Big Facts on Climate Change, Agriculture and Food Security

Crops and Farming Systems

  • As climate change progresses, it is increasingly likely that current cropping systems will no longer be viable in many locations. In Africa, for example, maize cultivation will no longer be viable across up to 3% of the continent under either higher (A1) or lower (B1) emissions scenarios. These areas, which support 35 million people at present, are expected to switch from mixed crop–livestock systems to livestock only (Jones and Thornton 2009).
  • Changing patterns of pests and diseases will call for an increased focus on integrated management systems (Herrera et al. 2011).
  • Global climate models (GCMs) have become increasingly important for climate change science and provide the basis for most impact studies. Since impact models are highly sensitive to input climate data, GCM skill is crucial for getting better short-, medium- and long-term outlooks for agricultural production and food security. At least 5–30 years of work is required to improve regional temperature simulations and at least 30–50 years for sufficiently accurate regional precipitation simulations before these can be directly input into impact models (Ramirez-Villegas et al. 2013).
  • A number of processes linked to climate change will impact agricultural productivity. Agricultural productivity is expected to increase slightly in future at mid- to high latitudes, while decreases are expected in tropical regions (Easterling et al. 2007).
  • Uncertainties in projections limit the value of precise numerical forecasts of future crop yields; all projections of future crop yields and associated changes in food prices should be treated with considerable caution (Challinor et al. 2009).
  • Historical studies demonstrate that climate change has already had negative impacts on crop yields. Maize, wheat and other major crops have experienced significant climate-associated yield reductions of 40 million tonnes per year from 1981 to 2002 at the global level (Lobell and Field 2007).
  • Rice: Climate change may have a positive impact on rice production in some areas, by allowing rice production in more northern regions, such as China, or increasing the length of growing season to allow for a second rice crop. Elsewhere, however, production is expected to decline. The International Food Policy Research Institute's IMPACT model, for example, projects that that rice productivity will decline by 14% in South Asia, 10% in East Asia and the Pacific and 15% in sub-Saharan Africa by 2050. This would result in price increases of between 32% and 37% (Nelson et al. 2009).
  • Wheat: Given the climatic conditions expected to prevail in 2050, it is predicted that the mega-environment for wheat in South Asia’s Indo-Gangetic Plain (which produces about 15% of the world’s wheat) will shrink by just over half. This will mainly be due to increased heat stress, which will result in major reductions in wheat harvest. This will threaten the food security of around 200 million people (CGIAR 2009). The IFPRI IMPACT model, for example, projects changes in wheat yields of between −34.3 and +9.7% between 2000 and 2050 (Nelson et al. 2009).
  • Potato: The International Potato Center (CIP) has modelled the effect of climate change on potato production to 2069 (Hijmans 2003). This indicates that potential yield will decrease 18%–32% without adaptation and by 9%–18% with adaptation and that shifting of planting time and location will be less feasible at low latitudes than at high latitudes (where expected changes in yield are relatively small), resulting in large reductions in production.
  • Maize: Jones and Thornton (2003) projected a reduction of around 10% in maize production in Africa and Latin America under various climate scenarios to 2055, corresponding to losses of USD 2 billion per year. The IFPRI IMPACT model projects that maize yields (irrigated and rainfed) will change by −8.7% to +9.5% between 2000 and 2050 (Nelson et al. 2009).
  • Global aggregate figures mask major spatial and temporal variability. In 2030, for example, using a mean of two climate models and two climate scenarios, maize production is projected to increase by 18% in Kenya but fall by 9% in Uganda. Within these countries, there is further variability between agro-ecological zones (Thornton et al. 2010).
  • Changing temperatures and precipitation regimes will likely cause local extinctions of crop wild relatives as suitable natural ecosystems will decrease or disappear (Jarvis et al. 2008).
  • Changes in yields of rainfed crops will be driven by changes in both precipitation and temperature, while changes in yields on irrigated land will be driven by temperature changes alone. The impact of climate change on rainfed wheat, rice and maize is expected to be lower than on irrigated crops because climate change will reduce availability of water for irrigation (Nelson et al. 2009).
  • It is expected that shifts in crop climates to 2050 will result in many countries facing novel climates that are currently not found within their boundaries (Jarvis et al. 2011). A significant percentage of these new crop-climates will have analogues in at least five other countries, stressing the need of international movement of germplasm (Burke et al. 2009).
  • The global area suitable for growing coffee crops is expected to diminish to 50% of the current area by 2050 due to climate change. The highest impacts will be suffered at low latitudes and altitudes, particularly in Brazil, India and Nicaragua (Bunn et al. 2015a, b).
Sources and further reading
  • Alexandratos N. 2011. Critical evaluation of selected projections. In: Piero Conforti, ed. Looking ahead in world food and agriculture: perspectives to 2050. Rome: Food and Agriculture Organization of the United Nations. (Available from (Accessed on 7 November 2013)
  • Bunn C, Läderach P, Pérez JG, Montagnon C, Schilling T. 2015b. Multiclass classification of agro-ecological zones for arabica Coffee: an improved understanding of the impacts of climate change. PLoS One 10(10):e0140490.
  • Bunn C, Läderach P, Ovalle Rivera O, Kirschke D. 2015a. A bitter cup: climate change profile of global production of Arabica and Robusta coffee. Climatic Change 129(1): 89-101.
  • Burke MB, Lobell DB, Guarino L. 2009. Shifts in African crop climates by 2050, and the implications for crop improvement and genetic resources conservation. Global Environmental Change 19(3):317–325. (Available from
  • CGIAR. 2009. Mapping the menace of global climate change. Washington, DC: CGIAR. (Available from (Accessed on 7 November 2013)
  • Challinor AJ, Ewert F, Arnold S, Simelton E, Fraser E. 2009. Crops and climate change: progress, trends, and challenges in simulating impacts and informing adaptation. Journal of Experimental Botany 60(10):2775–2789. (Available from
  • Easterling WE, Aggarwal PK, Batima P, Brander KM, Erda L, Howden SM, Kirilenko A, Morton J, Soussana J-F, Schmidhuber J, Tubiello FN. 2007. Food, fibre and forest products. In: Parry ML, Canziani OF, Palutikof JP, Van Der Linden PJ, Hanson CE, eds. Climate change 2007: Impacts, adaptation and vulnerability. Contribution of Working Group II to the fourth assessment report of the Intergovernmental Panel on Climate Change. Cambridge, UK: Cambridge University Press. (Available from
  • Herrera B, Hyman G, Belloti A. 2011. Threats to cassava production: known and potential geographic distribution of four key biotic constraints. Food Security 3(3):329–345. (Available from
  • Hijmans RJ. 2003. The effect of climate change on global potato production. American Journal of Potato Research 80:271–280. (Available from
  • Jarvis A, Lane A, Hijmans R. 2008.The effect of climate change on crop wild relatives. Agriculture, Ecosystem & Environment 126(1–2):13–23. (Available from
  • Jarvis A, Upadhaya H, Gowda CLL, Aggarwal PK, Fujisaka S, Anderson B. 2011. Climate change and its effect on conservation and use of plant genetic resources for food and agriculture and associated biodiversity for food security. Thematic background study. (Available from (Accessed on 7 November 2013)
  • Jones PG, Thornton PK. 2003. The potential impacts of climate change in tropical agriculture: the case of maize in Africa and Latin America in 2055. Global Environmental Change 13:51–59. (Available from
  • Jones PG, Thornton PK. 2009. Croppers to livestock keepers: livelihood transitions to 2050 in Africa due to climate change. Environmental Science & Policy 12(4):427–437. (Available from
  • Lobell DB, Field CB. 2007. Global scale climate–crop yield relationships and the impacts of recent warming. Environmental Research Letters 2:1–7. (Available from (Accessed on 7 November 2013)
  • Nelson GC, Rosegrant MW, Koo J, Robertson R, Sulser T, Zhu T, Ringler C, Msangi S, Palazzo A, Batka M, Magalhaes M, Valmonte-Santos R, Ewing M, Lee D. 2009. Climate change: Impact on agriculture and costs of adaptation. Washington, DC: International Food Policy Research Institute. (Available from (Accessed on 7 November 2013)
  • Parry ML, Canziani OF, Palutikof JP, van der Linden PJ, Hanson CE, eds. 2007. Climate change 2007: Impacts, adaptation and vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK: Cambridge University Press. (Available from
  • Ramirez-Villegas J, Challinor AJ, Thornton PK, Jarvis A. 2013. Implications of regional improvement in global climate models for agricultural impact research. Environmental Research Letters 8(2):024018 (Available from (Accessed on 7 November 2013)
  • Thornton PK, Jones PG, Alagarswamy G, Andresen J, Herrero M. 2010. Adapting to climate change: agricultural system and household impacts in East Africa. Agricultural Systems 103:73–82. (Available from