Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 131
A Sustainability Challenge: Food Security for All 1 ACHIEVING SUSTAINABLE FOOD SECURITY: CHALLENGES AND OPPORTUNITIES The first segment of the second workshop focused on the challenges and opportunities for achieving sustainable food security. The session began with a summary from workshop one, examining the methodologies in use to measure food and nutritional security as well as to describe key natural resources essential for assuring the sustainability of global agricultural production. Subsequent speakers talked about the need for new agricultural paradigms; trends in agricultural productivity; and key natural resource constraints, including water, land and forests, biodiversity, and soils. There was also a session examining the likely impact of climate change on future food production and related risks and vulnerabilities. Each session was followed by a brief question and answer period. CURRENT AND EXPECTED FUTURE FOOD AND NUTRITION SECURITY1 Hartwig de Haen, University of Göttingen Summary Points from Workshop One The first National Academies workshop (“Measuring Food Insecurity and Assessing the Sustainability of Global Food Systems”) discussed the various types of methodology currently in use to measure indicators of food and nutrition security. Most participants noted that the current methods do not provide fully satisfactory indicators. They often differ considerably with regard to magnitude, trends and geographical distribution of hunger in the world. de Haen noted that specific proposals were suggested for improvements of all three key methods, the Undernourishment indicator based on Food Balance Sheets (FBS), household consumption surveys and anthropometry. ____________ 1 The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_062564, presentation by Hartwig de Haen (May 2, 2011).
OCR for page 132
A Sustainability Challenge: Food Security for All Enough Is Known to Call for Urgent Action against Hunger Although we may not know the numbers of food insecure and malnourished with a high degree of accuracy, it appears safe to characterize the current state of food and nutrition insecurity as follows: Many developing countries are currently experiencing a nutrition transition. Lifestyles are becoming more urban and sedentary, with foods and drinks being more energy-dense and diets containing more processed foods, sugars, fats and animal products (Pinstrup-Andersen, 2010). The result is a triple burden of malnutrition: one part of the population is still undernourished; many also suffer from deficits of specific nutrients, in particular micronutrients; and others are overweight. Close to a billion people are chronically undernourished. While subject to possible estimation errors, the FAO (Food and Agriculture Organization of the United Nations) indicator of 850 million undernourished persons in 2005/2007 seems to be a realistic order of magnitude. First, the estimate is still lower than the number of absolutely poor (people living on less than $1.25 per day), which the World Bank estimated at 1.4 billion in 2005 (Ravallion, 2011). Secondly, FAO’s estimates are compiled using rather low rates of intra-national inequality of food availability. Many household consumption surveys show significantly higher coefficients of variation. More than 2 billion people are suffering from various forms of micronutrient deficiency. This estimate is again likely to be conservative as many people are deficient in more than one nutrient. Almost 30 percent of children under five in developing countries are underweight. Underweight is a summary indicator combining acute and persistent causes of child malnutrition. The prevalence is high but has declined during the last decade, in particular in Asia and the Pacific (UNICEF). Malnutrition is directly or indirectly associated with almost half of the 9 million child deaths per year worldwide, with the highest rates in Sub-Saharan Africa. According to WHO, 1.5 billion adults are overweight. Nearly 43 million children under five were overweight in 2010 (WHO, 2011). 65 percent of the world’s population live in countries where overweight and obesity kills more people than underweight (Uauy, 2011). These numbers underscore the fact that action is needed to fight undernourishment as well as overnourishment. Unless decisive action is taken, the number of hungry may continue to increase with rising food prices and market volatility. Agricultural supply growth is not enough to bring hunger down (FAO, 2009). What matters is that the modalities of supply growth benefit the poor (“agriculture for development”) (World Bank, 2007).
OCR for page 133
A Sustainability Challenge: Food Security for All Addressing Future Problems of Food and Nutrition Security—A Double Goal de Haen stated that there is now broad agreement among experts that to achieve the nutrition related Millennium Development Goals (MDGs) and ultimately food and nutrition security for all requires pursuing a double goal: (1) Alleviate hunger and malnutrition on a sustainable basis and (2) Create conditions for meeting the increasing demand of a growing world population. Alleviating Hunger and Malnutrition Addressing this first goal requires a strategy with three entry points: (1) Giving the poor better access to income earning opportunities. The experience of successful countries shows that public investment in rural areas, in particular investments benefitting smallholder agriculture, generates greater reduction of poverty than does investment in non-agriculture sectors. The majority of the poor still lives in rural areas. With further urbanization, more action against hunger will be needed in cities as well. (2) Social safety nets. There is now a wide array of practical experiences with social safety nets,2 which provide the neediest persons immediate access to vital social services, including food assistance, health and sanitation, education and training. In the absence of social protection, each reoccurrence of a crisis will force the poorest into unsustainable and often detrimental coping strategies. (3) Targeted nutrition improvement measures. These may range from fortification of certain foods in some countries to training for life course approaches to address obesity risks in others. Meeting the Growing Demand de Haen explained that the second strategic goal requires ensuring future production growth to meet the demand of a growing and increasingly prosperous world population.3 Whether or not the world-wide food system will succeed in meeting that growing demand on a sustainable basis will depend on the effective interplay of a number of driving factors. The most important ones are listed below. Population growth: According to the medium variant of the 2008 UN population projection, the world population is expected to reach 9.3 billion by the year 2050. More than two thirds of that population will be urban, compared with 50 percent today. Nearly the entire increase will occur in today’s developing countries, with the largest increase in Asia. ____________ 2 See, for example, B. Guha-Khasnobis, S. S. Acharya, and B. Davis (Eds.) 2007. Food Insecurity, Vulnerability and Human Rights Failure. UNU-Wider. 3 Production growth is also needed to enable today’s almost one billion undernourished to increase consumption to the minimum requirements. Depending on the food gap to be filled, this would require between 30 and 50 million tons of grain equivalents, hence a small fraction of today’s total supplies.
OCR for page 134
A Sustainability Challenge: Food Security for All Income growth: According to the World Bank, “In most developing countries, GDP has regained levels that would have prevailed had there been no boom-bust cycle” (World Bank, 2011). With this prospect, the developing countries, especially in Asia, but also in Central and Eastern Europe and in many countries of Sub-Saharan Africa, are expected to resume their strong economic growth. Demand growth: The projected population and income growth are likely to translate into strong growth of per caput demand for agricultural products. However, some of the more populous countries like China and Brazil are moving towards saturation levels. Thus the gradual slowdown of overall demand growth is likely to continue. According to FAO’s projection to 2050, published in 2009, global demand for agricultural products is expected to grow by about 70 percent compared to 2005/2007.4 Resource constraints, climate change and sustainable intensification: The task ahead is daunting considering the multiple resource constraints. Until 2050, the area of agricultural crop land per person is likely to decline further; already today, 1.4 billion people are living in areas with declining ground water levels (World Bank, 2007), two thirds of the agricultural ecosystems are more or less degraded, the genetic resource base for future plant breeding is faced by various risks, and the burden of adjustment to climate change falls disproportionately on the rural areas of the southern hemisphere. In view of these resource constraints, about 80 percent of the projected supply growth will have to originate from sustainable intensification (i.e., productivity growth that minimizes negative environmental implications, contributes positive environmental services and is generally integrated into an ecosystems approach) (Bruinsma, 2009). Reducing waste and losses: In the light of the constraints to natural resources, efforts to reduce waste and losses should be seriously considered. According to various sources, waste and spoilage causing useless input of land, water, feed and energy could be in the order of 30 to 40 percent of agricultural production world-wide.5 Trade and market structure: Even with high growth of their own production, the developing countries as a group will face a significant widening of their net trade deficit for basic food stuffs—enhancing export opportunities for agriculture of developed countries. This perspective will make it even more important that trade rules and market structures enable poorer countries to generate export surpluses in other goods and services, including tropical products. Perspectives for Reduction of Hunger and Malnutrition Both main organizations with long term projections of world agriculture, FAO and IFPRI, include food security indicators in their projections. These are generated on the basis of certain assumptions regarding future changes in the intra-country inequality of access to food. While FAO’s projections use the same indicator (undernourishment) that is used to monitor past ____________ 4 Provisional estimate made in mid-2009 (Bruinsma, 2009) indicated 70 percent. This was based on projections to 2050 made in 2003-2005 (FAO, 2006). Work in FAO underway for updating the projections. 5 According to sources cited by UNEP, even “57 percent of the potential edible crop harvest was lost during different stages of conversion from crop to food or as food waste” (UNEP Brief, undated, “Agriculture, a Catalyst for Shifting to a Green Economy”).
OCR for page 135
A Sustainability Challenge: Food Security for All food security, IFPRI uses child underweight as an indicator of malnutrition. According to FAO’s latest projection (Alexandratos, 2009), using one trajectory considered most realistic, undernourishment is expected to decline. The decline is rather slow, so that the target of halving the number of undernourished between 1990/1992 and 2015, set by the World Food Summit in 1996, will be achieved only just before 2050. IFPRI’s projections also indicate a decline in malnutrition. It shows in various scenarios the importance of economic development in reducing child malnutrition. In an optimistic scenario, the number of malnourished children in developing countries falls by almost 46 percent between 2010 and 2050. Child malnutrition would fall even under a pessimistic scenario, though by only 2 percent. These perspectives imply a reversal of the recent trend of rising chronic hunger. de Haen explained that none of the studies considers explicitly how alternative policies, including both production and consumption related policies, would be effective in changing that trend. Conclusion—Main Challenges Effective reduction of food and nutrition insecurity requires a deliberate double effort: One is action to improve the access to income earning opportunities for today’s hungry and to ensure social protection, including immediate access to food for the neediest. The other is investment in sustainable, longer-term agricultural growth and development. Action and behavioral change will be needed at all levels—individual, corporate, and public. Governments in all countries also have a key responsibility in establishing the enabling conditions for effective and sustainable improvements, within a framework of political stability and good governance. They must have the political will to change priorities, mobilize public investment and reform institutions in favor of sustainable food and nutrition security. de Haen stated that a guiding principle must be combining measures to reduce hunger with investment in sustainable growth of food supplies. In many countries, this will require a focus on rural smallholders, representing the majority of the poor, but it must increasingly also address urban food security problems. AGRICULTURAL PRODUCTIVITY AND NATURAL RESOURCE ENDOWMENTS6 Philip Pardey, University of Minnesota Philip Pardey opened this session of the workshop by raising a number of critical questions—what are past and prospective rates of agricultural productivity growth, how do these rates relate to changes in demand, how have natural resource endowments changed over time, and what are the links between the flows of natural input services to and from agriculture? He suggested that there were three key indicators associated with agricultural productivity—what is produced, where it is produced, and how it is produced. Moreover, the biological processes that ____________ 6 The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_062564, presentation by Philip Pardey (May 2, 2011).
OCR for page 136
A Sustainability Challenge: Food Security for All underpin production agriculture underscore the need for a spatially sensitive view of production, given spatial variation in the natural inputs that are distinctively used in agriculture. Pardey stressed the importance of understanding past and likely future trends in agricultural productivity relative to corresponding changes in the demand for agricultural outputs, since differential rates of supply (productivity) and demand growth will cause agricultural commodity prices to change over time, with direct hunger and poverty consequences. He also explained that if U.S. agricultural productivity had not increased substantially between 1900 and 2008, an area equivalent to the entire area east of the Mississippi would have had to be cultivated to reach the level of cereal production attained in 2008, with far reaching natural resource consequences. Pardey noted two sets of important drivers of productivity change that are typically ignored by traditional productivity measurements: (1) natural inputs, such as weather, terrain, and soil types, and (2) pests and diseases. All of these natural inputs vary across time and space, making it difficult to identify the degree to which these factors account for measured variation in agricultural productivity vis-à-vis the effects of other factors, including differences in the scale (and structure) of production and unmeasured changes in the quality of conventional inputs (such as land, labor and capital). He also emphasized the important productivity consequences of technological changes arising from investments in public and private agricultural research and development (R&D). However, the agricultural productivity consequences of R&D and changes in the natural resource base play out over many decades, adding to the difficulty of attributing measured changes in productivity to either of these (or other) factors. For example, almost 60 years passed from the conception of hybrid corn to its commercial release. There are alternative, conventional measures of productivity, be they partial-, total- or multi-factor measures.7 Consider crop yields, for example, as one seemingly straightforward and illustrative partial-factor productivity measure. Figure II 1-1 illustrates the difficulties in measuring and understanding differences among countries in average crop yields. The figure shows pixilated crop yields (on a five arc-minute grid) worldwide for four crops, with production areas stratified into yield deciles (1 being areas with the lowest 10 percent of yields worldwide, and 10 representing areas with the highest yields). The inset table indicates that in 2000 the United States accounted for 32 percent of the world’s corn pixels that fall in the three highest yielding deciles, while Africa accounts for only 2.5 percent of such high-yielding pixels. ____________ 7 As Alston, Babcock and Pardey (2010, p. 452) observed, “Individual grain yield is an example of a partial factor productivity (PFP) measure. It is ‘‘partial’ in the sense that it only accounts for changes in the amount of land used in production. It does not account for changes in the quantities of other inputs—such as labor, capital, fertilizer, rainfall, or irrigation—that also affect production. Thus yield and other partial measures can be seen as partial with respect to their treatment of outputs as well as inputs. At the opposite end of the spectrum are measures of total factor productivity (TFP), the aggregate quantum of all outputs divided by the aggregate quantum of all of the inputs used to produce those outputs. TFP is a theoretical concept. All real-world measures omit at least some of the relevant outputs and some of the relevant inputs, and therefore it is more accurate to refer to the real-world measures as multifactor productivity (MFP) measures.”
OCR for page 137
A Sustainability Challenge: Food Security for All FIGURE II 1-1 Spatial Distribution of Crop Yields, 2000 (SPAM ver 3.0) SOURCE: Presentation by Philip Pardey, University of Minnesota, May 2, 2011. Each of these pixels is associated with a set of natural resource attributes (in terms of rainfall, soil nutrients and organic matter, temperature, sunlight, and so on), and to the extent that these natural attributes affect crop yields, differences in the spatial location of production within the United States versus Sub-Saharan Africa will also affect crop yields. But these natural attributes are rarely measured, thereby confounding our interpretation of the sources of productivity (yield) differences among countries. Thus, in this instance, to what extent do differences in (unmeasured) natural inputs between the United States and Sub-Saharan Africa account for differences in average corn yields versus differences, say, in the amount, nature and effectiveness of R&D in these two areas of the world? Moreover, to the extent that the location of production within a country changes over time (and thereby the implicit mix of natural inputs), the problem of disentangling the productivity consequences of natural inputs from other factors is made doubly difficult. Meaningful advances in our state of understanding about the nexus between natural resources and agricultural productivity are likely to hinge on at least two fundamental factors. First is the need for a spatially explicit view of agricultural production processes given the spatial variation in the biological processes that define production agriculture. Second is the need to take a long-run perspective, likely decades rather than years, given the timeframes it typically takes for natural input cum agricultural productivity processes to play out.
OCR for page 138
A Sustainability Challenge: Food Security for All ARE NEW PARADIGMS NEEDED FOR SUSTAINABLE FOOD SECURITY IN THE FACE OF UNCERTAINTIES AND RISKS?8 Marco Ferroni, Syngenta Foundation for Sustainable Agriculture The world’s food security is under threat because of the “double squeeze” on productive capacity, which stems from rapid demand growth and a deteriorating natural resource base, which is increasingly unpredictable due to climate change. The average annual rate of growth of cereal yields has declined from more than 3 percent in the 1980s to close to 1 percent in recent years, a level just below the rate of population growth. There is little room in this situation for the food system as a whole to absorb income growth-induced additions to demand or accommodate production shortfalls due to adverse weather. Prices had to (and did) rise, and they became more volatile as markets adjusted to such factors as changes in grain stocks relative to use, export restrictions, currency movements, fluctuations in the price of oil, financial speculation and subsidies for biofuels that added to the demand for commodities that competed with food for land and water. Globally speaking, agriculture is under stress. For this reason, many analysts and observers have remarked that, as we look to the future, “business as usual” in agriculture will not suffice. The world needs to grow more food, in addition to taking other measures such as the reduction of post-harvest losses and waste in the supply chain. This will require new models and approaches. Going forward, the production-based approach of the Green Revolution that sought cheap and abundant supplies of food is no longer comprehensive enough. The needed increases in food production must be brought about sustainably, using natural resources wisely to be able to “indefinitely meet the requirements for food, feed and fiber at socially acceptable economic and environmental cost” (Crosson, 1992). Increases in food production can come from agricultural intensification, the expansion of the agricultural frontier, or a combination of the two. Although there are untapped reserves of land and water, to be sure (mostly in Sub-Saharan Africa, Latin America, Eastern Europe and Central Asia), most of the required growth in global production is going to have to come from intensification, because land and water are finite assets already overused in many places. Sustainable intensification can be defined as “producing more output from the same area of land while reducing the negative environmental impacts and at the same time increasing contributions to natural capital and the flow of environmental services” (Pretty, 2011). These are requirements with many implications, but the place to start is yield. Yield gaps are huge in many settings as shown in Figure II 1-2.9 They need to be reduced and closed as part of intensification. Reducing yield gaps will also raise the efficiency of water use.10 It has been shown that in grains and other field crops, the correlation between water use efficiency and yield per unit of land is high. ____________ 8 The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_062564, presentation by Marco Ferroni (May 2, 2011). 9 Yield gap can be defined as the difference between realized productivity and the best that can be achieved with current genetic material and available technologies and management. 10 Liters of water used to produce a unit of grain.
OCR for page 139
A Sustainability Challenge: Food Security for All The literature on yield gaps is quite large, and reviewing it is beyond the scope of this presentation. One study that looked at yield gaps for major crops, and world regions recently defined five production constraints and invited a group of experts to assign weights to them to reflect their relative importance (Hengsdijk and Langeveld, 2009). The experts queried were experienced crop specialists from national and international research institutions. Figure II 1-2 shows the study’s estimates of the contribution of the five production constraints to the theoretical maximum yield gap for corn in different parts of the world. It is instructive to see for South Asia, for example, that the estimated yield gap is close to 8 t/ha and is thus very large, because of limited water availability, limited nutrient availability, inadequate protection of the crop from pests and diseases, insufficient or inadequate use of labor or mechanization, and knowledge deficits that result in poor crop management. The authors acknowledge the difficulty of measuring and comparing yield potentials and actual yield across a range of conditions. Their results are indicative. But the relative contribution of the factors accounted for in Figure II 1-2 is telling, and, for example, the point about knowledge as a constraint on yield makes it quite clear that there is an unmet need for agricultural extension. FIGURE II 1-2 Maize yield gap by region and contribution of five production constraints SOURCE: Hengsdijk and Langeveld, 2009 The task of reducing and closing yield gaps calls for appropriate farm systems management, inputs and technology, services and access to markets. Infrastructure, finance, weather data and risk insurance are among the critical components on the input side, as are functioning markets and distribution systems for seed, fertilizer, tools and appropriate mechanization. Science-based advances and technology are central, including soil testing, improved seed and varieties, seed treatment, new and improved fertilizer technology, micro-irrigation, precision farming and agricultural extension. Mobile phone based applications in
OCR for page 140
A Sustainability Challenge: Food Security for All agriculture have begun to revolutionize the linkages and transactions between farmers and service providers of many kinds. They are the “up and coming” tool for scaling up extension and linking farmers to input and output markets. Markets for food and agricultural commodities offer hitherto unseen opportunities for farmers, including small farmers in developing countries and emerging markets. Small farmers no longer want to be seen as subsistence farmers they are, or aspire to become, commercial producers. They are looking for ways to secure access to technology, services, infrastructure such as roads, and markets. Farmers’ organizations are serving an increasingly important role in providing access to these. Although the farmers’ share of the consumers’ dollar at retail tends to be small, organized growers who are working the land with the right kinds of inputs and support and selling into established markets can improve their livelihoods and invest in their future.11 There cannot be sustainability in agriculture without this. However, in many parts of the world, there remain serious barriers to expanding smallholder production: unhelpful governance and institutions, lack of public goods, inadequate services such as credit and extension services for farmers, and land fragmentation. New paradigms are needed in global agriculture and are emerging: productivity and sustainability are inseparable, markets and consumers are driving change, and agriculture and farming remain important even as economies evolve. Approaches to the food security challenge that focus solely on production are inadequate. Intensification is called for as never before, but it must come about sustainably, heeding on-site and off-site environmental conservation and rehabilitation opportunities and needs; and adapting to, and working to mitigate, climate change. Intensification must take cues from the market and respond to the quantitative and qualitative changes in tastes and demand that are visible wherever one looks, complying with the product and safety standards that modern markets demand. Food safety, standards, and the power of consumers are part of the new reality to contend with—a reality that (together with the liberalization of markets) is shifting agriculture in developing countries and emerging markets from the grains- and staple-based subsistence focus of the past towards high-value, information-intensive, commercial farming. Many smallholders are participating in this trend successfully today; many more should be and—with the right kinds of services and support—can be brought into the process to help fill supply gaps, raise incomes and promote agricultural growth. Agricultural growth and the adoption of technical progress by farmers are needed even as the sector’s share in countries’ GDP falls. The economic transformation whereby agricultural GDP declines rapidly relative to the total, and agricultural employment declines slowly, is in full swing. Sustainable progress and productivity growth in agriculture are needed for at least six good reasons in this context, all of which relate to and reinforce food security: food availability, conservation of natural resources, diversification of the rural economic space and rural non-farm employment, overall economic growth, poverty reduction, and income convergence between the agricultural and non-agricultural sectors of the economy. To get there, we need enlightened investment in agriculture. Farming first is a good maxim to go by, accepting sustainability and market-driven, science and technology-based modernization as two sides of the same coin. ____________ 11 Reardon and Gulati offer an analysis of how the transformation of supply chains and marketing creates opportunities and challenges when it comes to linking farmers to markets. The organization of farmers becomes essential to lower transactions costs from buyers’ perspective and to raise farmers’ bargaining power. See Reardon, T. and A. Gulati. 2008. The Rise of Supermarkets and their Development Implications. IFPRI Discussion Paper 00752.
OCR for page 141
A Sustainability Challenge: Food Security for All GENERAL DISCUSSION Participants raised a number of questions regarding productivity increases—what this might mean in terms of prices and ways to stimulate increased productivity. One participant asked whether farmers were likely to increase production to such an extent that food prices would fall. Marco Ferroni indicated that this could happen if productivity rose enough, because farmers are price responsive. He noted, however, that abundant global food supplies and falling prices are unlikely in the foreseeable future because increases in the demand for food are expected to be very large in many developing countries as their incomes grow while production prospects are challenged by natural resource degradation and the threat of climate change. One speaker emphasized the importance of spillover effects, noting that managing such effects is critical to promoting the use of new agricultural technologies. In fact, he suggested that part of the success of the green revolution was due to the friendship between Norman Borlaug and the Indian minister of agriculture. Other speakers emphasized the importance of continuing support for R&D and mentioned that by reducing U.S. agricultural subsidies by 10 percent and shifting these funds to R&D, U.S. public R&D funding could be doubled. It was also noted that much of the private R&D funding is not directed at food crops but rather at ornamentals— flowers, houseplants and grasses. Ferroni stressed the importance of political commitment to agriculture, private and public investment in agricultural R&D, and technical support to farmers (for example in the form of agricultural extension) to help raise yields and productivity sustainably. He cited the example of Gujarat, a relatively natural resource poor state, where agricultural production increased up to 10 percent a year because of dedicated government support. WATER FOR A FOOD-SECURE WORLD12 David Molden, IWMI David Molden began the session by describing the link between water and food. Estimates place the need for additional food production at about 70 to 100 percent more than we produce now. More food requires more water. Agriculture now takes 70 percent of global water withdrawals. If we continue producing food the way we do now, up to twice as much would go into food production in the form of evapo-transpiration through 2050. Given that we have water scarcity now; that we have reached or surpassed limits already with groundwater decline, shrinking rivers and threatened fisheries; and that climate change brings more risk and uncertainty; we must change the way we think and act about water. ____________ 12 The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_062564, presentation by David Molden (May 2, 2011).
OCR for page 154
A Sustainability Challenge: Food Security for All increase demand for high value foods such as meat, fish, fruits, and vegetables. And climate change will be a “threat multiplier,” affecting cropping systems worldwide. Nelson’s presentation focused on three major themes: the current state of knowledge about climate change; the impact of climate change on crop yields, supply, demand and trade; and the assessment of the challenge of long term food security with and without climate change. Basing his discussion on direct climate change effects on a suite of four possible climate futures, Nelson stated that average temperatures would likely increase substantially—especially after 2050—and that major changes in precipitation patterns are possible. He also said that there will be increased variability in temperature and precipitation patterns. He pointed out that there are big differences among model outcomes in terms of the location and magnitude of these changes. Nelson noted that the combined effects of higher temperatures and more varied precipitation were likely to have widespread negative consequences for agricultural yields. Average increases in temperature alone would have some impact on productivity, but if temperatures spike during critical growth periods, crop yields would be much more seriously affected than average temperature increases would suggest. Important outputs of the scenarios are estimates of future changes in precipitation. Interestingly, the two models, one from the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO) and the other from the University of Tokyo’s Center for Climate System Research (MIROC), yield very different outcomes. The CSIRO model has smaller and more evenly distributed increases in precipitation, whereas the MIROC model has larger average increases with decreased rainfall predicted in important world agricultural regions. See slides below (Figures II 1-6; 1-7): FIGURE II 1-6 Change in average annual precipitation, 2000-2050 CSIRO GCM, A1B (mm) SOURCE: Presentation by Jerry Nelson, IFPRI, May 2, 2011.
OCR for page 155
A Sustainability Challenge: Food Security for All FIGURE II 1-7 Change in average annual precipitation, 2000-2050 MIROC GCM, A1B (mm) SOURCE: Presentation by Jerry Nelson, IFPRI, May 2, 2011. See the slide below (Figure II 1-8), which displays changes in maize yields with the MIROC model outputs. FIGURE II 1-8 Yield Effects, Irrigated Rice, MIROC A1B (percent change between 2000 and 2050 climate) SOURCE: Presentation by Jerry Nelson, IFPRI, May 2, 2011.
OCR for page 156
A Sustainability Challenge: Food Security for All Nelson described a set of plausible scenarios developed by IFPRI based on three overall income/population scenarios and five climate scenarios for a total of 15 plausible futures. World prices are an important indicator of the combined effects of income, population and climate. The slide below shows both the mean price increases with and without climate change as well as the range of increases that arise with different climate scenarios, holding income and population growth patterns constant. FIGURE 1-9 Climate Change Scenario Effects Differ (The vertical axis represents price increase [percent], 2010-2050, baseline economy and demography) SOURCE: Presentation by Jerry Nelson, IFPRI, May 2, 2011. In order to increase food security and resilience to climate change, Nelson suggested that three specific objectives must be met: broad based economic growth, investments targeted to increase agricultural productivity, and strengthened international trade agreements. He emphasized the need to raise poor people’s incomes to achieve food security and increase climate change resilience. The scenarios described above suggest that the benefits of broad-based economic growth are greatest in middle income countries where there could be as much as a 50 percent decline in the number of malnourished children under an optimistic scenario. A pessimistic scenario results in a decline in the number of malnourished children of only about 10 percent on average, with a 20 percent increase in low-income developing countries. Nelson said that although it is still possible to expand the amount of land under cultivation, most productivity increases are likely to result from increasing investment in existing agricultural lands. Such investments should focus on expanding irrigation and improved irrigation efficiency, biological research, and the expansion of rural roads.
OCR for page 157
A Sustainability Challenge: Food Security for All He concluded that future climate variability will likely stimulate expanded trade flows from countries experiencing expanded agricultural production levels to those with contracting levels of production. Trade should help reduce some of the human suffering likely to occur from food shortages. RISKS AND VULNERABILITIES FROM CLIMATE CHANGE19 David Lobell, Stanford University This presentation focused on the risks that climate change poses to global food production. David Lobell noted that the emphasis on global scale should not detract from the fact that different regions could be affected differently, or that different uncertainties may be more relevant at some scales than at others. Below is a brief summary of the main points of the presentation. Climate change represents a significant challenge to maintaining productivity growth rates in global agriculture. Early work on this topic suggested that the benefits of higher CO2 should more than compensate for any climate-related losses in global productivity until 2-3°C of global mean temperature increase. These assessments predicted that climate change would hurt developing countries before that time, but that gains in higher latitudes would buffer the global impacts. More recent work has painted a slightly more challenging picture, for two main reasons. First is that the harmful effects of warming appear stronger than initially thought, in particular for the effects of extreme heat on crop production. Early model results often suggested that adopting longer maturing varieties or earlier plantings would be an effective adaptation, but the fact that extreme heat is damaging and not included in most models challenges this view. In particular, there is little evidence for greater tolerance of extreme heat for corn grown in hot vs. cool locations. Second is that the beneficial effects of CO2 as measured in chamber or greenhouse experiments seem to be higher than what has been observed in field experiments. This appears to reflect the fact that moisture conditions in enclosed experiments were generally lower, which led to strong effects on water use efficiency, which were misinterpreted as photosynthesis effects. Although some modelers have claimed that the values used in past model assessments agree with field experiment results, it appears that the modeled responses that include water use efficiency effects are indeed much stronger than observed. In addition to CO2 and temperature, changes in drought frequency are likely throughout much of the tropics and subtropics, and increases in pest and disease pressures will likely be more severe in several regions. Moreover, floods are increasingly common and will likely ____________ 19 The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_062564, presentation by David Lobell (May 2011).
OCR for page 158
A Sustainability Challenge: Food Security for All continue to be so, and ozone damage (which is in part facilitated by higher temperatures) is substantial. The effects of all of these changes are still poorly quantified at the global scale, but in sum they are likely to represent a significant challenge to maintaining productivity growth. Adapting to climate change is likely to be one of the handful of key factors going forward (along with increasing input use and efficiency, maintaining rust and disease resistance…). Given the above considerations, our ability to adapt to climate change is one of the major uncertainties in future food supply. It is equally or more important to increase input use in Africa, to increase the efficiency of input use globally, and to improve resistance to major rusts and diseases. All of these, including climate adaptation, are of course linked to an underlying challenge—the declining investments in agriculture and the long time lags in the system (as emphasized by Pardey’s talk20). The clearest risk (estimation) is from extreme heat, the main opportunity is higher CO2. Despite much attention and concern about changes in precipitation, and the significant role that rainfall changes might play at regional scales, the global challenges result mainly from increased temperatures. Note that this does not diminish the importance of drought tolerance, because trends in drought are often driven by greater evaporation rates associated with warming. Targeting crop development to higher CO2 environments represents an untapped strategy that could more fully exploit the benefits of higher CO2. The clearest problem crops are wheat and maize (assuming that rice continues to have water, and that roots/tubers benefit a lot from CO2). Although maize is typically thought of as a heat tolerant crop, it is already grown in some of the harshest environments where further warming will be detrimental. Wheat is a cool season crop, which is hurt in most places from warming. A possible exception is where warming allows one to switch from spring to winter wheat varieties. Rice appears less sensitive, although it is still affected. In particular, rice is damaged from high day temperatures during flowering, which can cause spikelet sterility. Tuber crops appear in experiments to benefit the most from higher CO2, although their sensitivity to temperature and moisture changes are less well known. ____________ 20 See Agricultural Productivity and Natural Resource Endowments by Philip Pardey.
OCR for page 159
A Sustainability Challenge: Food Security for All The public sector can play an important role in adapting, particularly in regard to genetic conservation, heat stress and CO2 responsiveness. The private sector will obviously play an important role in innovation, in particular for developed countries and for crop traits that are already considered important for yields (such as drought, which is increasingly the target of seed companies). But for crops without a large private sector, and for traits without much interest in current climate, there is a need for sustained public investment. This is especially true given the lags in return on research investments, which means that crops being developed today will likely reach farmers in a significantly warmer world, and one with higher CO2. There are very likely already sizable losses being incurred from climate change, which at a time of biofuel mandates and high prices, translates to ~$50 billion per year. The results of a recent analysis were presented, which examined effects of changes to date. Although climate change is often thought of as a risk to future production, many regions have already experienced significant shifts. The analysis revealed a few important points: (i) The warming rates are such that net negative impacts at the global scale are apparent. (ii) Even with positive effects of higher CO2, the sum of climate and CO2 trends has been negative. This is not exactly analogous to the studies mentioned in the first point above, because we examined actual climate trends, not the component of climate trends forced by higher greenhouse gas concentrations. (iii) There are important differences between crops, with maize and wheat showing losses (see the fourth point above), but rice and soybean less so; (iv) There are important regional differences, with North America less affected than other regions. Whether or not these same regional differences persist will depend on better understanding the causes of recent regional climate trends. Overall, the impact of warming could be affecting productivity enough to alter conclusions from analysis of trends in multi-factor productivity discussed by Pardey and others, and also represents a likely minor but non-trivial cause of the increase in food prices over the past decade. The results suggest that the added stress from warming since 1980 leads to roughly $200 billion in lost productivity, representing a big payoff for effective adaptation. Gains from higher CO2 likely offset about three-fourths of this loss. Although $50 billion per year can be viewed as a small fraction of overall agricultural value, the impacts are likely to grow with time, as illustrated in the previous talk. Lobell stated that the fact that we already see sizable effects means that adaptation efforts are useful not only for the future, but also for today. GENERAL DISCUSSION The discussion following the climate change presentations focused largely on the models used in the analysis—the elements included in the models and the extent to which potential impacts were not assessed. One speaker noted that an important effect of climate change is dramatic changes in the length and timing of the growing season. He noted that these changes
OCR for page 160
A Sustainability Challenge: Food Security for All may require farmers to shift from traditional crops to other crops that are easily adapted to changes in the growing season as well as changes in the length of the rainy season. Other speakers noted that the IFPRI model assumes that the supply of land is very inelastic—that large price changes in crop prices will not cause much change in net agricultural land. Other models discussed by Gerry Nelson assume the land supply is more elastic, and this is a major reason for differences in results from various models of long run changes in global agricultural output growth. Several questions were raised about the potential impacts on agriculture of increased CO2 levels. David Lobell said that these increases could decrease the amount of water consumed in forested areas, making more runoff available for agricultural crops. But he noted that higher projected temperatures and evaporation rates could reduce this effect. In addition, he noted that increased CO2 helps most when crops have sufficient nitrogen. But in many cases, African soils have limited nitrogen, and the costs of nitrogen based fertilizers are high, so the increased CO2 is not likely to spur productivity increases in Africa. Another issue not generally included in the climate models is the potential increase in ozone levels, which tend to decrease agricultural yields. REFERENCES de Haen Alexandratos, N. 2009. World Food and Agriculture to 2030/50: Highlights and Views from Mid-2009. Expert Meeting on How to feed the World in 2050. Rome, Italy: FAO (Food and Agriculture Organization of the United Nations). Bruinsma, J. 2009. The Resource Outlook to 2050: By How Much do Land, Water Use and Crop Yields need to Increase by 2050? Expert Meeting on How to Feed the World in 2050. Rome, Italy: FAO. FAO. 2009. Feeding the World, Eradicating Hunger, Background Document WSFS 2009/INF/2 of the World Summit on Food Security. Rome, Italy: FAO. Guha-Khasnobis, B., S. S. Acharya and B. Davis, eds. 2007. Food Insecurity, Vulnerability and Human Rights Failure. Hampshire, UK: Palgrave Macmillan. Pinstrup-Andersen, P. 2010. Understanding the Interactions between Agriculture and Health. IFPRI (International Food Policy Research Institute) 2020 Panel Discussion. Washington, DC: IFPRI. Ravallion, M. 2011. Paper presented at the National Academies first workshop, Measuring Food Insecurity and Assessing the Sustainability of Global Food Systems. February 16-17, 2011. Washington, DC. The World Bank. 2007. World Development Report 2008: Agriculture for Development. Washington, DC: The World Bank:182. The World Bank. 2011. Global Economic Prospects: Maintaining Progress Amid Turmoil. Washington, DC: The World Bank. Uauy, R. 2011. Measures of Overnutrition/Obesity. Paper presented at the National Academies first workshop, Measuring Food Insecurity and Assessing the Sustainability of Global Food Systems. February 16-17, 2011. Washington, DC. UNEP (United Nations Environment Programme). 2009. Agriculture: A Catalyst for Shifting to a Green Economy. A UNEP Brief.
OCR for page 161
A Sustainability Challenge: Food Security for All WHO (World Health Organization). 2011a. Obesity and overweight: Fact sheet N°311. Available at http://www.who.int/mediacentre/factsheets/fs311/en. Pardey Alston, J. M., B.A. Babcock and P.G. Pardey, eds. 2010. The Shifting Patterns of Agricultural Production and Productivity Worldwide. CARD-MATRIC on-line volume. Ames: Iowa State University. 2010. Available at www.matric.iastate.edu/shifting_patterns. Ferroni Crosson, R. 1992. Sustainable Agriculture. Quarterly Newsletter. Washington, DC: Resources of the Future. Hengsdijk, H. and J. W. A Langeveld. 2009. Yield trends and yield gap analysis of major crops in the world. Werkdocument 170. Wageningen, The Netherlands: Wageningen University. Pretty, J. 2011. Editorial: Sustainable intensification in Africa. Pp. 1-9 in Sustainable Intensification: Increasing Productivity in African Food and Agricultural Systems, J. Pretty, C. Toulmin and S. Williams, eds. London, UK: Earthscan. Reardon, T., and A. Gulati. 2008. The Rise of Supermarkets and their Development Implications. IFPRI Discussion Paper 00752. Molden Bossio, D., and K. Geheb. eds. 2008. Conserving land, protecting water: Comprehensive Assessment of Water Management in Agriculture Series 6. Wallingford, UK: CABI; Colombo, Sri Lanka: IWMI (International Water Management Institute); and Colombo, Sri Lanka: CGIAR Challenge Program on Water and Food:xi-xviii. Dugan, P., V. V. Sugunan, R. L. Welcomme, C. Bene, R. E. Brummett, M. C. M. Beveridge, K. Abban, U. Amerasinghe, A. Arthington, M. Blixt, S. Chimatiro, P. Katiha, J. King, J. Kolding, S. N. Khoa, and J. Turpie. 2007. Inland Fisheries and Aquaculture. Pp. 459-483 in Water for Food, Water for Life: A Comprehensive Assessment of Water Management in Agriculture, D. Molden, ed. London, UK: Earthscan and Colombo, Sri Lanka: IWMI. Giordano, M., and K.Villholth, eds. 2007. The Agricultural Groundwater Revolution: Opportunities and Threats to Development: Comprehensive Assessment of Water Management in Agriculture Series 3. Wallingford, UK: CABI:419. Molden, D., ed. 2007. Water for Food, Water for Life: A Comprehensive Assessment of Water Management in Agriculture. London: Earthscan and Colombo, Sri Lanka: IWMI:645. Rockstrom, J., N. Hatibu, T. Y. Oweis, S. Wani, J. Barron, A. Bruggeman, J. Farahani, L. Karlberg, and Z. Qiang. 2007. Managing water in rainfed agriculture. Pp. 315-352 in Water for Food, Water for Life: A Comprehensive Assessment of Water Management in Agriculture, D. Molden, ed. London, UK: Earthscan; Colombo, Sri Lanka: IWMI.
OCR for page 162
A Sustainability Challenge: Food Security for All Shah, T. 2007. The groundwater economy of South Asia: an assessment of size, significance and socio-ecological impacts. Pp. 7-36 in The Agricultural Groundwater Revolution: Opportunities and Threats to Development: Comprehensive Assessment of Water Management in Agriculture Series 3, M. Giordano and K. G. Villholth, eds. Wallingford, UK: CABI. Wani, S.P., T.K. Sreedevi, J. Rockstrom, and Y.S. Ramakrishna. 2009. Rainfed agriculture: past trends and future prospects. Pp. 1-35 in Rainfed agriculture: unlocking the potential: Comprehensive Assessment of Water Management in Agriculture Series 7, S. P. Wani, J. Rockstrom, and T. Oweis, eds. Wallingford, UK: CABI; Patancheru, Andhra Pradesh, India: International Crops Research Institute for the Semi-Arid Tropics; Colombo, Sri Lanka: IWMI. Vlek FAO. 2010. Global Forest Resources Assessment 2010. Rome, Italy: FAO. Kanninen, M., D. Murdiyarso, F. Seymour, A. Angelsen, S. Wunder, and L. German. 2007. Do Trees Grow on Money? The Implications of Deforestation Research for Policies to Promote REDD. Bogor, Indonesia: Center for International Forestry Research. Millennium Ecosystem Assessment. 2005. Ecosystems and Human Well-being: Synthesis. Washington, D.C: Island Press. Vlek, P. L. G., Q. B. Le, and L. Tamene. 2008. Land Decline in Land-Rich Africa: A Creeping Disaster in the Making. Rome, Italy: CGIAR Science Council Secretariat. Vlek, P. L. G., Q. B. Le, and L. Tamene. 2010. Assessment of land degradation, its possible causes and threat to food security in sub-Saharan Africa. Pp. 57-86 in Advances in Soil Sciences—Food Security and Soil Quality, R. Lal and B.A. Stewart, eds. Boca Raton: CRC Press. Benton Battisti, D. S., and R. L. Naylor. 2009 Historical warnings of future food insecurity with unprecedented seasonal heat. Science 323:240-244. Bruinsma, J. 2009. The resource outlook to 2050: by how much do land, water and crop yields need to increase by 2050? Expert Meeting on How to Feed the World in 2050. Rome, Italy: FAO. Clay, J. 2010. Agriculture from 2000 to 2050-The Business as Usual Scenario. Washington, DC: Global Harvest Initiative. Costanza, R., R. d’Arge, and M. van den Belt. 1997. The value of the world’s ecosystem services and natural capital. Nature 387(6630):253-260. Dyer, J. C., L. C. Stringer, and A. J. Dougill (submitted). Jatropha curcas: Sowing local seeds of success in Malawi. Submitted to Journal of Arid Environments. Elbert, W., B. Weber, B. Büdel, M. O. Andreae, and U. Pöschl. 2009. Microbiotic crusts on soil, rock and plants: neglected major players in the global cycles of carbon and nitrogen. Biogeosciences 6:6983-7015 Fischer, G., H. van Velthuizen, M. Shah, and F. Nachtergaele. 2002. Global Agro-ecological Assessment for Agriculture in the 21st Century: Methodology and Results. Laxenburg, Austria: IIASA. Gabriel, D., S. J. Carver, H. Durham, W. E. Kunin, R. C. Palmer, S. M. Sait, S. Stagl, T. G. Benton. 2009. The spatial aggregation of organic farming in England and its underlying environmental correlates. Journal of Applied Ecology 46(2):323-333.
OCR for page 163
A Sustainability Challenge: Food Security for All Gabriel, D., S. M. Sait, J. A. Hodgson, U. Schmutz, W. E. Kunin, and T. G. Benton. 2010. Scale matters: the impact of organic farming on biodiversity at different spatial scales. Ecology Letters 13(7):858-869. Gallai, N., J. M. Salles, J. Settele, and B. E. Vaissiere. 2009. Economic valuation of the vulnerability of world agriculture confronted with pollinator decline. Ecological Economics 68(3):810-821. Godfray, H. C. J., J. R. Beddington, I. R. Crute, L. Haddad, D. Lawrence, J. F. Muir, J. Pretty, S. Robinson, S. M. Thomas, and C. Toulmin. 2010. Food Security: The Challenge of Feeding 9 Billion People. Science 327(5967):812-818. Green, R. E., S. J. Cornell, J. P. W. Scharlemann, and A. Balmford. 2005. Farming and the fate of wild nature. Science 307(5709):550-555. Hodgson, J. A., W. E. Kunin, C. D. Thomas, T. G. Benton, and D. Gabriel. 2010. Comparing organic farming and land sparing: optimizing yield and butterfly populations at a landscape scale. Ecology Letters 13(11):1358-1367. International Assessment of Agricultural Knowledge, Science and Technology for Development. 2008. Available at http://www.agassessment.org/index.cfm?Page=IAASTD%20Reports&ItemID=2713. Klein, A. M., B. E. Vaissiere, J. H. Cane, I. Steffan-Dewenter, S. A. Cunningham, C. Kremen, and T. Tscharntke. 2007. Importance of pollinators in changing landscapes for world crops. Proceedings of the Royal Society B-Biological Sciences 274(1608):303-313. Landis, D. A., M. M. Gardiner, W. van der Werf, and S. M. Swinton. 2008. Increasing corn for biofuel production reduces biocontrol services in agricultural landscapes. Proceedings of the National Academy of Sciences of the United States of America 105(51):20552-20557. Lobell, D. B., M. B. Burke, C. Tebaldi, M. C. Mastrandrea, W. P. Falcon, and R. L. Naylor. 2008 Prioritizing climate change adaptation needs for food security in 2030. Science 319:607-610. Parfitt, J., M. Barthel, and S. Macnaughton. 2010. Food waste within food supply chains: quantification and potential for change to 2050. Philosophical Transactions of the Royal Society B: Biological Sciences 365(1554):3065-3081. Ricketts, T. H., G. C. Daily, P. R. Ehrlich, and C. D. Michener. 2004 Economic value of tropical forest to coffee production. Proceedings of the National Academy of Sciences of the United States of America 101:12579-12582. Smith, P., P. J. Gregory, D. van Vuuren, M. Obersteiner, P. Havlik, M. Rounsevell, J. Woods, E. Stehfest, and J. Bellarby. 2010. Competition for land. Philosophical Transactions of the Royal Society B-Biological Sciences 365:2941-2957. TEEB. 2010. The Economics of Ecosystems and Biodiversity: Mainstreaming the Economics of Nature: A synthesis of the approach, conclusions and recommendations of TEEB. Marta: Progress Press. UK Foresight Programme. 2011. The Future of Food and Farming: Challenges and Choices for Global Sustainability. Available at http://www.bis.gov.uk/assets/bispartners/foresight/docs/food-and-farming/11-546-future-of-food-and-farming-report.pdf. United Nations. 2011. Agroecology and the Right to Food. Report presented at the 16th Session of the United Nations Human Rights Council. A/HRC/16/49. Vandermeer, J., I. Perfecto, and S. M. Philpott. 2008 Clusters of ant colonies and robust criticality in a tropical agroecosystem. Nature 451:457-U3. Vandermeer, J., I. Perfecto, and H. Liere. 2009 Evidence for hyperparasitism of coffee rust (Hemileia vastatrix) by the entomogenous fungus, lecanicillium lecanii, through a complex ecological web. Plant Pathology 58:636-641. Vandermeer, J., I. Perfecto, and S. M. Philpott. 2010 Ecological complexity and pest control in organic coffee production: uncovering an autonomous ecosystem service. Bioscience 60:527-537. Vitousek, P. M., R. Naylor, T. Crews, M. B. David, L. E. Drinkwater, E. Holland, P. J. Johnes, J. Katzenberger, L. A. Martinelli, P. A. Matson, G. Nziguheba, D. Ojima, C. A. Palm, G. P. Robertson, P. A. Sanchez, A. R. Townsend, and F. S. Zhang. 2009 Nutrient Imbalances in Agricultural Development. Science 324:1519-1520.
OCR for page 164
A Sustainability Challenge: Food Security for All von Witzke, H. and S. Noleppa. 2010. EU agricultural production and trade: Can more efficiency prevent increasing land-grabbing outside of Europe? Research Report. University of Piacenca. Weber, C. L. and H. S. Matthews. 2008 Food-miles and the relative climate impacts of food choices in the united states. Environmental Science & Technology 42:3508-3513. World Commission on Environment and Development. 1987. Our Common Future. New York: Oxford University. Lobell Ainsworth, E. A., A. D. B. Leakey, D. R. Ort, and S. P. Long. 2008. FACE-ing the facts: inconsistencies and interdependence among field, chamber and modeling studies of elevated CO2 impacts on crop yield and food supply. New Phytologist 179(1):5-9. Lobell, D. B., M. Banziger, C. Magorokosho, and B. Vivek. 2011. Nonlinear heat effects on African maize as evidenced by historical yield trials. Nature Climate Change 1(1):42-45. Lobell, D. B., W. S. Schlenker, and J. Costa-Roberts. 2011. Climate trends and global food production since 1980. Science 333(6042):616-620. Schlenker, W. and M. J. Roberts. 2009. Nonlinear temperature effects indicate severe damages to U.S. crop yields under climate change. Proceedings of the National Academy of Sciences 106(37):15594-15598. Schlenker, W. and D. B. Lobell. 2010. Robust negative impacts of climate change on African agriculture. Environmental Research Letters 014010:8. Tubiello, F. N., J. S. Amthor, K. J. Boote, M. Donatelli, W. Easterling, G. Fischer, R. M. Gifford, M. Howden, J. Reilly, and C. Rosenzweig. 2007. Crop response to elevated CO2 and world food supply: A comment on “Food for Thought.” by Long et al. Science 312:1918-1921. 2006. European Journal of Agronomy 26(3):215-223.