Integrated Assessment of Climate Change Impacts and Adaptation in Agriculture: The Case Study of the Wami River Sub-basin, Tanzania

Abstract

This study evaluates the impacts of climate change and an adaptation strategy on agriculture in the Wami River sub-basin in Tanzania. This study uses the Agricultural Model Improvement and Inter-comparison Project (AgMIP) framework that integrates climate, crops and economic models and data using a novel multi-model approach for impact assessment of agricultural systems under current and future conditions. This study uses five Global Circulation Models (GCMs) from the fifth phase of the Coupled Model Inter-comparison Project (CMIP5), two crop simulation models, and one economic impact assessment model. In this study, a representative agricultural pathways (RAP) that characterises future conditions following ‘business-as-usual’ trends was developed and used to model future agricultural systems in the Wami River sub-basin. Results show that by mid-century, the maximum and minimum temperatures will increase by 1.8–4.1 °C and 1.4–4.6 °C, respectively. Rainfall is predicted to be variable with some places projected to increase by 12%, while in other areas it is projected to decrease by 14–28%. Maize yields under these conditions are projected to decrease by 5.3–40.7%. Results show that under current conditions, 50–60% of farm households are vulnerable to losses due to climate change. The impacts of climate change on poverty and per capita income are also projected to be negative. Under the current production system, poverty rates were projected to increase by 0.8–15.3% and per-capita income to drop by 1.3–7.5%. Future socio-economic conditions and prices offset the negative impacts of climate change. Under future conditions, the proportion of households vulnerable to loss is estimated to range from 25 to 50%. Per-capita income and poverty rates are expected to improve under the future climate change conditions. Poverty rates would decrease between 1.9 and 11.2% and income per-capita would increase between 2.6 and 18.5%. The proposed future adaptation package will further improve household livelihoods. This integrated assessment of climate change projections using the improved methods and tools developed by AgMIP has contributed to a better understanding of climate change and adaptation impacts in a holistic manner.