Four degrees and beyond: the potential for a global ... - Amper

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Downloaded from rsta.royalsocietypublishing.org on November 30, 2010 Phil. Trans. R. Soc. A (2011) 369, 117–136 doi:10.1098/rsta.2010.0246 Agriculture and food systems in sub-Saharan Africa in a 4 ◦ C+ world BY PHILIP K. THORNTON 1, *, PETER G. JONES 2 ,POLLY J. ERICKSEN 3,† AND ANDREW J. CHALLINOR 4 1 CGIAR/ESSP Program on Climate Change, Agriculture and Food Security (CCAFS ), International Livestock Research Institute (ILRI ), PO Box 30709, Nairobi 00100, Kenya 2 Waen Associates, Y Waen, Islaw’r Dref, Dolgellau, Gwynedd LL40 1TS, Wales, UK 3 Global Environmental Change and Food Systems (GECAFS ) Programme, Environmental Change Institute, Oxford University Centre for the Environment, South Parks Road, Oxford OX1 3QY, UK 4 Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK Agricultural development in sub-Saharan Africa faces daunting challenges, which climate change and increasing climate variability will compound in vulnerable areas. The impacts of a changing climate on agricultural production in a world that warms by 4 ◦ C or more are likely to be severe in places. The livelihoods of many croppers and livestock keepers in Africa are associated with diversity of options. The changes in crop and livestock production that are likely to result in a 4 ◦ C+ world will diminish the options available to most smallholders. In such a world, current crop and livestock varieties and agricultural practices will often be inadequate, and food security will be more difficult to achieve because of commodity price increases and local production shortfalls. While adaptation strategies exist, considerable institutional and policy support will be needed to implement them successfully on the scale required. Even in the 2 ◦ C+ world that appears inevitable, planning for and implementing successful adaptation strategies are critical if agricultural growth in the region is to occur, food security be achieved and household livelihoods be enhanced. As part of this effort, better understanding of the critical thresholds in global and African food systems requires urgent research. Keywords: food security; adaptation; climate change; livelihoods *Author for correspondence (p.thornton@cgiar.org). † Present address: International Livestock Research Institute (ILRI), PO Box 30709, Nairobi 00100, Kenya. One contribution of 13 to a Theme Issue ‘Four degrees and beyond: the potential for a global temperature increase of four degrees and its implications’. 117 This journal is © 2011 The Royal Society
118 P. K. Thornton et al. 1. Introduction Agricultural and food systems globally face considerable challenges in the coming decades. The demand for food continues to increase rapidly, as a result of various drivers. Current estimates of human population in 2050 range from 7.96 billion to 10.46 billion; the medium variant estimate is 9.19 billion [1]. Continued population growth could be a significant impediment to achieving improvements in food security in some countries, even as world population stabilizes sometime during the present century. Food demand is also strongly affected by urbanization. More people now live in urban settings than in rural areas. The next few decades will see unprecedented urban growth particularly in Africa and Asia. Urbanization has considerable impact on patterns of food consumption [2], but it is not necessarily associated with a reduction in food insecurity. Recent data from southern Africa indicate both chronic poverty and food insecurity in a survey of 11 cities [3]. A third key driver affecting food demand is income growth. Between 1950 and 2000, world per capita income grew at an annual rate of 2.1 per cent [4]. As income grows, patterns of food expenditure change, often to more meats, fats and sugar [5]. Projections of future economic growth vary considerably, but it is expected to continue. Fourth, the agricultural production sector is catering increasingly to globalized diets. Retailing through supermarkets is growing at 20 per cent per annum in some countries, and this growth is likely to continue over the next few decades as urban consumers demand more processed foods, shifting agricultural production systems from on-farm production towards agribusiness chains [6]. Several projections suggest that global cereal and livestock production may need to increase by between 60 and 100 per cent to 2050, depending on the scenario, because of the increasing demand and changing patterns of demand [7]. In sub-Saharan Africa (SSA), this will require considerable investments in agricultural research and technology and in infrastructural development [6]. Agricultural growth rates for SSA declined in the 2000s [8] and food insecurity is still a concern, as the prevalence of malnourishment has only dropped from 34 to 30 per cent in two decades [9]. Agriculture is still an economic mainstay of many SSA countries, employing about 60 per cent of the workforce and contributing an average of 30 per cent of gross domestic product [10]. Although the efforts of the agricultural research and development communities over the last 40 years have led to successes in improving yields, increasing incomes and contributing to food security, these successes have not been automatic and they have not occurred everywhere [11]. Rural communities and households continue to demonstrate tremendous adaptive capacity in the face of economic and social change, but this capacity needs appropriate social, institutional and political support [12]. Even more challenging, the necessary increases in food production will have to occur at the same time as the climate is changing and as climate variability increases. Potential impacts of climate change on agricultural production in SSA have been assessed in several modelling studies, using methods grounded in an understanding of both crop and climate science (see the review by Challinor et al. [13]). The inherent complexity of the climate–crop system, together with fundamental limits to climate predictability, mean that predicted ranges for major crops depend strongly on the methods and models used [14]. However, as in the current climate, these broad trends are likely to mask local differences caused Phil. Trans. R. Soc. A (2011) Downloaded from rsta.royalsocietypublishing.org on November 30, 2010
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ISSN 1364-503X volume 369 number 19
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Phil. Trans. R. Soc. A (2011) 369,
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Editorial David Garner Phil. Trans.
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Four degrees and beyond: the potent
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Preface 5 commitments might give us
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8 M. New et al. In the final plenar
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16 M. New et al. as permanent crop
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Beyond 'dangerous' climate change:
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Beyond dangerous climate change 21
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Cumulative carbon emissions, emissi
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REVIEW Phil. Trans. R. Soc. A (2011
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Review. Interactions in a 4 ◦ C w
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spread in mosquitoborne disease may
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[89,94,95] further acidification by
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Editorial Editorial 3 D. Garner Pre
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