Abstract:
In countries like Ethiopia where vulnerability is high and adaptive capacity is low, studying impacts of climate change and analysis of future adaptation measures at local scale is critical. In this view, this study was conducted in Arsi Robe, Asasa, Debre Zeit and Kulumsa areas of central highlands of Ethiopia to characterize the local climate, model climate change impacts and adaptation options for the changing climate by 2050s under RCP4.5 and RCP8.5 scenarios. Historical climate data (1981-2015), future climate data downscaled using the ensemble of seventeen climate models, crop and soil data were analyzed. Past and future climate characterization was assessed through seasonal and annual rainfall variability, onset and cessation of rainy season, length of growing season, dry spell length and analysis of extreme climate indices using INSTAT+ v3.37 and RClimDex software. Start of the rainy season was highly variable than its cessation in the study area. In this regard, Asasa has experienced high variability of the onset date (CV=37%) followed by Kulumsa (CV=32.6%) and Debre Zeit (CV=32.4%). Moreover, the seasonal rainfall analysis of future climate revealed that, high increment of Kiremt and Belg rainfall will be expected in all study sites under both RCPs. The mean average temperatures showed an increasing trend at inter annual scale of 1.9 and 2.2 ºC at Arsi Robe, 1.9 and 2.1 ºC at Asasa, 1.7 and 1.9 ºC at Debre Zeit and 1.8 and 2.1 ºC at Kulumsa under RCP4.5 and RCP8.5, respectively. Besides, the projection of extreme temperature indices showed that, warm extremes are increasing while cold extremes decreasing in all study sites, this series clearly indicate significant warming. The crop model simulation indicated a negative impact on yield in all study sites under both RCPs. There will be high yield reduction under RCP4.5 than under RCP8.5 at Arsi Robe and Asasa while the reverse is true at Debre Zeit and Kulumsa sites for Dandaa and Kakaba cultivars. Kakaba showed high yield potential than Dandaa in all study sites, and best adaptation measures suggested were late plating, 30 cm row spacing and 100 kg/ha N with split applications at planting and tillering for Asasa and Kulumsa, while combinations of late planting, 30 cm row spacing and 100 kg/ha N with split applications at planting, tillering and heading were suggested for Debre Zeit and Kulumsa areas. Therefore, growing both cultivars under future climate condition with the above improved management practices could ensure high yields during a good rainy season
