CIESIN Reproduced, with permission, from: Sinha, S. K., N. H. Rao, and M. S. Swaminathan. 1988. Food security in the changing global climate. In the conference proceedings for The Changing Atmosphere: Implications for Global Security, 27-30 June 1988, in Toronto, Canada, 167-192. WMO-No. 170. Geneva: World Meteorological Organization.


Socio-Economic Implications

Répercussions socio-économiques


S.X. Sinha, N.H. Rao and M.S. Swaminathan

Indian Agricultural Research Institute

New Delhi, India


Food security is defined by FAO as the physical and economic access to food for all people at all times. Swaminathan (1983) has pleaded for enlarging this concept into one of Nutritional Security, since only access to balanced nutrition and safe drinking water can ensure that every child has an opportunity for the full expression of its innate genetic potential for physical and mental development. Today, there are marketable surpluses of food grains in most developed and in some developing countries like China and India. The widespread hunger prevailing in many nations of the world is not due to the non-availability of food in the market but is due to the lack of adequate purchasing power among the rural and urban poor. Inadequate purchasing power in its turn is due to insufficient opportunities for gainful employment. The famines of jobs and of purchasing power are becoming the primary causes for the famines of food in the households of the poor.

In most developing countries, land-and-water-based occupations consisting of crop husbandry, animal husbandry, fisheries and forestry are the major sources of employment and income in rural areas. In this context, agriculture assumes a more significant role in the development of national and global food and nutrition security systems than just being the source of food. Therefore, in predominantly agricultural countries, importing food would have the additional consequence of enhancing rural unemployment, when this is done to compensate for inadequate national attention to agricultural development. Thus food security has to be viewed in the contexts of food production, job creation and income generation. An additional issue of overriding importance, if we are to ensure that today's progress is not at the expense of tomorrow's prospects, is that of conservation of the ecological base for sustained agricultural production. The various issues relating to the sustainable production of food for the growing population have been dealt with by the Panel on Food Security and Environment, of the World Commission on Environment and Development (WECD, 1987).

Although the problems we face today to promote sustainable nutrition security are staggering, we will have to be prepared to face the challenges of the future, particularly in relation to probable changes in climate. These include changes in precipitation and temperature, induced by increasing concentrations of CO2 and other industrial gases in the atmosphere. Also, with damage to the ozone layer, the incidence of UV radiation is likely to increase. We do not know the potential impact of higher levels of UV radiation on the yield of crops. These changes will have a visible impact in about 25 years from now. Whatever the magnitude of the changes may be, it will be prudent to make the scientific investment necessary to face different climate scenarios.

We should maximize the advantages of favourable weather and minimize the adverse impact of unfavourable weather on human, animal and plant populations. Since the oceans and inland waters may not be able to provide more than 5% of the total food needs, soil-based cultivation has to be the mainstay of our food and nutrition security system. But land is a shrinking resource for agriculture and we have to produce more and more food from less and less land and water in the decades ahead.

In this paper, some of the major problems and possibilities associated with food security and the projected changes in climate are discussed. The paper deals mainly with implications for the production of cereals since these are relevant to food security. Since climate effects on agricultural production and food security are important, we have considered the relevant issues under two scenarios as follows:

i) Scenario 1: Food security in the current climate regime

ii) Scenario 2: Climate change and food security


2.1 Population Growth and Food Production

The important consideration for food security is whether the food production would remain higher than the population growth rate. Between 1970 and 1982, the world population grew at a rate of 1.8% per annum but cereal production, which constitutes 94% of the total grain production, grew at a rate of 2.3% per annum. Thus food production outstripped population growth by 0.5% on a global scale. In 1986, 1942 million tonnes of food grains were produced for a population of 4915 million. Globally, this corresponds to about 395 kg of food grains per capita. But there were regional disparities to the extent that near-famine conditions occurred in many parts of the world. Thus, hunger existed amongst plenty and food production did not provide food security to everyone.

A United Nations study has projected the population size and growth rates for the periods between 1985 and 2000 and 2000 and 2025. The growth rate is likely to decline to 1.6 and 1.2% between 1985 and 2000 and 2000 and 2025, respectively. The projected world population is 6.1 billion in 2000 and 8.2 billion in 2025 (Table 1). Sanderson (1984) estimated per capita grain consumption in A.D. 2000 based on the expected per capita consumption in the recent past. Assuming that no significant changes in per capita grain consumption occur, the food grain requirements in various regions of the world were estimated (Table 1). The global requirement of food grains in 2025 is about 3050 million tonnes, including food, feed and industrial use.

It has been pointed out in the WCED (1987) report, Food 2000, that food imports are not the answer for the increasing populations in developing countries--because importing leads to growing crops with export potential. Importing food also results in unemployment in predominantly agricultural countries. Coupled with this is the poor price of exported farm commodities in developed countries. This has resulted in the increasing indebtedness of developing countries, with several undesirable ecological and political consequences.

Assuming no significant change in food consumption patterns, the projected additional demand of food grains in 2025 over that in 1986, would be 330 Mt in Africa, 130 Mt in South America, 582 Mt in Asia, 73 Mt in Europe and 16 MT in USSR. If individual regions are to be self-sufficient in food grains, the above projections lead to the following questions.

i) What changes in productivity and cultivated areas will be needed to grow the additional food grains?

ii) Will the regions requiring additional food grains be able to produce them?

2.2 Increase in Area and Productivity

Food production in different regions must increase substantially if each region has to meet its requirements. For example, production in Africa would have to increase almost fivefold and in Latin America threefold to meet the projected demand. In Asia, the required increase would be 1.75 fold whereas in USSR and Europe increases of the order of 1.25 and 1.82 fold would be needed.

In Asia and Europe, 83 and 88%, respectively, of the potentially arable land is already being cultivated (Table 2). Therefore, yield increases would be the major or almost the exclusive means of realizing the projected food grain demands of these regions. In Africa and South America, since they have only 22 and 11% of the potentially arable land under cultivation, an increase in area could be a major means of additional food grain production. The USSR will have to combine both increases in yield and increases in the area under cultivation to meet the situation.

In regions where land is available, an appropriate strategy that balances the increases in productivity with that in land area needs to be developed. The relative emphasis on each of the two components for increasing production will differ in each region. One feasible combination of area and productivity is given in Table 3. The rates of growth of area and productivity required to attain these levels of production are given in Table 4.

Globally, the estimated arable land is 3190 million hectares, of which 1406 Mha is cultivated. Cereals account for 721 Mha, or nearly 50% of the total cultivated land. The remaining cultivated land is used for other crops. Assuming no change in this pattern, 2102 Mha would need to be cultivated by 2025, accounting for 65.8% of the arable land compared with the present 44%.

2.3 Factors Limiting Agricultural Production

2.3.1 Energy

Agricultural production operations include preparation of land, use of the appropriate crop and its cultivars, application of fertilizers and pesticides, and water management. All these operations require energy. Historically, draft animals provided a major source of energy (Pimental and Pimental, 1979). With mechanization providing a more efficient means of farm operations, draft energy was gradually replaced by fossil fuels. This has lead to a gradual decrease in farm families. As a result, today in developed countries less than 5% of the total population is engaged in agriculture. However, in developing countries agriculture continues to be the major occupation of a majority of the population (FAO, 1987).

In developed countries, the main agricultural operations and inputs have remained the same up to the early 1960s. Since then there has been a qualitative change after high yielding, short-stature cultivars replaced the conventional locally adapted cultivars. The new cultivars of wheat and rice required more fertilizer and better pest management. Since the productivity of these cultivars was higher, it made mechanization imperative. This in effect led to a situation where the commercial energy input became about equal to the equivalent energy output of edible grains (Slesser, 1986). If the energy input to the whole agricultural system was estimated, from land preparation to canned provisions in Supermarkets, then the commercial energy expended was greater than the solar energy harvested by the crops. Thus it would be virtually true to say that ultimately fossil fuels serve as food in developed countries.

In developing countries, agricultural production ranges from traditional to transitional and modern. The traditional agriculture is based on the use of local cultivars, almost no inputs of fertilizer and pesticides, poor water management, and draft energy. The transitional agriculture includes improved seeds, fertilizer, pesticides, water management, but mostly draft and human energy. The modern agriculture is mostly a replica of the Western agriculture with the exception that many practices, such as weeding and harvesting, are still manual. Therefore, in developing countries, more than 50% of the population continues to work on farms.

Thus, while projecting the need to produce food grains to meet the additional requirements in each region, it is important to consider the technological level of agriculture and the source of energy. Agricultural production systems are getting transformed in Asia and Africa. Many countries are moving from a traditional to a transitional form of agriculture. However, in all these instances draft energy continues to be the mainstay of agricultural production. Both in Africa and South America, the required additional land cannot possibly be brought under cultivation with draft energy alone. Consequently, there would be a need to introduce commercial energy into agricultural production. Sinha (1986) estimated the oil requirement for producing 2412 Mt of grain to meet the world demand in AD 2000, based on U.S. commercial energy-intensive and Indian transitional agricultural production. For each tonne of grain (wheat, rice and coarse grains) the U.S. technology uses 0.110 tons of oil whereas the Indian technology uses 0.038 tons of oil (Table 5).

The implications of this to food security has to be viewed in the context of the availability of fossil fuels. If the countries with food-grain deficits have to import grains from the United States or any other country, their cost would rise, whereas the indigenous resources of these nations may not be adequate to produce the required food grains.

2.3.2 Decreasing Fertilizer Response

Fertilizers and chemical control agents form an important component of farm inputs. FAO attributed the 55% increase in yield in developing countries between 1965 and 1976 to fertilizers. This implies that fertilizer consumption in developing countries in Africa, Asia and South America would have to rise substantially in the future. However, it is likely that the fertilizer response ratio would decrease with increasing fertilizer use in the way it has happened in the past five decades (Table 6).

2.3.3 Limitations on the Genetic Improvement of Crops

A breakthrough in the improvement of rice and wheat was responsible for the world-wide increase in agricultural production, and for the green revolution in developing countries. Therefore, scientists, administrators, planners, politicians and the public have great faith in the possibility of developing new cultivars with greater yield potentials. However, it may appear surprising, though true, that the maximum yields of rice (Paddy) and wheat in experimental trials were reached in the late sixties at the International Rice Research Institute and CYMMIT (Table 7). The rice yield was 10,130 and 7476 kg ha[-1] in the dry and wet seasons, respectively, in 1966-67. In 1986 the best variety gave 8200 kg ha[-1] in the dry season but only 4100 kg ha[-1] in the wet season. The maximum yields of bread and durum wheats at CYMMIT in 1968-69 were 9313 and 8458 kg ha[-1], respectively. In 1984, their corresponding maximum yields were 8403 and 8382 kg ha[-1]. The situation for other cereals is no different. A major change in rice productivity is that the yield of some recently developed cultivars is higher on a daily basis. Nonetheless, it is reasonably clear that we may have to wait for another scientific breakthrough for a major advance in the yield potentials of various cereal crops.

2.3.4 Degradation of the Resource Base

The urgent need to meet the food demands of the growing population and of industries has led to the degradation of the agricultural resource base on almost every continent. Often the poor are held responsible for environmental degradation, including the agricultural resources. The following statements at the public hearings of the World Commission on Environment and Development (WCED) sum up the situation beautifully.

Geoffrey Bruce of the Canadian International Development Agency said "Small farmers are held responsible for environmental destruction as if they had a choice of resources to depend on for their livelihood, when they really don't. In the context of basic survival, today's needs tend to overshadow consideration for the environmental future. It is poverty that is responsible for the destruction of natural resources, not the poor".

Adolfo Mascarenhas of the International Union for Conservation of Nature and Natural Resources (IUCN) highlighted the African situation succinctly. "There are many contradictions in agricultural development. The blind imitation of models developed under different circumstances will have to give way to the realities and conditions existing in Africa. Large areas of virgin land have been opened up for export crops whose prices keep declining. This is not in the interest of developing countries."

"There are so many problems to be overcome that we forget that every problem is an opportunity to do something positive. This is an opportunity for us to think of conservation and environment in a broad educational context. In doing so, we will be able to capture the next generation and demonstrate the wonder and the benefits of the world around them".

The need for opening new land for cultivation, timber and fuelwood has caused extensive deforestation in different parts of the world. This, particularly in mountainous regions, has adversely influenced water conservation and led to soil erosion, silting and floods. Many river basins in India experience the impacts of deforestation. There is no conclusive evidence linking afforestation with precipitation but the loss of animal and plant genetic resources is clearly evident in many parts of the world.

2.3.5 Measures to be Adopted

Narrowing the gap between the maximum and the average national yields of crops would be the main objective of future research and development. Consequently, it would be important to analyse the contribution of different industrial inputs and environmental factors to assess the realizable potential of the genetically superior cultivars. The actual realization of this potential will be governed by the technologies adopted with respect to three factors:

a) land and water management

b) crop management

c) post-harvest management

These aspects have been discussed in sufficient detail in "Food 2000" (WECD, 1987).


Food production in any given year is affected most directly by the values of the critical climate elements (temperature, radiation, precipitation, etc.) during the year. The stability of available food supplies is governed by the interannual variability of these elements. Access to food supplies in different regions of the world is determined by their share of the food production, the role of cereals in the diet of the people, and the various political and market forces that act upon the global food security system. The climate anomalies that occurred during the 1970s caused fairly small fluctuations in the world cereal supply. But they occurred at a time of an increasing use of cereal as livestock feed. The food shortages were particularly severe in the Soviet Union and its large grain purchases led to dramatic fluctuations in world cereal prices. The disastrous effects these had on the world food security system are now well documented (Garcia, 1981).

Climate fluctuations of the kind witnessed in the 1970s lie within the variability of the present climate. They could have been anticipated by prudent societies if an eye had been kept on the climatic record. In addition to the normal variability of the climate, there is increasing evidence for a change in atmospheric optical properties as a result of the buildup of CO2 and other "greenhouse gases". It is also clear that their buildup will continue. It is expected that in the long term this will result in "climate change".

Mathematical models of the potential climatic impact of such a change have been developed by various groups. Such models attempt to predict the changes in critical climate elements for a doubling of the CO2 concentration. Although there is little agreement between various models about the specific magnitudes of the regional changes during the next 50 to 100 years, and details needed for regional planning, there is considerable agreement on the global changes, which may be summarized as follows:

  1. The lower atmosphere will warm and the stratosphere will cool.

  2. The annual average global warming will be 1.5 to 4deg.C. This is much greater than any natural climate change. The rise in temperature is, in general, greater in the Northern Hemisphere than in the Southern Hemisphere and increases (by a factor of 2 to 3) polewards.

  3. The temperature rise will be greater (by about 50%) in winter than in summer. Consequently, we may expect the production of winter season crops to be more affected than that of summer crops.

  4. Freeze-free periods will lengthen in higher latitudes so that larger areas may be brought under cultivation, if soil conditions are suitable. The increase in the freeze-free period will depend on the current length of this period, e.g., a 1deg.C rise in temperature will lengthen an 80-day freeze-free period by about 20 days but a 120- to 130-day period by only 6 days.

  5. General warming will be accompanied by a weakening of temperature differences between the equator and the poles, which will affect the atmosphere's general circulation. This could lead to longer dry periods.

  6. The global average annual precipitation will increase by about 7 to 11%, but its regional and temporal variations are uncertain.

  7. Relationship between precipitation and evaporation is not likely to change in the lower latitudes. Evaporation will increase more than precipitation in the mid- to higher latitudes.

  8. Soil moisture conditions will be "wetter" in some regions of the world (35deg.N-35deg.S), but "drier" in others, compared with present conditions.

  9. A sea-level rise is foreseen but its magnitude and time-scale are uncertain. The effects on agriculture in coastal regions could be disastrous.

  10. Agroclimatic zones will shift poleward (about 100 km per degree of warming).

  11. The variability of temperature and precipitation may decrease because of the weaker circulation. The regional variations are uncertain.

  12. Only changes in mean climate conditions are specified by the models. Sizeable uncertainties remain about the timing, intensity and direction of specific effects.

However, it may be noted that climate is a complex, non-linear multiple feedback system with dominant positive feedbacks. From a cybernetic systems viewpoint, a fairly rapid forced change in such a system, such as a change in the CO2 concentration, is likely to destabilize the system. The magnitude of the destabilization tends to be proportional to the rate of change of the forcing function. Because the rate of change of CO2 concentration is expected to be greatest between 2000 and 2060, these decades may experience chronic and severe weather variability (Markley and Hurley, 1983). One aspect of the climate change, even at the present level of CO2 increase, is provided by a simulation study of Rowntree and Bolton (1983). They showed that, as a result of positive feedback, a hot, dry spell occurring in midsummer in central Europe, when coupled with a weak atmospheric circulation pattern, could persist for as long as 50 days and expand into Scandinavia, Spain and North Africa. Even under conditions of moist airflow, initial hot, dry conditions maintained themselves for up to 20 days.

Thus, even though mean changes in the global climate resulting from a doubling of CO2 concentration can be anticipated, the specific changes in the annual variability of climate are uncertain during the period when the doubling is occurring. But, keeping with the complex, non-linear and multiple feedback characteristics of the climate system, it is likely that the next 50 to 100 years will experience chronic and severe climate variability.

What are the implications of climate change for the world food security system? To answer this it is necessary to examine the effects of climate change on both the regional food production as a result of changes in mean climate, as well as the variability of the food production resulting from increased climate variability. In the ultimate analysis, the annual variability of total food production as well as the regional share of production are the determinants of food security.

3.1 Effects of Climate Change on Food Production, Increased CO2 Concentration and Crop Yield

The climate changes envisaged in the next century are mostly attributed to the increasing concentration of CO2 and other "greenhouse gases". Since CO2 is an essential reactant in photosynthesis to produce organic matter, it was postulated that farmers could look forward to better harvests (Wittwer, 1986). Often these postulates were based on short-term experiments in controlled environments or glasshouses with adequate supplies of water and plant protection measures. Rosenberg (1987) made an analysis of gas exchange and concluded that climate change, at least as far as CO2 concentration effects are concerned, may prove advantageous. However, Gifford (1987) made a more cautious assessment of CO2 effects by including temperature change as an additional component. The following observations are relevant for assessing the effects of climate change, including CO2 concentration, on crop yields:

  1. The highest yields in C3 crops are obtained around a mean daily temperature of 15deg.C and in C4 crops around 30deg.C.

  2. The temperature optima for vegetative growth and the reproductive phases are often different. An increase of temperature beyond a mean of 22deg.C causes sterility in rice resulting in reduced grain yield, though it has no effect on photosynthesis (Figure 1). In wheat, an increase in mean temperature above 16deg.C results in a decrease in grain weight and a poor yield (Figure 2). A higher temperature significantly reduces tillering, which is essential to building shoot population.

  3. The crops having a high growth rate in the preflowering phase usually deplete soil moisture, which is necessary to normally complete the grain development phase. Consequently, high initial growth, in the absence of irrigation, results in a poor grain yield despite high dry matter accumulation.

Gifford (1987) estimated the rise in temperature that would cancel out the advantageous effects of CO2 fertilization (Table 8). At locations ranging from 50deg.N in Canada to 37deg.S in Australia a rise of 1.5deg. to 2.4deg.C is required to cancel the advantageous effects of CO2 on grain yield, presumably under irrigated conditions. In the absence of irrigation, crop yields may in fact be reduced.

The optimistic predictions for agricultural production made by several people in the recent past based on CO2 fertilization effects should not lead to complacency about the question of food security. These projections have been based on a study of the individual effects of only one or two factors. It should be recognized that agricultural production is a complex process. The available evidence on CO2 fertilization effects, when two or more factors are simultaneously considered is, at best, inconclusive.

3.2 Effect of Changes in Mean Temperature and Precipitation

Crop production is directly influenced by temperature and precipitation. Both are critical elements for determining the agroclimatic zones. Temperature determines the duration of a crop's growing season and controls its phenological development and water requirements. Precipitation provides the critical input for crop growth, water. The distribution of these variables during the period of crop growth is also critical. But, information on intraseasonal variations in temperature and precipitation in the 2 x CO2 climate is not available. This discussion is, therefore, limited to anticipated changes in seasonal/annual values of the variables. The direct effects of CO2 on crop yields are excluded since the available information is inconclusive.

In general, an increase in the average annual temperature will result in shorter freeze periods than now. As a result, larger areas can be brought under cultivation at the climatic margins. But, in the existing crop belts, the growing season duration will be reduced and productivity (crop yield) losses will result. Some crops may also be forced out of cultivation to be replaced by others. To what extent the losses in crop yield can be compensated by the increases in crop area is uncertain and will be governed to a significant extent by technology. An increase in precipitation will have beneficial effects on both productivity and crop area.

Wheat, rice and maize are the three major crops of the world accounting for about 80% of its total cereal production in 1985. The impacts of changed climate conditions on their production, when considered independently and assuming current levels of technology, are shown in Tables 9(10) to 11. The climate scenario considered here is based on temperature changes predicted by the GFDL model for various regions (latitude limits) for the summer and winter seasons. This model predicts the maximum increases compared with those of other commonly used models, GISS and NCAR (Rosenberg, 1987). Precipitation scenarios are considered indirectly by using the results presented by Kellogg and Schware(1981). The impacts on production are indicated as increases (+) or decreases (-) over current crop yields or areas. The results are presented for the countries/regions that accounted for significant shares of each crop's production in 1985.

Based on Tables 9(10)-11, the following observations may be made:

  1. In mid- to higher latitudes (developed countries) significant increases in area, accompanied by reductions in crop yield are expected. In the lower latitudes, because of increasing temperature, significant areas become unavailable for wheat and yields will also decline. An increase in water requirements may be anticipated in all regions in these latitudes, and irrigation management will acquire a greater significance. A net reduction in wheat production is anticipated, with the balance of production shifting further in favour of developed countries.

  2. About 94% of the rice is grown in developing countries mostly during the summer monsoon. However, better yields are obtained in the dry season when temperatures are lower and pest problems are fewer. An increase in precipitation would help increase the area of this crop and its yield, but an increase in temperature promotes sterility and yields would be reduced. Almost one third of the rice is grown under upland unirrigated conditions that may benefit from increased precipitation. On a balance it would appear that developing countries will continue to be major growers of rice, and this crop will continue to be a major diet of the people in these regions.

  3. The mid-latitudes account for more than 50% of the maize production. Increased precipitation may increase the share of the developing countries in the world's maize production.

Overall, the declines in the production levels of wheat are expected whereas the production of rice may remain unaffected and maize may increase, under a doubled-CO2 climate. The existing wheat production imbalances in favour of the developed countries may be further accentuated. Similarly, the share of developing countries in rice production may also rise. Maize production may become more uniform across developed and developing countries.

The above analysis excluded the possibility of replacing one crop by another more suitable for the changed climate conditions. But this is expected to happen. For example, wheat belts may be replaced by barley, barley by maize, maize by sorghum and so on. Rice may be substituted if adequate irrigation facilities are available. But these substitutions are likely to take place only gradually since there will be problems of adaptation.

The current advantage, with respect to food security, remains with the developed countries primarily because of the rapid progress of technology or the absence of population pressure or both (see the 1985 yields of various crops in (Tables 9(10)-11). Based on currently available information it is clear that these two factors will continue to be the significant determinants of food security, whether a climate change occurs or not.

3.3 Effects of Climate Change on Pests and Diseases

Currently about 25% of food is lost as a result of pest damage. Today the high productivity of various crops in temperate regions could be attributed not only to improved technology, but also to the limited number of diseases and pests, better soil health including microflora and better response to fertilizers. The generally warmer and moist conditions in the changed climate coupled with a low general circulation and longer freeze-free periods are highly conducive to crop pests. By far, the most predictable effect of climate change is that it will cause significant increases in the pest populations. Thus, some of the advantages of existing temperate regions may be canceled by increased temperature and uncertain precipitation.

3.4 Climate Change and Variability of Food Production

Under the current climate, the coefficient of variation (CV) of the global total cereal production for the trend in the 1970s was about 3% (Anderson et al., 1987), but is higher in some individual countries. The variability is greatest in semi-arid areas and least in humid areas. The regions of high variability also have low average crop yields. CV also tends to be less in larger countries because risk pooling is spread across regions and crops.

For individual crops at the global level, the CVs of maize, sorghum, wheat and rice around the trend are about 4, 6, 5 and 4%, respectively, but are higher in individual countries. For example, in India, the CVs of wheat, rice and sorghum are 11, 8 and 16%, respectively. In the United States, the values for maize, winter wheat and sorghum are 10, 10 and 11% respectively (Hazell, 1984). Some of the sources of inter-annual variability in national agricultural production are:

i) Variability of weather

ii) Variability of areas sown under different crops

iii) Variability of yield correlations between regions and crops

iv) Production expansion into riskier regions

v) Increased sensitivities of new technologies to weather and disease

vi) Variations in agricultural prices, policy and levels of rural infrastructure

The relative contribution of these factors to the overall variability of food production is different in different regions. It also depends on the current level of production variability in the region. For example, the variability in cereal production in India was shown to be (Hazell, 1984) a consequence of the increased adoption of high yield technology and the variability of weather, crop yields, areas cropped and prices. On the other hand, the predominant sources of production variability in the United States were crop yields and yield correlations between states.

In this context the question relevant to food security under future CO2-induced changes of climate is whether such climate changes will lead to an increased or decreased variability of food production. Even when anticipated changes in mean climate conditions only are considered, it is clear (from the previous section) that an increased variability of production would result from sources (ii) to (v) listed above. When an increased variability of weather (i) resulting from climate change is also included, significant increases in the variability of food supplies are foreseen.

This leads to many concerns that need to be addressed by the international community. Prominent among these are: perceptions of increased risk that may discourage the adoption of new technologies and retard agricultural growth; increased instability of national and international food supplies; increased frequencies of droughts and floods over larger areas; increased destabilizing effects of agricultural prices on food production and consumption; and risk pooling across regions and crops by diversification of the crop production systems.


Climate fluctuations influence the lives of millions of people around the world. There are now several studies on the interaction of climate and society (Kates et al., 1985). Whether climate change induced effects could be discerned as a warning or as an attempt to mitigate adverse effects are important questions. Parry et al. (1987) have developed a methodology based on climate impact assessment in marginal areas. This is useful when the objective of such studies is to evaluate the sensitivity of ecosystems to climate changes However, food security is concerned more with stabilizing the available food supplies. Both national and global food security are dependent more on the stable and productive areas than on the marginal areas. For example, in India, seven out of 35 meteorological divisions are important determinants of food security (Sinha, 1987). This is clear from the impact of droughts of nearly equal magnitude on national food production in the two years, 1979-80 and 1982-83. There was a 17% shortfall in grain production in 1979-80 compared with the previous year's 131.4 Mt. However, in 1982-83, food grain production declined by only 3.7% relative to the previous year's 133.3 Mt. This was because, in this year, the highly productive divisions were not affected (Sinha, 1987). Therefore, for the assessment of food security, it is necessary that the impact of climate fluctuations on productive areas be studied as well. For studying global food security, it may be prudent to perform such studies on a selected group of nations.


5.1 Conclusions

  1. The projected population growth rates and the ensuing food demands, even in the current global climate, would make it difficult to provide for human sustenance and food security in the twenty-first century.

  2. Africa and South America are the most vulnerable regions in regard to food security. The food demands of these regions can be met by increasing the cultivated area. Asia is next in order of vulnerability. Significant increases in crop productivity are required in this region since it is difficult to bring additional areas under cultivation. Appropriate strategies for increasing agricultural production that balance an increase in cultivated area with an increase in crop productivity need to be designed for various regions of the world.

  3. There is a near-consensus that the rising concentrations of CO2 and other greenhouse gases in the atmosphere will lead to a climate change. This will directly affect agricultural production and food security.

  4. Some recent reports on the favourable impact of climate change on agricultural production should not lead to complacency. The available evidence in support of this is inconclusive and is not based on the complex dynamics of interactions between agricultural production processes and the environment.

  5. Two aspects of the effects of the changing climate on agricultural production and food security need to be considered:

    i) Changes in the mean values of the critical variables that will affect the trends of global agricultural production and the regional shares of production.

    ii) Increased instability of climate that will result in greater instabilities in food supplies.

  6. In the 2 x CO2 climate, an overall decline in production of wheat may be expected as a consequence of an increase in temperature in mid-latitudes. The production of rice may be unaffected whereas that of maize may increase as a result of the increased area and wetness in lower latitudes. Food supplies in smaller nations are likely to be affected more by the climate change compared with those in larger nations. This is because of the advantage of risk pooling across regions and crops in large nations.

  7. Even in the changed climate, the current balance of food supplies in favour of the developed nations will continue. In the future also, even more than now, technology and resource management will continue to determine this balance. The availability of energy, the decreasing marginal response of crops to fertilizers relative to that in the 1960s and 1970s, the leveling off of the production potential of major cereals and the eroding natural resource base will be the major limiting factors on the agricultural technology of the future.

5.2 Implications for Research and Policy

  1. Measures to improve food security by maintaining adequate food reserves and developing efficient transportation and distribution networks require huge capital resources. The planners in many small nations are reluctant to commit the financial resources required to establish such networks. But in a changing climate, the smaller nations will also be the most vulnerable in regard to food security. Such nations may be encouraged to group and pool the resources required for stepping up food security measures. This will also provide the advantage of risk-pooling across regions and crops, and the group of nations as a whole will be less susceptible to climate effects. In the long term, the adoption of food security measures will come to be viewed in the broader context of regional development. Specific studies need to be initiated on the criteria to be adopted for forming the nation groups, the crops and production technologies required, the appropriate balance between increasing crop area and productivity, and the related aspects of infrastructural development such as transportation, distribution and marketing networks.

  2. In the future, particularly in the changing climate conditions, to ensure food security will require a greater emphasis than now on land and water management, crop management and post-harvest management. The availability of energy will be a significant factor affecting production. Developments in the use of non-polluting, renewable resources of energy will play a significant role in conserving the resource base of agricultural production. Any major breakthrough in this sector, should be globally shared without reservations about political, social or economic considerations. Such a breakthrough, in addition to supporting agricultural production, would help control the "greenhouse effect" itself and will be to the benefit of mankind.

  3. Considerable additional research is required on the annual, seasonal and intraseasonal variabilities of climate in individual regions. Linkages between the results of this research and agricultural production need to be established. The predictive power of GCMs has to be extended considerably before this can be done.

  4. An important issue of research, in the context of food security, relates to the methodology of climate impact assessment. Current methodologies, developed for impact assessment in marginal areas, are not directly applicable. Such methodologies are useful as long as the goal of research is to analyse and demonstrate the sensitivities of agroecological and social systems to climate change. In this case, the marginal areas provided the analytical advantage required for isolating the effects of climate variables. However, to provide food security, the major source of food is agricultural production in regions with a high potential for production. In these regions, it is difficult to isolate the climate effects from other factors. Thus, on the question of food security in a changing climate, methodological issues relating to climate impact assessment need to be critically addressed.

  5. Specific research is required on the costs of not considering the effects of climate change when planning and designing agricultural production and food security systems with lifetimes of several decades. Examples are irrigation systems and agricultural expansion in coastal areas.

  6. The instability of food supplies results from various sources. These include, in addition to climate variability, the uncertainties in agricultural policy. Whereas the effects of climate variability are difficult to anticipate and control, the resulting instabilities may be minimized through appropriate food policy. This requires from individual nations explicit statements about their food policy objectives (efficient growth of agriculture and related sectors, income distribution through employment, subsidies, insurance, etc.), and their specific programs and policies, not just projects. Many projects in tropical Africa achieved only a limited success because a framework for monetary, fiscal and trade policy did not exist.

  7. In recent times, considerable progress has been made in drawing the attention of policy-makers to the issues related to climate change. But much more persuasion is needed before their interest gets translated into public policy and action. This requires developing the capabilities for obtaining and analysing information, developing policy alternatives and presenting them to development planners to initiate action. Simultaneously, it must be recognized that the political will to initiate action is driven by public opinion. Informed public opinion must be mobilized through the systematic communication of available research information.


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