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Adaptation of Gambian Agriculture to Climate Change: Novel or re-discovered strategies Prepared by the AF47 team Momodou Njie, Molly Hellmuth, Peter Droogers, Bubu Jallow, John Mac Callaway, Bernard Gomez and presented at the Second AIACC Regional Workshop for Africa and Indian Ocean Islands 24 – 27 March 2004 Hotel Ngor Diarama, Dakar, Senegal Relevance pre-1970 current distant future 0.30 probab. (%) 0.25 0.20 0.15 0.10 0.05 0.00 0 500 1000 Percentage occurrence of rainfall rainfall (mm) < 600mm < 1000mm pre-1970 3.0 35.7 current 9.1 90.9 future 80.8 99.5 1500 2000 Approach • Literature review • Collection of physical and socio-economic data • Qualitative assessment of coping/adaptation strategies • Crop modelling • Benefit-cost and economic analyses Some GCM results Yundum ECHAM4_A2 42 42 40 40 Max. Temp. (oC) Max. Temp. (oC) Yundum HadCM3_A2 38 36 34 38 36 34 32 32 30 30 OBS GCM 1961- 2010- 20701990 2039 2099 OBS GCM 1961- 2010- 20701990 2039 2099 More GCM results 2000 Precipitation (mm y-1) Precipitation (mm y-1) 2000 1600 1200 800 400 1600 1200 800 400 0 0 OBS GCM 1961- 2010- 20701990 2039 2099 Yundum HadCM3_A2 OBS GCM 1961- 2010- 20701990 2039 2099 Yundum ECHAM4_A2 Qualitative Assessment of Traditional Coping/Strategies Strategy Constraint(s)/Uncertainties 1 Crop diversification and selection 50% decrease in mean rainfall 50% increase in standard deviation (HadCM3_A2) 2 Plot dispersal 50% decline in per capita availability of prime land (< 5ha/dabada by 2025) 3 Sale of assets (raising cash) 40 – 50 % of dabadas possess livestock 4 Relief food aid trends, social support networks 5 Shift in main food sources Adaptation Strategies identified in The Gambia’s INC Strategy 1 Introduction of new crops 2 Extensification of most hardy crops 3 Development of irrigated agriculture 4 Shifting planting dates 5 Reduction of post-harvest losses Remarks A re-statement of crop selection Fundamental changes to traditional production systems Adaptation Strategies investigated by A47 Strategy Rationale 1 Introduction of new crops Expected decline in rainfall, and increased variability 2 Soil fertilisation Expected decrease in prime land availability, degradation of arable land (assume 2% per decade), and availability of land which require some amendments (14%, second largest class of agriculturally suitable land) 3 Irrigation Expected changes in rainfall patterns, and increased variability, possibility of extending growing season and expanding cultivated area,water availability (ground and surface water) Analytical Framework Social/Political acceptability Climate Scenarios (SRES) RegCM/Downscaling Socioeconomic Scenarios Land & Water Resources Crop Model Crop Production Benefits and Costs Adaptation Options Crop Modelling Radiation Light interception Potential photosynthesis Water and/or salt stress Actual photosynthesis Maintenance respiration SWAP-WOFOST Leaf area Dry matter increase Partitioning Roots Death (alive) Death Stems (alive) Growth respiration Storage organs Leaves (alive) (alive) Death Crop Modelling Results Distant Future (2070 – 2099) average (kg ha-1) No adaptation Crop variety Fertilizer Irrigation Supplemental Irr. 1069 1327 1480 1702 1250 Yield change (%) +24 +38 +59 +17 CV (%) 50 34 38 10 37 Macroeconomic Analyses (1) Stock-to-utilisation ratio = 20% Base Case Frequency of crisis years Food Aid & Commercial Imports CC No Adaptation CC + Irrigation 4/30 30/30 25/30 $60,623,069 $4,158,558,131 $357,015,844 Stock-to-utilisation ratio = 0% Base Case Frequency of crisis years Food Aid & Commercial Imports CC No Adaptation CC + Irrigation 3/30 30/30 21/30 $24,477,446 $3,965,637,162 $188,394,342 Macroeconomic Analyses (2) STU ratio = 0 % STU ratio = 20 % Remarks CC damages $3,941,159,716 $4,097,935,062 Food Aid/Import Bill with CC and no adaptation vis-à-vis Base Case Project benefits $3,777,242,820 $3,801,542,287 Food Aid/Import Bill with CC and Irrigation vis-à-vis CC and No Adaptation Net project benefits $3,739,616,047 $3,763,915,514 Project benefits less project costs Imposed CC damages $201,543,669 $334,019,546 Climate change damages less net project benefits Microeconomic Analyses Yield response for different WUEs high WUE 500 2.0 high WUE low WUE B/C = 1 low WUE 400 1.5 300 B/C yield increase (kg/ha) 1m3= $0.31 1.0 200 0.5 100 0.0 0 0 100 200 300 400 0 500 100 200 300 1m3= $0.12 1m3= $0.05 high WUE 2.0 high WUE 2.0 low WUE low WUE B/C = 1 1.0 1.0 0.5 0.5 0.0 0.0 200 300 Irrigation (mm) 400 B/C = 1 1.5 B/C B/C 1.5 100 500 Irrigation (mm) irrigation (mm) 0 400 500 0 100 200 300 Irrigation (mm) 400 500 Work to be done • Evaluate benefits of conjunctive use of surface and groundwater • Develop future socio-economic scenarios • Detailed/refined economic analyses THANKS FOR YOUR KIND ATTENTION