Using Global Static CGE to Assess the Effects of Climate Volatility
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The presentation discusses the assessment of climate volatility impacts on agriculture and poverty using a global static CGE model. It highlights how extreme climate events adversely affect agricultural output, particularly in tropical and subtropical regions, leading to increased food insecurity and poverty. Key findings include the ambiguous effects of agricultural commodity price fluctuations on rural incomes and the significant historical volatility in grain production and pricing in countries like Tanzania.
Using Global Static CGE to Assess the Effects of Climate Volatility
- 1. Using Global Static CGE to Assess the Effects of Climate Volatility Presented by: Amer Ahmed, World Bank www.agrodep.org AGRODEP Workshop on Analytical Tools for Climate Change Analysis June 6-7, 2011 • Dakar, Senegal Please check the latest version of this presentation on: http://agrodep.cgxchange.org/first-annual-workshop
- 2. Using Global Static CGE to Assess the Effects of Climate Volatility Amer Ahmed World Bank June 7, 2011 AGRODEP Members’ Meeting and Workshop Dakar, Senegal
- 3. Objectives • Motivation: climate volatility, agricultural variability, & poverty • Why CGE? – GE effects – Illustration through mechanisms affecting poverty • Implications of simulation design • Illustrations from recent research – Ahmed, Diffenbaugh, & Hertel. (2009, ERL) – Ahmed, Diffenbaugh, Hertel, Lobell, Ramankutty, Rios, & Rowhani (2011, GEC) 2
- 4. Climate Volatility & Poverty • Extreme climate events will reduce agricultural output in the tropics and subtropics (Lobell et al, 2008; Battisti and Naylor, 2009) • Food insecurity • Food insecurity influenced by forces that constrain people’s access to food, not just availability (Sen, 1981) • Income & price effects 3
- 5. Income Effects • Changes to household income depend on sources of income • For many rural poor, main endowment is unskilled labor • Agriculture is unskilled labor intensive – If output expands, unskilled wages rise; opposite for contraction • Ambiguous impact of agricultural commodity price rise on non-farm rural households – depends on earnings diversification, impacts on farm factor returns, and unskilled wages 4
- 6. Price Effects • Higher crop prices hurt all households, but hurt the poor relatively more due to large food budget share • Lower crop prices may reduce incomes of rural net-sellers of crops • Recent experience: 100 million additional poor due to global food price crisis between 2005-2008 (Ivanic & Martin, 2009) 5
- 7. Historical Volatility* in Grains Production and Prices in Tanzania Prices more volatile than production 6 *Volatility = standard deviation of interannual % changes Source: Ahmed , Diffenbaugh, & Hertel (2009)
- 8. Historical Volatility* in Grains Production and Prices in Tanzania Prices more volatile than production 1 in 30 productivity draw from here 7 *Volatility = standard deviation of interannual % changes Source: Ahmed , Diffenbaugh, & Hertel (2009)
- 9. Computational Framework • GTAP model used to elicit national price and earnings impacts of productivity shocks : – land use by Agro-Ecological Zone – factor market segmentation • Micro-simulation module to evaluate household-level impacts at poverty line in 7 population strata across 16 countries in Asia, Latin America and Africa • Survey data: – Estimate earnings shares and density around poverty line – Use estimated consumer demand system to predict consumption changes at poverty line – Estimate change in stratum poverty due to combination of factor earnings and consumption impacts – Combine into estimate of national poverty using shares of strata in national poverty headcount 8
- 10. Simulation Design • Shocking Grains productivity => interannual production changes • Short run – Labor only mobile factor – Farmers have limited ability to react • Shocking one country at a time from 2001 benchmark – Sensitivity analysis, NOT forecast 9
- 11. Impact on Poverty Rates of 1 in 30 Climate Extreme 1 in 30 draw worsens poverty 10 Source: Ahmed , Diffenbaugh, & Hertel (2009)
- 12. %D in Poverty by Household Stratum due to 1 in 30 Climate Extreme Table 2: Percent change in poverty due to once-in-30 year climate extreme by stratum and country Socio-Economic Strata Non- Urban Rural Urban Rural Agricultural Agricultural Labor Labor Transfer Diverse Diverse Bangladesh 32.1 37.8 30.7 11.1 0.8 29.5 17.2 Brazil 0.1 4.1 5.5 6.2 1.0 9.6 7.0 Chile 7.7 13.8 12.7 9.5 14.7 12.6 14.9 Colombia 0.1 0.4 1.0 1.0 0.6 0.6 0.5 Indonesia 29.5 12.1 19.2 23.9 5.9 17.9 19.0 Mexico 52.2 36.7 95.4 52.1 61.8 37.4 43.2 Mozambique 4.3 15.3 16.2 12.4 7.2 26.6 16.0 Malawi 15.8 9.0 110.5 91.0 11.1 30.8 23.0 Peru 2.4 1.9 3.6 2.6 0.5 1.5 1.4 Philippines -17.7 10.2 32.3 25.9 8.5 6.0 3.8 Thailand 4.9 5.8 7.1 5.8 6.4 5.6 5.8 Tanzania 7.2 11.0 14.9 5.3 6.6 21.3 11.9 Uganda -0.1 1.6 16.4 2.9 0.1 1.0 0.6 Venezuela 4.0 5.1 12.1 10.1 0.0 7.2 6.6 Vietnam 5.1 7.0 0.0 0.0 3.9 6.3 6.4 Zambia 0.0 17.7 102.0 32.5 10.9 41.1 10.6 Average 9.2 11.8 30.0 18.3 8.8 16.0 11.7 Source: Authors’ simulations 11 Ahmed et al. (2009)
- 13. Sensitivity of Tanzanian Poverty to Climate Volatility • Ahmed et al. (2011, GEC) • Statistical analysis – Historical grains yields explained by climate variables – Predictions using data from 22 global climate models • Interannual yield changes proxy interannual productivity changes under 1971-2001 & 2002-2031 climate – variation in interannual production D = variation in interannual yield D & variation in interannual D in area harvest = 0 • Simulations are perturbations from 2001 benchmark – Comparability across runs => sensitivity analysis 12
- 14. Sensitivity of Poverty in Tanzania to Climate Outcomes: Distribution of % Point Changes in National Poverty Rate Impact of most extreme harmful climate on poverty Impact of most extreme beneficial climate on poverty Outcomes within box represent 75% of all predicted outcomes 13 Ahmed et al (2011)
- 15. Take Homes • Agriculture a key linkage between climate volatility & poverty vulnerability • Income and price effects determine who is affected • Comparative static CGE tool for sensitivity to climate • Future impacts are likely to be complex across countries, with great uncertainty in climate predictions – Lessons to be learned from historical volatility 14