neo-Malthusian pessimists", has not been fruitful (p.112). He argues that a better construction of the issue would be the following:

we are undergoing a transition from a period of ever-increasing production to a period of ecological limits....Future research on agriculture and regional carrying capacities must integrate considerations of the environment and sustainability, rather than relying on more abstract yield growth models. Examination of the potential for more complex cropping systems and polycultures will be an important issue....[R]egional models of sustainable agro-ecosystems may give a better sense of true carrying capacity. (p.112)

Harris concludes with a call for greater emphasis on regional and crop-specific analysis of agro-ecosystems; greater efforts in terms of soil conservation and reclamation, efficient irrigation and water re-use, and integrating pest management systems; and greater focus upon issues of equitable and efficient food consumption and distribution, and population policy (pp.112, 113). Social and distributional equity concerns must be central to any economic analysis of world agriculture.

Keywords: agriculture, carrying capacity, population, environmental impacts, sustainability