Food Security

Food Security: The Challenge of Feeding 9 Billion People H. Charles J. Godfray, et al. Science 327, 812 (2010); DOI: 10.1126/science.1185383
This copy is for your personal, non-commercial use only.

If you wish to distribute this article to others, you can order high-quality copies for your colleagues, clients, or customers by clicking here. Permission to republish or repurpose articles or portions of articles can be obtained by following the guidelines here. The following resources related to this article are available online at www.sciencemag.org (this information is current as of August 20, 2010 ): Updated information and services, including high-resolution figures, can be found in the online version of this article at: http://www.sciencemag.org/cgi/content/full/327/5967/812 A list of selected additional articles on the Science Web sites related to this article can be found at: http://www.sciencemag.org/cgi/content/full/327/5967/812#related-content This article cites 21 articles, 11 of which can be accessed for free: http://www.sciencemag.org/cgi/content/full/327/5967/812#otherarticles This article has been cited by 4 article(s) on the ISI Web of Science. This article has been cited by 5 articles hosted by HighWire Press; see: http://www.sciencemag.org/cgi/content/full/327/5967/812#otherarticles This article appears in the following subject collections: Ecology http://www.sciencemag.org/cgi/collection/ecology

Science (print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by the American Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. Copyright 2010 by the American Association for the Advancement of Science; all rights reserved. The title Science is a registered trademark of AAAS.

Downloaded from www.sciencemag.org on August 20, 2010

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 H. Charles J. Godfray,1* John R. Beddington,2 Ian R. Crute,3 Lawrence Haddad,4 David Lawrence,5 trends in the availability of food, at least for those who can afford it and have access to world marJames F. Muir,6 Jules Pretty,7 Sherman Robinson,8 Sandy M. Thomas,9 Camilla Toulmin10 kets. Over the past century, gross food prices have generally fallen, leveling off in the past three decContinuing 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, in addition to ades but punctuated by price spikes such as that the overexploitation of fisheries, will affect our ability to produce food, as will the urgent requirement caused by the 1970s oil crisis. In mid-2008, there was an unexpected rapid rise in food prices, the 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 cause of which is still being debated, that subsided equitably. A multifaceted and linked global strategy is needed to ensure sustainable and equitable food when the world economy went into recession (11). However, many (but not all) commentators have security, different components of which are explored here. predicted that this spike heralds a period of rising he past half-century has seen marked from a larger and more affluent population to its and more volatile food prices driven primarily by growth in food production, allowing for a supply; do so in ways that are environmentally increased demand from rapidly developing coundramatic decrease in the proportion of the and socially sustainable; and ensure that the tries, as well as by competition for resources from world’s people that are hungry, despite a doubling world’s poorest people are no longer hungry. first-generation biofuels production (12). Increased of the total population (Fig. 1) (1, 2). Neverthe- This challenge requires changes in the way food food prices will stimulate greater investment in less, more than one in seven people today still do is produced, stored, processed, distributed, and food production, but the critical importance of food not have access to sufficient protein and energy accessed that are as radical as those that occurred to human well-being and also to social and political stability makes it likely that from their diet, and even more suffer from some governments and other organizations form of micronutrient malnourishment (3). The A Main grains (wheat, barley, 3.5 will want to encourage food proworld is now facing a new set of intersecting chalmaize, rice, oats) duction beyond that driven by simlenges (4). The global population will continue to Coarse grains 3.0 ple market mechanisms (13). The grow, yet it is likely to plateau at some 9 billion (millet, sorghum) long-term nature of returns on inpeople by roughly the middle of this century. A Root crops (cassava, potato) 2.5 vestment for many aspects of food major correlate of this deceleration in population production and the importance of growth is increased wealth, and with higher purpolicies that promote sustainability chasing power comes higher consumption and a 2.0 and equity also argue against purely greater demand for processed food, meat, dairy, relying on market solutions. and fish, all of which add pressure to the food 1.5 So how can more food be prosupply system. At the same time, food producers duced sustainably? In the past, the are experiencing greater competition for land, 1.0 primary solution to food shortages water, and energy, and the need to curb the many has been to bring more land into negative effects of food production on the envi0.5 agriculture and to exploit new fish ronment is becoming increasingly clear (5, 6). 1960 1970 1980 1990 2000 2010 stocks. Yet over the past 5 decades, Overarching all of these issues is the threat of the while grain production has more effects of substantial climate change and concerns B 5.0 than doubled, the amount of land about how mitigation and adaptation measures Chickens devoted to arable agriculture globalmay affect the food system (7, 8). 4.5 Pigs Cattle and buffalo ly has increased by only ~9% (14). A threefold challenge now faces the world (9): 4.0 Sheep and goats Some new land could be brought Match the rapidly changing demand for food 3.5 into cultivation, but the competi1 Department of Zoology and Institute of Biodiversity at the 3.0 tion for land from other human acJames Martin 21st Century School, University of Oxford, South tivities makes this an increasingly 2.5 Parks Road, Oxford OX1 3PS, UK. 2U.K. Government Office for unlikely and costly solution, parScience, 1 Victoria Street, London SW1H OET, UK. 3Agricul2.0 ticularly if protecting biodiversity ture and Horticulture Development Board, Stoneleigh Park, Kenilworth, Warwickshire CV8 2TL, UK. 4Institute of Develop1.5 and the public goods provided by ment Studies, Falmer, Brighton BN1 9RE, UK. 5Syngenta AG, natural ecosystems (for example, 6 1.0 Post Office Box, CH-4002 Basel, Switzerland. Institute of Aquacarbon storage in rainforest) are culture, University of Stirling, Stirling FK9 4LA, UK. 7Department 0.5 given higher priority (15). In recent of Biological Sciences, University of Essex, Wivenhoe Park, 1960 1970 1980 1990 2000 2010 Colchester, Essex CO4 3SQ, UK. 8Institute of Development decades, agricultural land that was 9 Studies, Falmer, Brighton BN1 9RE, UK. Foresight, U.K. Govformerly productive has been lost ernment Office for Science, 1 Victoria Street, London SW1H Fig. 1. Changes in the relative global production of crops and to urbanization and other human OET, UK. 10International Institute for Environment and Developanimals since 1961 (when relative production scaled to 1 in uses, as well as to desertification, ment, 3 Endsleigh Street, London WC1H 0DD, UK. 1961). (A) Major crop plants and (B) major types of livestock. salinization, soil erosion, and other *To whom correspondence should be addressed. E-mail: [Source: (2)] consequences of unsustainable land [email protected]
REVIEW

Food Security: The Challenge of Feeding 9 Billion People

T

812

12 FEBRUARY 2010

Relative numbers

VOL 327

SCIENCE

www.sciencemag.org

Downloaded from www.sciencemag.org on August 20, 2010

Relative production

SPECIALSECTION
A yield gap may also exist because the high management (16). Further losses, which may increasing productivity or for economic reasons be exacerbated by climate change, are likely arising from market conditions. For example, costs of inputs or the low returns from increased (7). Recent policy decisions to produce first- farmers may not have access to the technical production make it economically suboptimal to generation biofuels on good quality agricultural knowledge and skills required to increase pro- raise production to the maximum technically atland have added to the competitive pressures duction, the finances required to invest in higher tainable. Poor transport and market infrastruc(17). Thus, the most likely scenario is that more production (e.g., irrigation, fertilizer, machinery, ture raise the prices of inputs, such as fertilizers food will need to be produced from the same crop-protection products, and soil-conservation and water, and increase the costs of moving the amount of (or even less) land. Moreover, there measures), or the crop and livestock varieties food produced into national or world markets. are no major new fishing grounds: Virtually all that maximize yields. After harvest or slaughter, Where the risks of investment are high and the capture fisheries are fully exploited, and most they may not be able to store the produce or means to offset them are absent, not investing have access to the infrastructure to transport the can be the most rational decision, part of the are overexploited. Recent studies suggest that the world will produce to consumer markets. Farmers may also “poverty trap.” Food production in developing need 70 to 100% more food by 2050 (1, 18). In choose not to invest in improving agricultural countries can be severely affected by market interventions in the developed this article, major strategies world, such as subsidies or price for contributing to the chalsupports. These need to be carelenge of feeding 9 billion Box 1. Sustainable intensification. fully designed and implemented people, including the most so that their effects on global disadvantaged, are explored. Producing more food from the same area of land while reducing the environmental commodity prices do not act as Particular emphasis is given impacts requires what has been called “sustainable intensification” (18). In exactly the disincentives to production in to sustainability, as well as same way that yields can be increased with the use of existing technologies, many other countries (23). to the combined role of the options currently exist to reduce negative externalities (47). Net reductions in some The globalization of the natural and social sciences greenhouse gas emissions can potentially be achieved by changing agronomic food system offers some local in analyzing and addressing practices, the adoption of integrated pest management methods, the integrated food producers access to larger the challenge. management of waste in livestock production, and the use of agroforestry. However, markets, as well as to capital the effects of different agronomic practices on the full range of greenhouse gases can Closing the Yield Gap for investment. At the aggrebe very complex and may depend on the temporal and spatial scale of measurement. gate level, it also appears to There is wide geographic varMore research is required to allow a better assessment of competing policy options. increase the global efficiency iation in crop and livestock Strategies such as zero or reduced tillage (the reduction in inversion ploughing), of food production by allowing productivity, even across recontour farming, mulches, and cover crops improve water and soil conservation, but regional specialization in the gions that experience similar they may not increase stocks of soil carbon or reduce emissions of nitrous oxide. production of the locally most climates. The difference bePrecision agriculture refers to a series of technologies that allow the application of appropriate foods. Because the tween realized productivity water, nutrients, and pesticides only to the places and at the times they are required, expansion of food production and the best that can be thereby optimizing the use of inputs (48). Finally, agricultural land and water bodies and the growth of population achieved using current geused for aquaculture and fisheries can be managed in ways specifically designed to both occur at different rates in netic material and available reduce negative impacts on biodiversity. different geographic regions, technologies and manageglobal trade is necessary to bament is termed the “yield lance supply and demand across gap.” The best yields that can be obtained locally depend on the capacity productivity because the returns do not compare regions. However, the environmental costs of food production might increase with globalizaof farmers to access and use, among other things, well with other uses of capital and labor. Exactly how best to facilitate increased food tion, for example, because of increased greenhouse seeds, water, nutrients, pest management, soils, biodiversity, and knowledge. It has been esti- production is highly site-specific. In the most gas emissions associated with increased producmated that in those parts of Southeast Asia extreme cases of failed states and nonfunction- tion and food transport (24). An unfettered marwhere irrigation is available, average maximum ing markets, the solution lies completely out- ket can also penalize particular communities and climate-adjusted rice yields are 8.5 metric tons side the food system. Where a functioning state sectors, especially the poorest who have the least per hectare, yet the average actually achieved exists, there is a balance to be struck between influence on how global markets are structured yields are 60% of this figure (19). Similar yield investing in overall economic growth as a spur and regulated. Expanded trade can provide insurgaps are found in rain-fed wheat in central Asia to agriculture and focusing on investing in ag- ance against regional shocks on production such and rain-fed cereals in Argentina and Brazil. riculture as a spur to economic growth, though as conflict, epidemics, droughts, or floods—shocks Another way to illustrate the yield gap is to the two are obviously linked in regions, such as that are likely to increase in frequency as climate compare changes in per capita food production sub-Saharan Africa, where agriculture typically change occurs. Conversely, a highly connected over the past 50 years. In Asia, this amount has makes up 20 to 40% gross domestic product. food system may lead to the more widespread increased approximately twofold (in China, by a In some situations, such as low-income food- propagation of economic perturbations, as in the factor of nearly 3.5), and in Latin America, it has importing countries, investing purely in generat- recent banking crisis, thus affecting more peoincreased 1.6-fold; in Africa, per capita produc- ing widespread income growth to allow food ple. There is an urgent need for a better undertion fell back from the mid-1970s and has only purchases from regions and countries with bet- standing of the effects of globalization on the just reached the same level as in 1961 (2, 20). ter production capabilities may be the best full food system and its externalities. The yield gap is not static. Maintaining, let Substantially more food, as well as the income to choice. When investment is targeted at food purchase food, could be produced with current production, a further issue is the balance be- alone increasing, productivity depends on concrops and livestock if methods were found to tween putting resources into regional and na- tinued innovation to control weeds, diseases, inclose the yield gaps. tional infrastructure, such as roads and ports, sects, and other pests as they evolve resistance Low yields occur because of technical con- and investing in local social and economic to different control measures, or as new species emerge or are dispersed to new regions. straints that prevent local food producers from capital (21, 22). www.sciencemag.org SCIENCE VOL 327 12 FEBRUARY 2010

813

Downloaded from www.sciencemag.org on August 20, 2010

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 are independent 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

search 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 social and economic mechanisms to enable improved small-holder yields,

Fig. 2. An example of a major successful sustainable agriculture project. Niger was strongly affected by a series of drought years in the 1970s and 1980s and by environmental degradation. From the early 1980s, donors invested substantially in soil and water conservation. The total area treated is on the order of 300,000 ha, most of which went into the rehabilitation of degraded land. The project in the Illela district of Niger promoted simple water-harvesting techniques. Contour stone bunds, half moons, stone bunding, and improved traditional planting pits (zaı¨) were used to rehabilitate barren, crusted land. More than 300,000 ha have been rehabilitated, and crop yields have increased and become more stable from year to year. Tree cover has increased, as shown in the photographs. Development of the land market and continued incremental expansion of the treated area without further project assistance indicate that the outcomes are sustainable (51, 52). 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 smallholder 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. ReVOL 327 SCIENCE 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 for many 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.

814

12 FEBRUARY 2010

www.sciencemag.org

Downloaded from www.sciencemag.org on August 20, 2010

SPECIALSECTION
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 developingcountry 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. Increasing Production Limits The most productive crops, such as sugar cane, growing in optimum conditions, can convert solar energy into biomass with an efficiency of ~2%, resulting in high yields of biomass (up to 150 metric tons per hectare) (33). There is much debate over exactly what the theoretical limits are for the major crops under different conditions, and similarly, for the maximum yield that can be obtained for livestock rearing (18). However, there is clearly considerable scope for increasing production limits. The Green Revolution succeeded by using conventional breeding to develop F1 hybrid varieties of maize and semi-dwarf, disease-resistant varieties of wheat and rice. These varieties could be provided with more irrigation and fertilizer (20) without the risk of major crop losses due to lodging (falling over) or severe rust epidemics. Increased yield is still a major goal, but the importance of greater water- and nutrient-use efficiency, as well as tolerance of abiotic stress, is also likely to increase. Modern genetic techniques and a better understanding of crop physiology allow for a more directed approach to selection across multiple traits. The speed and costs at which genomes today can be sequenced or resequenced now means that these techniques can be more easily applied to develop varieties of crop species that will yield well in challenging environments. Table 1. Examples of current and potential future applications of GM technology for crop genetic improvement. [Source: (18, 49)]
Time scale Current Target crop trait Tolerance to broad-spectrum herbicide Resistance to chewing insect pests Nutritional bio-fortification Resistance to fungus and virus pathogens Resistance to sucking insect pests Improved processing and storage Drought tolerance Salinity tolerance Increased nitrogen-use efficiency High-temperature tolerance apomixis Nitrogen fixation Denitrification inhibitor production Conversion to perennial habit Increased photosynthetic efficiency Target crops Maize, soybean, oilseed brassica Maize, cotton, oilseed brassica Staple cereal crops, sweet potato Potato, wheat, rice, banana, fruits, vegetables Rice, fruits, vegetables Wheat, potato, fruits, vegetables Staple cereal and tuber crops Staple cereal and tuber crops

Short-term (5–10 years)

Medium-term (10–20 years)

Long-term (>20 years)

Staple cereal and tuber crops

These include crops such as sorghum, millet, cassava, and banana, species that are staple foods for many of the world’s poorest communities (34). Currently, the major commercialized genetically modified (GM) crops involve relatively simple manipulations, such as the insertion of a gene for herbicide resistance or another for a pest-insect toxin. The next decade will see the development of combinations of desirable traits and the introduction of new traits such as drought tolerance. By mid-century, much more radical options involving highly polygenic traits may be feasible (Table 1). Production of cloned animals with engineered innate immunity to diseases that reduce production efficiency has the potential to reduce substantial losses arising from mortality and subclinical infections. Biotechnology could also produce plants for animal feed with modified composition that increase the efficiency of meat production and lower methane emissions. Domestication inevitably means that only a subset of the genes available in the wild-species progenitor gene pool is represented among crop varieties and livestock breeds. Unexploited genetic material from land races, rare breeds, and wild relatives will be important in allowing breeders to respond to new challenges. International collections and gene banks provide valuable repositories for such genetic variation, but it is nevertheless necessary to ensure that locally adapted crop and livestock germplasm is not lost in the process of their displacement by modern, improved varieties and breeds. The trend over recent decades is of a general decline in investment in technological innovation in food producSCIENCE VOL 327

tion (with some notable exceptions, such as in China and Brazil) and a switch from public to private sources (1). Fair returns on investment are essential for the proper functioning of the private sector, but the extension of the protection of intellectual property rights to biotechnology has led to a growing public perception in some countries that biotech research purely benefits commercial interests and offers no long-term public good. Just as seriously, it also led to a virtual monopoly of GM traits in some parts of the world, by a restricted number of companies, which limits innovation and investment in the technology. Finding ways to incentivize wide access and sustainability, while encouraging a competitive and innovative private sector to make best use of developing technology, is a major governance challenge. The issue of trust and public acceptance of biotechnology has been highlighted by the debate over the acceptance of GM technologies. Because genetic modification involves germline modification of an organism and its introduction to the environment and food chain, a number of particular environmental and food safety issues need to be assessed. Despite the introduction of rigorous science-based risk assessment, this discussion has become highly politicized and polarized in some countries, particularly those in Europe. Our view is that genetic modification is a potentially valuable technology whose advantages and disadvantages need to be considered rigorously on an evidential, inclusive, case-by-case basis: Genetic modification should neither be privileged nor automatically dismissed. We also accept the

www.sciencemag.org

12 FEBRUARY 2010

815

Downloaded from www.sciencemag.org on August 20, 2010

Retail

Food Service

Home and municipal

Reducing Waste Roughly 30 to 40% of food in both Fig. 3. Makeup of total food waste in developed and developthe developed and developing worlds ing countries. Retail, food service, and home and municipal is lost to waste, though the causes categories are lumped together for developing countries. behind this are very different (Fig. 3) [Source: (16, 37–39)] (16, 37–39). In the developing world, Different strategies are required to tackle the losses are mainly attributable to the absence of food-chain infrastructure and the lack of knowl- two types of waste. In developing countries, pubedge or investment in storage technologies on lic investment in transport infrastructure would the farm, although data are scarce. For example, reduce the opportunities for spoilage, whereas in India, it is estimated that 35 to 40% of fresh better-functioning markets and the availability produce is lost because neither wholesale nor of capital would increase the efficiency of the retail outlets have cold storage (16). Even with food chain, for example, by allowing the introrice grain, which can be stored more readily, as duction of cold storage (though this has implicamuch as one-third of the harvest in Southeast tions for greenhouse gas emissions) (38). Existing Asia can be lost after harvest to pests and spoil- technologies and best practices need to be spread age (40). But the picture is more complex than by education and extension services, and market a simple lack of storage facilities: Although and finance mechanisms are required to protect storage after harvest when there is a glut of farmers from having to sell at peak supply, leadfood would seem to make economic sense, the ing to gluts and wastage. There is also a need for farmer often has to sell immediately to raise continuing research in postharvest storage technologies. Improved technology for small-scale cash. In contrast, in the developed world, pre-retail food storage in poorer contexts is a prime canlosses are much lower, but those arising at the didate for the introduction of state incentives for retail, food service, and home stages of the food private innovation, with the involvement of smallchain have grown dramatically in recent years, scale traders, millers, and producers. If food prices were to rise again, it is likely for a variety of reasons (41). At present, food is relatively cheap, at least for these consumers, that there would be a decrease in the volume of which reduces the incentives to avoid waste. Con- waste produced by consumers in developed counsumers have become accustomed to purchasing tries. Waste may also be reduced by alerting confoods of the highest cosmetic standards; hence, sumers to the scale of the issue, as well as to retailers discard many edible, yet only slightly domestic strategies for reducing food loss. Ad-

816

12 FEBRUARY 2010

VOL 327

SCIENCE

www.sciencemag.org

Downloaded from www.sciencemag.org on August 20, 2010

need for this technology to gain greater public blemished products. Commercial pressures can acceptance and trust before it can be considered encourage waste: The food service industry freas one among a set of technologies that may quently uses “super-sized” portions as a competitive lever, whereas “buy one get one free” offers contribute to improved global food security. There are particular issues involving new have the same function for retailers. Litigation technologies, both GM and non-GM, that are and lack of education on food safety have lead targeted at helping the least-developed countries to a reliance on “use by” dates, whose safety (35, 36). The technologies must be directed at margins often mean that food fit for consumpthe needs of those communities, which are often tion is thrown away. In some developed different from those of more developed country countries, unwanted food goes to a landfill farmers. To increase the likelihood that new tech- instead of being used as animal feed or compost nology works for, and is adopted by, the poorest because of legislation to control prion diseases. nations, they need to be involved in the framing, prioritization, risk assessment, and regulation of innovations. This will often require the Developing creation of innovative institutional countries and governance mechanisms that account for socio-cultural context (for example, the importance of women in developing-country food producUSA tion). New technologies offer major promise, but there are risks of lost trust if their potential benefits are exaggerated in public debate. Efforts UK to increase sustainable production limits that benefit the poorest nations 0% 50% 100% will need to be based around new alliances of businesses, civil society On-farm Transport and processing organizations, and governments.

vocacy, education, and possibly legislation may also reduce waste in the food service and retail sectors. Legislation such as that on sell-by dates and swill that has inadvertently increased food waste should be reexamined within a more inclusive competing-risks framework. Reducing developed-country food waste is particularly challenging, as it is so closely linked to individual behavior and cultural attitudes toward food. Changing Diets The conversion efficiency of plant into animal matter is ~10%; thus, there is a prima facie case that more people could be supported from the same amount of land if they were vegetarians. About one-third of global cereal production is fed to animals (42). But currently, one of the major challenges to the food system is the rapidly increasing demand for meat and dairy products that has led, over the past 50 years, to a ~1.5-fold increase in the global numbers of cattle, sheep, and goats, with equivalent increases of ~2.5- and ~4.5-fold for pigs and chickens, respectively (2) (Fig. 1). This is largely attributable to the increased wealth of consumers everywhere and most recently in countries such as China and India. However, the argument that all meat consumption is bad is overly simplistic. First, there is substantial variation in the production efficiency and environmental impact of the major classes of meat consumed by people (Table 2). Second, although a substantial fraction of livestock is fed on grain and other plant protein that could feed humans, there remains a very substantial proportion that is grass-fed. Much of the grassland that is used to feed these animals could not be converted to arable land or could only be converted with majorly adverse environmental outcomes. In addition, pigs and poultry are often fed on human food “waste.” Third, through better rearing or improved breeds, it may be possible to increase the efficiency with which meat is produced. Finally, in developing countries, meat represents the most concentrated source of some vitamins and minerals, which is important for individuals such as young children. Livestock also are used for ploughing and transport, provide a local supply of manure, can be a vital source of income, and are of huge cultural importance for many poorer communities. Reducing the consumption of meat and increasing the proportion that is derived from the most efficient sources offer an opportunity to feed more people and also present other advantages (37). Well-balanced diets rich in grains and other vegetable products are considered to be more healthful than those containing a high proportion of meat (especially red meat) and dairy products. As developing countries consume more meat in combination with high-sugar and -fat foods, they may find themselves having to deal with obesity before they have overcome undernutrition, leading to an increase in spending on health that could

SPECIALSECTION
Table 2. Comparison of the impact of grazing and intensive (confined/industrialized) grain-fed livestock systems on water use, grain requirement, and methane production. Service water is that required for cleaning and washing livestock housing and other facilities. Dashes indicate combinations for which no data are available (either because it cannot be measured or because the combination does not exist). This table does not include other impacts of differing livestock management systems such as (i) nutrient run-off and pollution to surface and groundwater, (ii) protozoan and bacterial contamination of water and food, (iii) antibiotic residues in water and food, (iv) heavy metal from feed in soils and water, (v) odor nuisance from wastes, (vi) inputs used for feed production and lost to the environment, (vii) livestock-related land-use change. [Source: (7, 50)]
Water Measure of water use Grazing Intensive Liters day–1 per animal at 15°C Drinking water: all Service water: beef Service water: dairy Pigs (lactating adult) Drinking water Service water Sheep (lactating adult) Drinking water Service water Chicken (broiler and layer) Drinking water Service water Feed required to produce 1 kg of meat Cattle Pigs Chicken (broiler) Methane emissions from cattle Cattle: dairy (U.S., Europe) Cattle: beef, dairy (U.S., Europe) Cattle: dairy (Africa, India) Cattle: grazing (Africa, India) Cattle 22 103 5 11 5 22 17 17 25 125 9 9 5 5 1.3–1.8 1.3–1.8 0.09–0.15 0.09–0.15 kg of cereal per animal – 8 – 4 – 1 kg of CH4 per animal year–1 – 117–128 53–60 – – 45–58 27–31 –

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., Science 292, 281 (2001). 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, Proc. Natl. Acad. Sci. U.S.A. 104, 19703 (2007). 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, Food Policy 34, 119 (2009). 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, Philos. Trans. R. Soc. London Ser. B Biol. Sci. 363, 447 (2008). 15. A. Balmford, R. E. Green, J. P. W. Scharlemann, Global Change Biol. 11, 1594 (2005). 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, Science 319, 1235 (2008); published online 7 February 2008 (10.1126/science.1152747). 18. Royal Society of London, Reaping the Benefits: Science and the Sustainable Intensification of Global Agriculture (Royal Society, London, 2009). 19. K. G. Cassman, Proc. Natl. Acad. Sci. U.S.A. 96, 5952 (1999). 20. R. E. Evenson, D. Gollin, Science 300, 758 (2003). 21. P. Hazell, L. Haddad, Food Agriculture and the Environment Discussion Paper 34, (International Food Policy Research Institute, Washington, DC, 2001).

otherwise be used to alleviate poverty. Livestock production is also a major source of methane, a very powerful greenhouse gas, though this can be partially offset by the use of animal manure to replace synthetic nitrogen fertilizer (43). Of the five strategies we discuss here, assessing the value of decreasing the fraction of meat in our diets is the most difficult and needs to be better understood. Expanding Aquaculture Aquatic products (mainly fish, aquatic molluscs, and crustaceans) have a critical role in the food system, providing nearly 3 billion people with at least 15% of their animal protein intake (44). In many regions, aquaculture has been sufficiently profitable to permit strong growth; replicating this growth in areas such as Africa where it has not occurred could bring major benefits. Technical advances in hatchery systems, feeds and feed-delivery systems, and disease management could all increase output. Future gains may also come from better stock selection, largerscale production technologies, aquaculture in open seas and larger inland water bodies, and the culture of a wider range of species. The long production cycle of many species (typically 6 to 24 months) requires a financing system that is capable of providing working capital as well as offsetting risk. Wider production options (such as temperature and salinity tolerance and disease resistance) and cheaper feed substrates (for in-

stance, plant material with enhanced nutritional features) might also be accessed with the use of GM technologies. Aquaculture may cause harm to the environment because of the release into water bodies of organic effluents or disease treatment chemicals, indirectly through its dependence on industrial fisheries to supply feeds, and by acting as a source of diseases or genetic contamination for wild species. Efforts to reduce these negative externalities and increase the efficiency of resource use [such as the fish in–to–fish out ratio (45)] have been spurred by the rise of sustainability certification programs, though these mainly affect only higher-value sectors. Gains in sustainability could come from concentrating on lower– trophic level species and in integrating aquatic and terrestrial food production, for example, by using waste from the land as food and nutrients. It will also be important to take a more strategic approach to site location and capacity within catchment or coastal zone management units (46). Conclusions There is no simple solution to sustainably feeding 9 billion people, especially as many become increasingly better off and converge on richcountry consumption patterns. A broad range of options, including those we have discussed here, needs to be pursued simultaneously. We are hopeful about scientific and technological innoSCIENCE VOL 327

www.sciencemag.org

12 FEBRUARY 2010

817

Downloaded from www.sciencemag.org on August 20, 2010

vation in the food system, but not as an excuse to delay difficult decisions today. Any optimism must be tempered by the enormous challenges of making food production sustainable while controlling greenhouse gas emission and conserving dwindling water supplies, as well as meeting the Millennium Development Goal of ending hunger. Moreover, we must avoid the temptation to further sacrifice Earth’s already hugely depleted biodiversity for easy gains in food production, not only because biodiversity provides many of the public goods on which mankind relies but also because we do not have the right to deprive future generations of its economic and cultural benefits. Together, these challenges amount to a perfect storm. Navigating the storm will require a revolution in the social and natural sciences concerned with food production, as well as a breaking down of barriers between fields. The goal is no longer simply to maximize productivity, but to optimize across a far more complex landscape of production, environmental, and social justice outcomes.

10.1126/science.1185383

REVIEW

more so given the additional pressures created by global environmental changes. Global Environmental Change Alters Breeding Targets Certain aspects of global environmental change are beneficial to agriculture. Rising CO2 acts as a fertilizer for C3 crops and is estimated to account for approximately 0.3% of the observed 1% rise in global wheat production (4), although this benefit is likely to diminish, because rising temperatures will increase photorespiration and nighttime respiration. A benefit of rising temperatures is the alleviation of low-temperature inhibition of growth, which is a widespread limitation at higher latitudes and altitudes. Offsetting these benefits, however, are obvious deleterious changes, such as an increased frequency of damaging high-temperature events, new pest and disease pressures, and altered patterns of drought. Negative effects of other pollutants, notably ozone, will also reduce benefits to plant growth from rising CO2 and temperature. Particularly challenging for society will be changes in weather patterns that will require alterations in farming practices and infrastructure; for example, water storage and transport networks. Because one-third of the world’s food is produced on irrigated land (5, 6), the likely impacts on global food production are many. Along with agronomic- and management-based approaches to improving food production, improvements in a crop’s ability to maintain yields with lower water supply and quality will be critical. Put simply, we need to increase the tolerance of crops to drought and salinity. In the context of global environmental change, the efficiency of nitrogen use has also emerged as a key target. Human activity has already more than doubled the amount of atmospheric N2 fixed

Breeding Technologies to Increase Crop Production in a Changing World
Mark Tester* and Peter Langridge To feed the several billion people living on this planet, the production of high-quality food must increase with reduced inputs, but this accomplishment will be particularly challenging in the face of global environmental change. Plant breeders need to focus on traits with the greatest potential to increase yield. Hence, new technologies must be developed to accelerate breeding through improving genotyping and phenotyping methods and by increasing the available genetic diversity in breeding germplasm. The most gain will come from delivering these technologies in developing countries, but the technologies will have to be economically accessible and readily disseminated. Crop improvement through breeding brings immense value relative to investment and offers an effective approach to improving food security. lthough more food is needed for the rapidly growing human population, food quality also needs to be improved, particularly for increased nutrient content. In addition, agricultural inputs must be reduced, especially those of nitrogenous fertilizers, if we are to reduce environmental degradation caused by emissions of CO2 and nitrogenous compounds from agricultural processes. Furthermore, there are now concerns about our ability to increase or even sustain crop yield and quality in the face of dynamic environmental and biotic threats that will be particularly challenging in the face of rapid global environmental change. The current di-

A

Australian Centre for Plant Functional Genomics, University of Adelaide, South Australia SA 5064, Australia. *To whom correspondence should be addressed. E-mail: [email protected]

version of substantial quantities of food into the production of biofuels puts further pressure on world food supplies (1). Breeding and agronomic improvements have, on average, achieved a linear increase in food production globally, at an average rate of 32 million metric tons per year (2) (Fig. 1). However, to meet the recent Declaration of the World Summit on Food Security (3) target of 70% more food by 2050, an average annual increase in production of 44 million metric tons per year is required (Fig. 1), representing a 38% increase over historical increases in production, to be sustained for 40 years. This scale of sustained increase in global food production is unprecedented and requires substantial changes in methods for agronomic processes and crop improvement. Achieving this increase in food production in a stable environment would be challenging, but is undoubtedly much VOL 327 SCIENCE

818

12 FEBRUARY 2010

www.sciencemag.org

Downloaded from www.sciencemag.org on August 20, 2010

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, Food Policy 30, 1 (2005). 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., Environ. Sci. Technol. 40, 1114 (2006). 28. P. Hazell, S. Wood, Philos. Trans. R. Soc. London Ser. B Biol. Sci. 363, 495 (2008). 29. K. Deininger, G. Feder, World Bank Res. Obs. 24, 233 (2009). 30. P. Collier, Foreign Aff. 87, 67 (2008). 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).

33. R. A. Gilbert, J. M. Shine Jr., J. D. Miller, R. W. Rice, C. R. Rainbolt, Field Crops Res. 95, 156 (2006). 34. IAASTD, International Assessment of Agricultural Knowledge, Science and Technology for Development: Executive Summary of the Synthesis Report, www.agassessment. org/index.cfm?Page=About_IAASTD&ItemID=2 (2008). 35. P. G. Lemaux, Annu. Rev. Plant Biol. 60, 511 (2009). 36. D. Lea, Ethical Theory Moral Pract. 11, 37 (2008). 37. Cabinent Office, Food Matters: Towards a Strategy for the 21st Century (Cabinet Office Stategy Unit, London, 2008). 38. Waste and Resources Action Programme (WRAP), The Food We Waste (WRAP, Banbury, UK, 2008). 39. T. Stuart, Uncovering the Global Food Scandal (Penguin, London, 2009). 40. FAO, www.fao.org/english/newsroom/factfile/IMG/FF9712e.pdf (1997). 41. California Integrated Waste Management Board, www.ciwmb.ca.gov/FoodWaste/FAQ.htm#Discards (2007). 42. FAO, World Agriculture Towards 2030/2050 (FAO, Rome, Italy, 2006). 43. FAO, World Agriculture Towards 2030/2050 (FAO, Rome, Italy, 2003). 44. M. D. Smith et al., Science 327, 784 (2010). 45. A. G. J. Tacon, M. Metian, Aquaculture 285, 146 (2008).

46. D. Whitmarsh, N. G. Palmieri, in Aquaculture in the Ecosystem, M. Holmer, K. Black, C. M. Duarte, N. Marba, I. Karakassis, Eds. (Springer, Berlin, Germany, 2008). 47. P. R. Hobbs, K. Sayre, R. Gupta, Philos. Trans. R. Soc. London Ser. B Biol. Sci. 363, 543 (2008). 48. W. Day, E. Audsley, A. R. Frost, Philos. Trans. R. Soc. London Ser. B Biol. Sci. 363, 527 (2008). 49. J. Gressel, Genetic Glass Ceilings (Johns Hopkins Univ. Press, Baltimore, 2008). 50. FAO, Livestock’s Long Shadow (FAO, Rome, Italy, 2006). 51. C. P. Reij, E. M. A. Smaling, Land Use Policy 25, 410 (2008). 52. UNEP, Africa: Atlas of Our Changing Environment (UNEP, Nairobi, Kenya, 2008). 53. The authors are members of the U.K. Government Office for Science’s Foresight Project on Global Food and Farming Futures. J.R.B. is also affiliated with Imperial College London. D.L. is a Board Member of Plastid AS (Norway) and owns shares in AstraZeneca Public Limited Company and Syngenta AG. We are grateful to J. Krebs and J. Ingrahm (Oxford), N. Nisbett and D. Flynn (Foresight), and colleagues in Defra and DflD for their helpful comments on earlier drafts of this manuscript. If not for his sad death in July 2009, professor Mike Gale (John Innes Institute, Norwich, UK) would also have been an author of this paper.