K1 IMPLICATIONS OF CLIMATE CHANGE FOR AGRICULTURE, FOOD SUPPLY AND RISK OF HUNGER

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1 K1 IMPLICATIONS OF CLIMATE CHANGE FOR AGRICULTURE, FOOD SUPPLY AND RISK OF HUNGER Martin Parry Centre for Environmental Policy, Imperial College London London SW7 2AZ. ABSTRACT This paper reviews the series of studies, from 1994 to 27, which have evaluated the potential effects of climate change on crop yield, food production and risk of hunger. There are two global studies of crop yield responses and several additional estimates of production that are based on the first of these. The studies cover three broad types of analysis: 1) effects under climate change but with underlying socio-economic characteristics largely unspecified, 2) effects under both changes in climate and with varying development pathways assumed to affect underlying socio-economics, and 3) effects under different policies of stabilisation of greenhouse gases. There are some conclusions common to all studies: that climate change will generally reduce production potential and increase risk of hunger, and that Africa is the most adversely affected region. An additionally important initial conclusion is that pathways of sustainable economic development have a marked effect in reducing the adverse effects on climate change. KEYWORDS Climate change, agriculture, food supply, crop yields, food prices, risk of hunger REFERENCES Rosenzweig, C. and Parry, M.L Potential impacts of climate change on world food supply. Nature Vol. 367, pp Parry M.L., C. Rosenzweig, A. Iglesias, G. Fischer, and M.T.J. Livermore 1999a. Climate change and world food security: a new assessment In: Parry and Livermore (Eds.) A new assessment of the global effects of climate change Global Environmental Change, Vol. 9 (Supplemental Issue) pp.s52-s67. Arnell, N.W., Cannell, M.G.R., Hulme, M., Kovats, R.S., Mitchell, J.F.B., Nicholls, R.J., Parry, M.L., Livermore, M.T.J. and White, A. 21. The consequences of CO 2 stabilisation for the impacts of climate change. Climatic Change. 12, Parry, M.L., Rosenzweig, C., Iglesias, A., Livermore, M. and Fischer, G. 24. Effects of climate change on global food production under SRES emissions and socio-economic scenarios. Global Environmental Change. 14(1), Fischer, G, Shah, M., and Velthuizen, H. 22. Climate Change and Agricultural Vulnerability. Vienna: International Institute for Applied Systems Analysis. Cline, W.R. 27. Global Warming and Agriculture: Impact estimates by country. Washington DC: Center for Global Development. IPCC. 27. Climate Change 27: Impacts, Adaptation and Vulnerability- Contribution of Working Group II to the IPCC Fourth Assessment, Eds Parry, M.L. et al, Cambridge University Press, Cambridge. Easterling, W. and Aggarwal, P., 27 Food, fibre and forest products, in: Climate Change 27: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. M.L.Parry, O.F.Canzianai, J.P.Palutikof, P.J.van der Linden and C.E.Hanson, Cambridge: Cam,brisge University Press, U.K.,

2 OUTLINE Implications of climate change for agriculture, food supply and risk of hunger Martin Parry Centre for Environmental Policy, Imperial College London [Co-Chair, IPCC WGII, 27 Assessment] The projected changes of climate The effects on food supply and risk of hunger Potential responses: mitigate emissions, adapt agriculture. Conclusions Anthropogenic warming is unequivocal Projected changes in temperature are as projected in IPCC Third Assessment (21), but uncertainty range is greater and upper end is higher Most key impacts stem from reduced water availability. Projected changes (%) in run-off, 21st century. White areas are where less than two-thirds of models agree, hatched are where 9% of models agree (IPCC SYR) Availability of irrigation water Scholze et al. (26) Blue tendency to increase Red tendency to decrease -22-

3 Rainfall intensities may also change: eg Projected increase in intensity of Indian monsoon, c. 25 (HadRM2) Change in Annual number of rainy days Change in rainfall per rainy day Changes in Drought Severity. HadCM3 A2 scenario (Burke and Brown, 27) Other projected changes of climate (by 21) Sea levels will rise.1 to.8 metres More tropical cyclones More frequent very hot days And we can see some of these changes already, occurring now. Studies of climate, food supply and risk of hunger: 3 sets of futures: A. Single business-as-usual future B. Range of alternative development pathways C. Future with GHG reductions 3 approaches to estimation: 1) crop modelling of yields 2) spatial shift of crop suitability 3) Ricardian economic analysis of land-use response Crop yields will generally decrease, but there may be increases in temperate regions for up to +2deg C The projection of effects on food supply: A). For single business-as-usual future. 1) By crop yield modelling (Rosenzweig and Parry, 1995 et seq) Crop yield models (IBSNAT/DSSAT) run for 118 sites Yield responses extrapolated across all cropping zones, world-wide Yield changes input to world food model (the Basic Linked System) Output: production, prices, risk of hunger -23-

4 Crop yield change: 21, 25, 28 Cereal production (mmt) Reference Climate change scenario scenario 22s 28s 22s 28s 25s 25s % change in prices from 199 baseline s 25s 28s Projected global cereal production for reference case and the climate change scenario. Percentage change in global cereal prices under the climate change scenario ( = reference case). Additional millions of people at risk of hunger s 25s 28s Additional people at risk of hunger ( = reference case, i.e. about 3 million in 2, FAO ). Percentage change in average crop yields. Effects of CO 2 are taken into account. Crops modelled are: wheat, maize and rice. (Rosenzweig/ Parry, 1995) Cereal production (mmt) Additional millions of people at risk of hunger Reference Climate change scenario scenario Africa 22s 25s 28s Africa 22s 25s 28s 22s 25s 28s Projections for cereal production in Africa under the reference case and the climate change scenario Additional number of people at risk of hunger in Africa under the climate change scenario ( = Projected reference case). Projecting shifts of agroecological zones (Fischer, et al. 2) Changes in length of growing season Shift of zones of crop suitability Estimation of altered yields Altered yields in BLS world food model Undefined SI > 75 : Very high SI > 63 : High SI > 5 : Good SI > 35 : Medium SI > 2 : Moderate SI > 5 : Marginal SI > : Very marginal Not suitable Water Suitability for rain-fed cereals (reference climate, ). Undefined > 5 % 2 to 5 % 5 to 2 % -5 to 5 % -2 to -5 % -5 to -2 % < -5 % Not assessed Water Country-level impacts on rain-fed cereals, currently cultivated land (HadCM3-A1FI, 28s) Change in suitability for rain-fed cereals (HadCM3-A1FI, 28s). Undefined > 5 % 2 to 5 % 5 to 2 % -5 to 5 % -2 to -5 % -5 to -2 % < -5 % Not assessed Water Country-level impacts on rain-fed cereals, currently cultivated land (CSIRO-A2, 28s). -24-

5 Sub-Saharan land with no or slight environmental constraints 3. Finally, allowing for: Shifts of land to highest value uses (W. Kline, 26) Yields changes with CO2 effects [Cline,27] All economic models suggest prices will rise, but there is uncertainty about when this may occur B. FUTURES THAT INCLUDE DIFFERENT PATHWAYS OF DEVELOPMENT ( IPCC s SRES scenarios) 6 5 SRES A1 SRES A2 SRES B1 SRES B2 A1 = World of Global Markets: high growth, high tech, low pop, A2 = World of Regional Enterprise: high pop (11bn in 25), high growth (but inequitable) [current pathway] B1 = World of Global Sustainability: low pop, moderate growth, global environmental agreements B2 = World of Local Stewardship: low pop (9 bn in 25), moderate growth, local envt management Million Metric Tonnes Year Future reference case estimates of cereal production under the four SRES marker scenarios (no climate change). Parry, Rosenzweig, Fischer, 2-25-

6 Change in cereal prices (%) SRES A1 SRES A2 SRES B1 SRES B2 Additional millions of people Year Future reference case global cereal prices, relative to 199 prices, for the four SRES marker scenarios (no climate change) Year SRES A1 SRES A2 SRES B1 SRES B2 Future reference case estimates of the numbers of people at risk of hunger, for the four SRES marker scenarios (no climate change). Parry, Rosenzweig, Fischer,,2 With projected climate change- induced shortfall in global cereal production: A2 and B2 pathways Projected climate change- induced Additional People at Risk of Hunger Million Metric Tonnes (mmt) Additional Millions of People A2 - Regional Enterprise B2 - Local Stewardship A2 - Regional Enterprise B2 - Local Stewardship C. Impacts under a future of emissions mitigation Emissions + concentrations CO 2 from unmitigated and stabilising emission scenarios 2 1 Changes in runoff from the present day to the 28s Unmitigated emissions 95 Anthropogenic CO 2 emissions (GtC/yr) CO 2 concentration (ppm) N. Arnell Unmitigated emissions 75 ppm stabilisation 55 ppm stabilisation Hadley Centre for Climate Prediction and Research Stabilisation of CO 2 at 75 ppm Change in annual runoff (%) Stabilisation of CO 2 at 55 ppm to

7 Potential change in cereal yields (%) Changes in crop yield from the present day to the 28s CONCLUSION: The extent of the challenge for adaptation No data Parry et al, 21 Unmitigated emissions Stabilisation of CO 2 at 75 ppm Stabilisation of CO 2 at 55 ppm Global impacts by sector (IPCC Technical Summary) Impacts by region (IPCC Technical Summary) Committed.6 o C 2. o C target (pre-ind.) -27-

8 5 per cent cuts in emissions by 25 8 per cent cuts in emissions by

9 Conclusions : 1 Climate change is likely globally to : reduce potential agricultural output in the longer term, and increase risk of hunger. Adverse effects, regionally and near-term, are likely to be marked in the dry tropics and dry sub-tropics (eg especially in Africa) Conclusions : 2 Most serious effects, sub-nationally, will probably be at the social and economic margins (where adaptive capacity is low). Early mitigation is needed (with emissions peaking by c.215) so that adaptive capacity is not exceeded by subsequent large climate changes Emissions need to be cut by c. 8% (of 199 levels) by 25 to avoid serious damage Conclusions : 3 A combination of adaptation and mitigation is necessary. Especially adaptation to increase resilience to climate change: a) technology (incl. crop breeding for new climates, eg drought-proofing; rural electrification ), b) management (eg farming systems that use water more efficiently), c) institutions (eg changes to market and tariff structure). Many adaptations can be win-win (eg droughtproofing for present weather can increase resilience to effects of a long-term drying trend). Adapting agriculture to climate change New crop varieties: eg drought and heat resistant crops ( either by traditional plant breeding, or genetic modification); Irrigation: needs rural electrification (especially in Africa= a Millenium Development Goal) Shift of cropping zones: eg northwards in N. Hemisphere (but limited by soils) Reform global food system: [today, enough food is produced for all, but still 5m are hungry] Conclusions : 4 Need to foster adaptation in most vulnerable regions: the poorest areas, small islands, low-lying coasts, and dry/semi-arid regions. THANK YOU! Should we concentrate more on non-optimising objectives? eg reducing risk, minimising yield reductions in drought years, developing resilient crop varieties and crop mixes; rather than maximising output. Regardless adaptation is needed now. -29-