Future Trends and Issues Facing World Agriculture

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An important aspect of the impact of climatic change on agriculture is the social, economic and agricultural system context in which climatic change will occur. The conditions of the social, economic and agricultural system in a country can affect the capacity to adapt, the vulnerability of society, and the anticipatory response of society to climatic change. People in isolated areas, who are highly dependent on local agriculture for income and food and without social support systems to assure food for the hungry in times of need, are likely to see more severe impacts than people in a wealthier country. In such a situation they may lack financial resources to change production practices, will see the consequences of production shortfalls reflected as more severe human consequences such as hunger and malnutrition, and may be less able to take effective anticipatory actions. The above considerations mean that the social and economic conditions across the world and future changes in these conditions will affect how people will be affected.

Some commentators (e.g. Erlich and Erlich, 1990) worry that rising demand for food over the next century due to population growth will lead to increasing global food scarcity and a worsening of hunger, malnutrition and associated problems in developing countries. Climatic change could thus exacerbate a bad situation. Concern about the ability to meet food demand stems from the observations that most of the potentially arable land is already under cultivation and much is suffering degradation, freshwater supplies are dwindling, and only a small amount of less fertile land remains to meet additional future needs.

More conventional agricultural economic modelling (e.g. Mitchell and Ingco, 1995) suggests that the world food situation is likely to improve, given assumptions about agricultural productivity growth. The world's food system might thus be less vulnerable to climatic change. This view is supported by past evidence of declining global food scarcity and real prices for food commodities, and recognition that while population continues to grow, the growth rate has slowed. For example, an index of food commodity prices by the World Bank (1992) shows an overall decline of 78% between 1950 and 1992. Increasing yields and improving agricultural productivity appear to be largely responsible for this trend; although farm subsidy increases in Japan, the EEC and the USA through the 1970s and into the 1980s may also have contributed.

Behind these different views of future world food security are different views about three broad forces that affect the world's food situation. These are: (i) demand growth due to rising populations and incomes; (ii) natural resource (land, water) availability and degradation of these resources; and (iii) the continuing ability of agricultural research to boost productivity and yields.

21.6.1 Future demand growth

For the future, there is a general consensus among forecasters that world population will be 8-9 billion by 2025 (McCalla, 1994), implying a growth rate of approximately 1.3% year-1 from the 6 billion population in 1998 - less than the 1.5% year-1 growth since 1970. Parikh (1994) estimates that world population will be 10.3-12.8 billion by 2050, based on extensions of UN (1994) estimates, implying a further slowing of the growth rate to around 1.1%. Studies projecting the impacts of climatic change around the middle of the 21st century (Chen and Kates, 1994; Fischer et al,, 1994; Rosenzweig and Parry, 1994) have assumed world population levels of approximately 10 billion. Nearly all (95%) of the predicted population increase is in the developing world, and the rate of growth is greatest in Africa, where population is projected to increase three- to fivefold over the 1990 level.

Demand for food will also increase with income. Table 21.3 shows projections for future real income growth by Fischer et al, (1994) for 1980-2060. Over this period, growth is expected to be a little higher in the developing countries (2.4% year-1) than in the developed world (1.6%). However, in absolute changes, in per capita terms, the picture is not quite so optimistic for the developing world. The World Bank (1992) predicts that by 2030 real per capita income will increase by US$160 in sub-Saharan Africa to $500, by $1500 in Asia-Pacific to $2000, by $3200 in the Middle East/North Africa to $4000, and by $3300 in Latin America to $5500. Even though growth rates are more rapid than in the developed world, per capita income levels remain below current levels in the major developed countries.

Income and population growth rates are the basis of demand growth projections of models such as those of Fischer et al. (1994) (Table 21.4). Parikh (1994) finds that caloric demands increase between 1.5 and threefold by 2050 over the 2000 levels. The projected demands for cereals in Fischer et al. (1994) are broadly consistent with these estimates. The estimates display no particular bias toward growth in meat and dairy products, as might be expected with rising incomes, although Parikh's estimates show a wide range of possible growth in dairy products and meat.

The extent of shifts in the aggregate consumption among agricultural products depends on how income increases are distributed among income classes. Growth in income of the poorest will mean greater demand for basic foods such as grains, pulses and potatoes as they increase their basic calorie intake. Income growth concentrated among the wealthier segments of the populations in developing countries could generate more of a shift toward

Table 21.3. Projections of GDP growth. (Source: Fischer et al., 1994.)

Region 1980-2000 1980-2060

Developed 2.6 1.6

Developing 4.3 2.4

Africa 4.6 3.0

Latin America 3.9 2.1

Southeast Asia 4.7 2.4

West Asia 4.4 2.8

Table 21.4. Projected global production of food commodities in 2060. (Source: Fischer et al., 1994.)



















Coarse grains






Bovine and ovine meat












Other animal produce






Protein feed






Other food


















aWheat, rice, course grain in million tonnes; bovine and ovine meat in million tonnes carcass weight; dairy products in million tonnes whole milk equivalent; other animal produce, and protein feed in million tonnes protein equivalent; other food in 1970 US$ billion.

aWheat, rice, course grain in million tonnes; bovine and ovine meat in million tonnes carcass weight; dairy products in million tonnes whole milk equivalent; other animal produce, and protein feed in million tonnes protein equivalent; other food in 1970 US$ billion.

meat and dairy products if these consumers adopt consumption patterns more like those displayed by consumers in wealthier countries. The extent to which consumption patterns of different societies reflect cultural differences or income differences, and hence the extent to which patterns will change as income increases, remains a subject of research.

The implications of demand growth resulting from income growth vs. population growth are also quite different. Income-generated growth means that at least some people are eating more, while population-generated growth means that per capita consumption will fall if production does not keep pace. Income-generated growth, when income growth occurs mainly among the wealthier segments of society, could worsen the food situation for the poor. Rising demand by wealthier food consumers would increase prices and, by placing additional demand on the world's resources, make it more difficult for the poor to afford food. Whatever the trend, there is general agreement that the bulk of the future demand increase will come from the developing world, since in developed countries the average person is already reasonably well fed.

Can these demands be met? The projected food demands of the developed countries (USA, Canada, Europe, Japan, Australia and New Zealand) only increase modestly above their current levels in the study by Parikh (1994). Given that these countries as a group are essentially self-sufficient in agriculture at the moment, Parikh (1994), Crosson and Anderson (1994) and others predict that they can probably satisfy their future food demands relatively easily. Indeed, Mitchell and Ingco (1995) predict that net grain exports of the developed countries will increase from their current level of 117 Mt to 194 Mt in 2010; thus they see the developed countries as growing in importance in feeding people in developing countries.

One limit of these studies is that they do not directly consider resource availability and quality. Instead they extrapolate yield growth rates, assuming that productivity enhancements can more than overcome any effects of resource degradation. Typically, however, yield growth rates are assumed to slow in the future, but, with population growth rates slowing as well, growth in agricultural supply can still outpace growth in demand.

21.6.2 Resource availability and quality

While existing global food demand and supply models generally do not explicitly consider resource degradation, there is a variety of analyses that have considered resource issues that could constrain increases in agricultural production. One approach to considering resource adequacy is carrying capacity. Table 21.5 shows estimates from a United Nations Food and Agriculture Organization (FAO) study by Higgins et al. (1982) of the maximum population that could be supported by the available quantity of land and other resources in developing countries (China was not included in the analysis). This approach tends to show that the capacity supports much higher populations than were projected at that time for the year 2000, and indeed through

Table 21.5. Population carrying capacities of developing countries. (Source: Parikh, 1994.)

Total land area

Population in 2000

Persons ha-1 in

Potential population-supporting capacity in 2000 (persons ha-1)


(million ha)



Low inputs

High inputs













S.W. Asia






S. America






C. America






S.E. Asia






2050 in all regions of the world, if high levels of inputs are used. At an average of 5.11 people per hectare with a high level of input use and total land availability of 6.495 Gha, these estimates suggest that a total population of 33.2 billion could be supported. The projected demands in Parikh (1994) imply a 50% higher calorie intake than in the FAO study; adjusting for this, the population carrying capacity of developing countries is still 22.1 billion.

A number of caveats are associated with carrying capacity calculations. Obviously, key to the calculation is the level of inputs applied at low-input levels. Carrying capacity would be exceeded in some regions over the period to 2050. A well-functioning economic system should provide the incentive to intensify production as needed to meet demand. However, impoverished people suffering from hunger lack the income to have their food needs realized as demands that are recognized in an economic system. Hence, the agricultural production system will not respond to produce this food unless these demands are realized in the market, either by solving problems of poverty or by developing food assistance programmes that provide food for the poor.

Other assumptions of carrying-capacity calculations are also open to question. Typically the estimates assume that many areas that currently achieve low yields and production rates could achieve yield and production rates like those in other high-yield areas. Existing data do not support a full analysis of whether the resource conditions actually exist to support these production levels. The open debate is whether yields are low in some areas because resource conditions do not support higher production or because high yielding farming practices have not been adopted and, if so, under what economic conditions they would be adopted. Expanding agricultural land area and intensifying production may also impose significant environmental costs, including threats to biodiversity, water quality and natural ecosystems. Limits on input use and land expansion to reduce such impacts are generally not taken into account in these carrying-capacity calculations. On the other hand, these calculations assume existing technologies and do not factor in possible improvements in yields and productivity. A number of these issues have been addressed in separate analyses.

Land resources

Crosson and Anderson (1994) argue that a potentially important constraint on increasing the supply of cropland is that much of the uncultivated land is in areas that are poorly connected by roads, rail and air to existing domestic and foreign markets. Moreover, efforts to preserve natural forestlands could exclude much of the uncultivated land from conversion. As a result, they see little new land being converted.

The other land resource concern is degradation of existing agricultural land, with consequent effects on productivity. Soil erosion, compaction, nutrient depletion and desertification are principal dryland degradation concerns. Table 21.6 reports estimates of percentage of dry land suffering from degradation or desertification, based on estimates of FAO and reported by Norse (1994). These estimates show 70% of agricultural land and more for most continental regions as degraded. Unfortunately, these data do not indicate the extent to which degradation is affecting yields. Soil erosion, while degrading water quality in streams, rivers and estuaries, can have modest effects on yields and may be correctable by improved farming. For example, one study for the USA by Crosson (1992) suggested that in the long run these losses are typically small relative to the gains from technological progress.

These results may not be transferable to many developing countries. Soils in tropical areas are in general thinner, more vulnerable to erosion and less easily restored. Sustainable agricultural production has often been difficult to achieve on nutrient-poor soils. For example, in Brazil's Amazon region, government policies in the 1980s encouraged the conversion of tropical forests to crop and livestock production. Much of this land has since been abandoned (Repetto, 1988; Binswanger, 1989; Mahar, 1989).

Of the 3569 Mha that has so far been degraded in dryland areas of the world, 29% is in Africa and 37% in Asia, where desertification has been thought to be a significant problem. There is continuing debate about how to define desertification as well as its causes, extent and consequences. With respect to cause, the issue is whether it results from non-sustainable production practices or climatic variation on the order of a decade or so and how these factors interact. Nelson (1988) and Bie (1990) concluded that the incidence of desertification is a lot less than originally thought and that the contribution of desert margins to food production is small. For example, low-rainfall areas accounted

Table 21.6. Desertification and dry land degradation. (Source: Norse, 1994.)


Total dry land area in agriculture (Mha)

Area degraded (Mha)

Dry land area degraded (%)

















N. America




S. America








for only 12% of domestic cereal production in sub-Saharan Africa and 1% in Asia in the early 1980s (Norse, 1994). There is also considerable controversy as to whether and under what conditions desertification is reversible.

Another potential threat is salinization of soils and water. Mainly a problem for irrigated areas, salinization also occurs in hot dry climates, where evaporation can increase salt concentration in soils. In irrigated areas, salinization is usually the result of poor construction, inadequate maintenance of canals, or excessive use of water. The end result is waterlogging, salinization, reduced crop yields and ultimately the loss of agricultural land. The UN (1992) estimated that 1-1.5 Mha year-1 are lost because of this process, with another 30 Mha being at risk.

Water resources

Water resources are important for agriculture. While only 17% of global cropland is irrigated, this 17% of land accounts for more than one-third of world food production. An estimated additional 137 Mha have potential to be irrigated, compared with the 253 Mha currently irrigated (World Bank, 1994). As with land resources, the cost of developing these irrigation systems may be prohibitive. Current water systems in many developing countries achieve low efficiencies of water distribution and average crop yields are well below potential (Yudelman, 1993; Crosson, 1995; Agcaoili and Rosegrant, 1995).

As already mentioned, soil salinization from poorly designed and managed irrigation systems is a problem. Another concern with irrigation is the spread of waterborne diseases. Unpriced and heavily subsidized water resources, inadequate planning and maintenance of water systems, unassigned water rights and conflicts among goals are seen as sources of these problems (Repetto, 1988). Solutions to these problems are available in most cases, and a recent study found that investments in irrigation have been at least as profitable as investments in other agricultural enterprises (World Bank, 1994). Perhaps the most important solution is to move to full cost pricing of water. Full cost pricing would encourage adoption of water-conserving practices while providing funds to maintain and improve management of irrigation and drainage systems.

Technological innovation and adoption

The invention and diffusion of yield-enhancing technologies and farming practices have been more important factors in raising global agricultural output over the last 50 years than the expansion in quantities of land and water (Crosson and Anderson,1994). There is debate about whether the trend toward ever higher yields can be maintained. Some see evidence in recent history that yields may have reached a plateau; Reilly and Fuglie (1998), however, see no evidence of an absolute plateau in yields for major field crops in the USA.

Reilly and Fuglie (1998) also review evidence beyond simple time-trend statistics. As mentioned with regard to carrying capacity, a gap in yields among sites is often taken as evidence of an opportunity to increase production. Related research tasks include: (i) sustaining present yields, recognizing that yields will erode without maintenance research; (ii) closing yield gaps between low- and high-yielding areas; and (iii) increasing ideal condition yield ceilings. Agronomic potential for increases in the future may come from: (i) more attention to soil, water and other environmental factors, as most attention to date has been on genetic factors; (ii) management of the production process; and (iii) aspects of plant growth and yield, such as increasing the photosynthetic rate, observing that much of the past gains in yield have come from increasing the harvest index (grain-to-straw ratio). One study made what was considered reasonable adjustments in the harvest index, photosynthetic efficiency, pest management, leaf area and harvest efficiency for several crops to generate yield increases of 70-80%. They assumed that these could be achieved in 30-40 years. The increase was equivalent to a 1.3-1.6% per year rate of exponential growth, not unlike the rates assumed in global agricultural studies.

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