Prediction of future climate variability and its implications for rainfed agriculture in the Guder watershed, Ethiopia

Abstract

This study aims to predict the future changes in mean monthly temperature and rainfall over the Guder watershed during the early (2011-2039), middle (2041-2069), and end (2071-2099) of the century under the Representative Concentration Pathways (RCPs) scenarios. A statistical downscaling procedure was used to downscale the results of the CanESM2 model. Observed temperature and rainfall data were used to downscale the future climate from ensembles of 20 GCMs of the CMIP5-CanESM2 model for three RCP scenarios, namely RCP2.6, RCP4.5 and RCP8.5. The results showed that mean annual and seasonal rainfall will increase throughout the watershed with high variability across both the RCPs and the study periods. Regardless of the projection period, the minimum temperature is expected to increase by 0.06 °C (RCP2.6), 0.09 °C (RCP4.5) and 0.11 °C (RCP8.5) by 2099. Similarly, the average monthly maximum temperature for 2011-2099 showed persistent warming between 0.96 °C and 1.02 °C under RCP2.6, 0.02 °C and 0.42 °C under RCP4.5, and 0.05 °C and 0.96 °C under RCP8.5 compared to the baseline period. Accordingly, the cumulative impacts of projected rainfall and temperatures in the catchment are expected to be negative. Therefore, policymakers and local planners can use this study to strengthen the preparedness of smallholder farmers' through promoting adaptation strategies such as installing early warning systems (particularly, by making existing early warning system functional), constructing soil and water conservation measures, and raising awareness to diversify their income sources to mitigate possible impacts of extreme events (e.g. heat stress, uncertain torrential rainfall, drought and floods) and build resilient livelihoods. Above all, rural people in the Guder catchment should collaborate with local planners and policymakers in terms of accepting and implementing innovative measures (improved seed & in organic chemicals), actively participating in soil and water conservation activities (e.g., tracing, tree planting, mulching, conservation tillage) and responding to early warning information, and preparing and using organic fertilizer to ensure food security and build resilient livelihood.