Originally published in Science Express on 28 January 2010
Science 12 February 2010:
Vol. 327. no. 5967, pp. 812 - 818
BY H. Charles J. Godfray, John R. Beddington, Ian R. Crute, Lawrence Haddad, David Lawrence,James F. Muir, Jules Pretty, Sherman Robinson, Sandy M. Thomas, Camilla Toulmin
Continuing population and consumption growth will mean that the global demand for food will increase for at least another 40 years. Growing competition for land, water, and energy, inaddition to the overexploitation of fisheries, will affect our ability to produce food, as will the urgent requirement to reduce the impact of the food system on the environment. The effects of climate change are a further threat. But the world can produce more food and can ensure that it is used more efficiently and equitably. A multifaceted and linked global strategy is needed to ensure sustainable and equitable food security, different components of which are explored here.
The past half-century has seen marked growth in food production, allowing for a dramatic decrease in the proportion of the world’s people that are hungry, despite a doubling of the total population (Fig. 1) (1, 2). Nevertheless, more than one in seven people today still do not have access to sufficient protein and energy from their diet, and even more suffer from some form of micronutrient malnourishment (3). The world is now facing a new set of intersectingchallenges (4). The global population will continue to grow, yet it is likely to plateau at some 9 billion people by roughly the middle of this century. A major correlate of this deceleration in population growth is increased wealth, and with higher purchasing power comes higher consumption and a greater demand for processed food, meat, dairy, and fish, all of which add pressure to the food supply system. At the same time, food producers are experiencing greater competition for land, water, and energy, and the need to curb the many negative effects of food production on theenvironment is becoming increasingly clear (5, 6). Overarching all of these issues is the threat of the effects of substantial climate change and concerns about how mitigation and adaptation measures may affect the food system (7, 8).
A threefold challenge now faces the world (9): Match the rapidly changing demand for food from a larger and more affluent population to its supply; do so in ways that are environmentally and socially sustainable; and ensure that the world’s poorest people are no longer hungry. This challenge requires changes in the way food is produced, stored, processed, distributed, and accessed that are as radical as those that occurred during the 18th- and 19th-century Industrial and Agricultural Revolutions and the 20th-century Green Revolution. Increases in production will have an important part to play, but they will be constrained as never before by the finite resources provided by Earth’s lands, oceans, and atmosphere (10).
Patterns in global food prices are indicators of trends in the availability of food, at least for those who can afford it andhave access to world markets. Over the past century, gross food prices have generally fallen, leveling off in the past three decades but punctuated by price spikes such as that caused by the 1970s oil crisis. In mid-2008, there was an unexpected rapid rise in food prices, the cause of which is still being debated, that subsided when the world economy went into recession (11). However, many (but not all) commentators have predicted that this spike heralds a period of rising and more volatile food prices driven primarily by increased demand from rapidly developing countries, as well as by competition for resources from first-generation biofuels production (12). Increased food prices will stimulate greater investment in food production, but the critical importance of food to human well-being and also to social and politicalstability makes it likely that governments and other organizations will want to encourage food production beyond that driven by simple market mechanisms (13). The long-term nature of returns on investment for many aspects of food production and the importance of policies that promote sustainability and equity also argue against purely relying on market solutions.
So how can more food be produced sustainably? In the past, the primary solution to food shortages has been to bring more land into agriculture and to exploit new fish stocks. Yet over the past 5 decades, while grain production has more than doubled, the amount of land devoted to arable agriculture globally has increased by only ~9% (14). Some new land could be brought into cultivation, but the competition for land from other human activities makes this an increasingly unlikely and costly solution, particularly if protecting biodiversity and the public goods provided by natural ecosystems (for example, carbon storage in rainforest) are given higher priority (15). In recent decades, agriculturalland that was formerly productive has been lost to urbanization and other human uses, as well as to desertification, salinization, soil erosion, and other consequences of unsustainable land management (16). Further losses, which may be exacerbated by climate change, are likely (7). Recent policy decisions to produce first-generation biofuels on good quality agricultural land have added to the competitive pressures (17). Thus, the most likely scenario is that more food will need to be produced from the same amount of (or even less) land. Moreover, there are no major new fishing grounds: Virtually all capture fisheries are fully exploited, and most are overexploited.
Recent studies suggest that the world will need 70 to 100% more food by 2050 (1, 18). In this article, major strategies for contributing to the challenge of feeding 9 billion people, including the most disadvantaged, are explored. Particular emphasis is given to sustainability, as well as to the combined role of the natural and social sciences in analyzing and addressing the challenge.
Closing the Yield Gap
There is wide geographic variation in crop and livestock productivity, even across regions that experience similar climates. The difference between realized productivity and the best that can be achieved using current genetic material and available technologies and management is termed the "yield gap." The best yields that can be obtained locally depend on the capacity of farmers to access and use, among other things, seeds, water, nutrients, pest management, soils, biodiversity, and knowledge. It has been estimated that in those parts of Southeast Asia where irrigation is available, average maximum climate-adjusted rice yields are 8.5 metric tons per hectare, yet the average actually achieved yields are 60% of this figure (19). Similar yield gaps are found in rain-fed wheat in central Asia and rain-fed cereals in Argentina and Brazil. Another way to illustrate the yield gap is to compare changes in per capita food production over the past 50 years. In Asia, this amount has increased approximately twofold (in China, by a factor of nearly 3.5), and in Latin America, it has increased 1.6-fold; in Africa, per capita production fell back from the mid-1970s and has only just reached the same level as in 1961 (2, 20). Substantially more food, as well as theincome to purchase food, could be produced with current crops and livestock if methods were found to close the yield gaps.
Low yields occur because of technical constraints that prevent local food producers from increasing productivity or for economic reasons arising from market conditions. For example, farmers may not have access to the technical knowledge and skills required to increase production, the finances required to invest in higher production (e.g., irrigation, fertilizer, machinery, crop-protection products, and soil-conservation measures), or the crop and livestockvarieties that maximize yields. After harvest or slaughter, they may not be able to store the produce or have access to the infrastructure to transport the produce to consumer markets. Farmers may also choose not to invest in improving agricultural productivity because the returns do not compare well with other uses of capital and labor.
Exactly how best to facilitate increased food production is highly site-specific. In the most extreme cases of failed states and nonfunctioning markets, the solution lies completely outside the food system. Where a functioning state exists, there is a balance to be struck between investing in overall economic growth as a spur to agriculture and focusing on investing in agriculture as a spur to economic growth, though the two are obviously linked in regions, such as sub-Saharan Africa, where agriculture typically makes up 20 to 40% gross domestic product. In some situations, such as low-income food-importing countries, investing purely in generating widespread income growth to allow food purchases from regions and countries with better production capabilities may be the best choice. When investment is targeted at food production, a further issue is the balance between putting resources into regional and national infrastructure, such as roads and ports, and investing in local social and economic capital (21, 22).
A yield gap may also exist because the high costs of inputs or the low returns from increased production make it economically suboptimal to raise production to the maximum technically attainable. Poor transport and market infrastructure raise the prices of inputs, such as fertilizers and water, and increase the costs of moving the food produced into national or world markets. Where the risks of investment are high and the means to offset them are absent, not investing can be the most rational decision, part of the "poverty trap." Food production in developing countries can be severely affected by market interventions in the developed world, such as subsidies or price supports. These need to be carefully designed and implemented so that their effects on global commodity prices do not act as disincentives to production in other countries (23).
The globalization of the food system offers some local food producers access to larger markets, as well as to capital for investment. At the aggregate level, it also appears to increase the global efficiency of food production by allowing regional specialization in the production of the locally most appropriate foods. Because the expansion of food production and the growth of population both occur at different rates in different geographic regions, global trade is necessary to balance supply and demand across regions. However, the environmental costs of food production might increase with globalization, for example, because of increased greenhouse gas emissions associated with increased production and food transport (24). An unfettered market can also penalize particular communities and sectors, especially the poorest who have the least influence on how global markets are structured and regulated. Expanded trade can provide insurance against regional shocks on production such as conflict, epidemics, droughts, or floods—shocks that are likely to increase in frequency as climate change occurs. Conversely, a highly connected foodsystem may lead to the more widespread propagation of economic perturbations, as in the recent banking crisis, thus affecting more people. There is an urgent need for a better understanding of the effects of globalization on the full food system and its externalities.
The yield gap is not static. Maintaining, let alone increasing, productivity depends on continued innovation to control weeds, diseases, insects, and other pests as they evolve resistance to different control measures, or as new species emerge or are dispersed to new regions. Innovation involves both traditional and advanced crop and livestock breeding, as well as the continuing development of better chemical, agronomic, and agro-ecological control measures. The maximum attainable yield in different regions will also shift as the effects of climate change are felt. Increasing atmospheric CO2 levels can directly stimulate crop growth, though within the context of real agricultural production systems, the magnitude of this effect is not clear (7). More important will be the ability to grow crops in places that are currently unsuitable, particularly the northern temperate regions (though expansion of agriculture at the expense of boreal forest would lead to major greenhouse gas emissions), and the loss of currently productive regions because of excessively high temperatures and drought. Models that couple the physics of climate change with the biology of crop growth will be important to help policy-makers anticipate these changes, as well as to evaluate the role of "agricultural biodiversity" in helping mitigate their effects (25).
Closing the yield gap would dramatically increase the supply of food, but with uncertain impacts on the environment and potential feedbacks that could undermine future food production. Food production has important negative "externalities," namely effects on the environment or economy that are not reflected in the cost of food. These include the release of greenhouse gases [especially methane and nitrous oxide, which are more damaging than CO2 and for which agriculture is a major source (26)], environmental pollution due to nutrient run-off, water shortages due to overextraction, soil degradation and the loss of biodiversity through land conversion or inappropriate management, and ecosystem disruption due to the intensive harvesting of fish and other aquatic foods (6).
To address these negative effects, it is now widely recognized that food production systems and the food chain in general must become fully sustainable (18). The principle of sustainability implies the use of resources at rates that do not exceed the capacity of Earth to replace them. By definition, dependency on nonrenewable inputs is unsustainable, even if in the short term it is necessary as part of a trajectory toward sustainability.
There are many difficulties in making sustainability operational. Over what spatial scale should food production be sustainable? Clearly an overarching goal is global sustainability, but should this goal also apply at lower levels, such as regions (or oceans), nations, or farms? Could high levels of consumption or negative externalities in some regions be mitigated by improvements in other areas, or could some unsustainable activities in the food system be offset by actions in the nonfood sector (through carbon-trading, for example)? Though simple definitions of sustainability areindependent of time scale, in practice, how fast should we seek to move from the status quo to a sustainable food system? The challenges of climate change and competition for water, fossil fuels, and other resources suggest that a rapid transition is essential. Nevertheless, it is also legitimate to explore the possibility that superior technologies may become available and that future generations may be wealthier and, hence, better able to absorb the costs of the transition. Finally, we do not yet have good enough metrics of sustainability, a major problem when evaluating alternative strategies and negotiating trade-offs. This is the case for relatively circumscribed activities, such as crop production on individual farms, and even harder when the complete food chain is included or for complex products that may contain ingredients sourced from all around the globe.
There is also a danger that an overemphasis on what can be measured relatively simply (carbon, for example) may lead to dimensions of sustainability that are harder to quantify (such as biodiversity) being ignored. These are areas at the interface of science, engineering, and economics that urgently need more attention (see Box 1). The introduction of measures to promote sustainability does not necessarily reduce yields or profits. One study of 286 agricultural sustainability projects in developing countries,involving 12.6 million chiefly small-holder farmers on 37 million hectares, found an average yield increase of 79% across a very wide variety of systems and crop types (27). One-quarter of the projects reported a doubling of yield. Research on the ability of these and related programs to be scaled up to country and regional levels should be a priority (Fig. 2).
Strategies designed to close the yield gap in the poorest countries face some particular challenges (28). Much production is dominated by small-holder agriculture with women often taking a dominant role in the workforce. Where viable, investment in the socialand economic mechanisms to enable improved small-holder yields, especially where targeted at women, can be important means of increasing the income of both farm and rural nonfarm households. The lack of secure land rights can be a particular problem formany poor communities, may act as a disincentive for small holders to invest in managing the land more productively, and may make it harder to raise investment capital (29). In a time of rising prices for food and land, it can also render these communities vulnerable to displacement by more powerful interest groups. Where the political will and organizational infrastructure exist, title definition and protection could be greatly assisted by the application of modern information and communication technologies. Even so, there will be many people who cannot afford to purchase sufficient calories and nutrients for a healthy life and who will require social protection programs to increase their ability to obtain food. However, if properly designed, these programs can help stimulate local agriculture by providing small holders with increased certainty about the demand for their products.
There is also a role for large-scale farming operations in poor-country agriculture, though the value and contexts in which this is feasible are much debated (30). This debate has been fanned by a substantial increase in the number of sovereign wealth funds, companies, and individuals leasing, purchasing, or attempting to purchase large tracts of agricultural land in developing countries. This external investment in developing-country agriculture may bring major benefits, especially where investors bring considerable improvements to crop production and processing, but only if the rights and welfare of the tenants and existing resource users are properly addressed (31).
Many of the very poorest people live in areas so remote that they are effectively disconnected from national and world food markets. But for others, especially the urban poor, higher food prices have a direct negative effect on their ability to purchase a healthy diet. Many rural farmers and other food producers live near the margin of being net food consumers and producers and will be affected in complex ways by rising food prices, with some benefitting and some being harmed (21). Thus, whereas reducing distorting agricultural support mechanisms in developed countries and liberalizing world trade should stimulate overall food production in developing countries, not everyone will gain (23, 32). Better models that can more accurately predict these complex interactions are urgently needed.
References and Notes
1. World Bank, World Development Report 2008: Agriculture for Development (World Bank, Washington, DC, 2008).
2. FAOSTAT, http://faostat.fao.org/default.aspx (2009).
3. Food and Agriculture Organization of the United Nations (FAO), State of Food Insecurity in the World 2009 (FAO, Rome, 2009).
4. A. Evans, The Feeding of the Nine Billion: Global Food Security (Chatham House, London, 2009).
5. D. Tilman et al., Forecasting agriculturally driven global environmental change. Science 292, 281 (2001).[Abstract/Free Full Text]
6. Millenium Ecosystem Assessment, Ecosystems and Human Well-Being (World Resources Institute, Washington, DC, 2005).
7. Intergovernmental Panel on Climate Change, Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M. L. Parry et al., Eds. (Cambridge Univ. Press, Cambridge, 2007).
8. J. Schmidhuber, F. N. Tubiello, Global food security under climate change. Proc. Natl. Acad. Sci. U.S.A. 104, 19703 (2007). [Abstract/Free Full Text]
9. J. von Braun, The World Food Situation: New Driving Forces and Required Actions (International Food Policy Research Institute, Washington, DC, 2007).
10. G. Conway, The Doubly Green Revolution (Penguin Books, London, 1997).
11. J. Piesse, C. Thirtle, Three bubbles and a panic: An explanatory review of recent food commodity price events.Food Policy 34, 119 (2009). [CrossRef] [Web of Science]
12. Royal Society of London, Sustainable Biofuels: Prospects and Challenges (Royal Society, London, 2008).
13. R. Skidelsky, The Return of the Master (Allen Lane, London, 2009).
14. J. Pretty, Agricultural sustainability: Concepts, principles and evidence. Philos. Trans. R. Soc. London Ser. B Biol. Sci. 363, 447 (2008). [Abstract/Free Full Text]
15. A. Balmford, R. E. Green, J. P. W. Scharlemann, Sparing land for nature: exploring the potential impact of changes in agricultural yield on the area needed for crop production. Global Change Biol. 11, 1594 (2005).[CrossRef]
16. C. Nellemann et al., Eds., The Environmental Food Crisis [United Nations Environment Programme (UNEP), Nairobi, Kenya, 2009].
17. J. Fargione, J. Hill, D. Tilman, S. Polasky, P. Hawthorne, Land clearing and the biofuel carbon debt. Science 319, 1235 (2008); published online 7 February 2008 (10.1126/science.1152747). [Abstract/Free Full Text]
18. Royal Society of London, Reaping the Benefits: Science and the Sustainable Intensification of Global Agriculture(Royal Society, London, 2009).
19. K. G. Cassman, Ecological intensification of cereal production systems: Yield potential, soil quality, and precision agriculture. Proc. Natl. Acad. Sci. U.S.A. 96, 5952 (1999). [Abstract/Free Full Text]
20. R. E. Evenson, D. Gollin, Assessing the impact of the Green Revolution, 1960 to 2000. Science 300, 758 (2003).[Abstract/Free Full Text]
21. P. Hazell, L. Haddad, Food Agriculture and the Environment Discussion Paper 34, (International Food Policy Research Institute, Washington, DC, 2001).
22. Forum for Agricultural Research in Africa, Framework for African Agricultural Productivity (Forum for Agricultural Research in Africa, Accra, Ghana, 2006).
23. K. Anderson, Ed., Distortions to Agricultural Incentives, a Global Perspective 1955-2007 (Palgrave Macmillan, London, 2009).
24. J. N. Pretty, A. S. Ball, T. Lang, J. I. L. Morison, Farm costs and food miles: An assessment of the full cost of the UK weekly food basket. Food Policy 30, 1 (2005). [CrossRef] [Web of Science]
25. G. C. Nelson et al., Climate Change: Impact on Agriculture and Costs of Adaptation (International Food Policy Research Institute, Washington, DC, 2009).
26. N. Stern, The Economics of Climate Change (Cambridge Univ. Press, Cambridge, 2007).
27. J. N. Pretty et al., Resource-conserving agriculture increases yields in developing countries. Environ. Sci. Technol. 40, 1114 (2006). [Medline]
28. P. Hazell, S. Wood, Drivers of change in global agriculture. Philos. Trans. R. Soc. London Ser. B Biol. Sci. 363, 495 (2008). [Abstract/Free Full Text]
29. K. Deininger, G. Feder, Land registration, governance, and development: Evidence and implications for policy.World Bank Res. Obs. 24, 233 (2009). [Abstract/Free Full Text]
30. P. Collier, The politics of hunger: How illusion and greed fan the food crisis. Foreign Aff. 87, 67 (2008).[Web of Science]
31. L. Cotula, S. Vermeulen, L. Leonard, J. Keeley, Land Grab or Development Opportunity? Agricultural Investment and International Land Deals in Africa [International Institute for Environment and Development (with FAO and International Fund for Agricultural Development), London, 2009].
32. A. Aksoy, J. C. Beghin, Eds., Global Agricultural Trade and Developing Countries (World Bank, Washington, DC, 2005).