Analysis of projected climate change in sorghum growing semi-arid rift valley of Ethiopia

Abstract

Global warming projected to have a significant impact on agricultural water availability for crops in Africa in particularly in Ethiopia. Therefore, the study was conducted to analyze the projected change of temperature and rainfall in sorghum growing semi-arid rift valley of Ethiopia. The weather data for 11 stations were generated using AgiMP5 technique for RCP 4.5 and 8.5 and for the period of 2050s and 2080s. MAKESENS employed for the detection of trend of extreme indices.  InStat v3.37 were used for the analysis of start, end, and length of growth season. Under RCP 4.5, the projected mean annual minimum air temperatures in CRV, ERVE and NRVE could increase respectively by 1.9 °C (2050s) and 2.6 °C (2080s), 1.8 °C (2050s) and 2.5 °C (2080s) and 1.88 °C (2050s) and 2.69 °C (2080s). Under RCP 8.5, however, with same location it will projected to increase in both time frames (2050s and 2080s) in all studied sites. The mean annual maximum air temperature, projected under RCP 4.5 in the CRV, ERV and NRVE will increase by 1.59 °C (2050s) and 2.18°C (2080s),1.42 °C (2050s) and 2.08 °C (2080s) and 1.46 °C (2050s) and 2.09 °C (2080s) respectively. However, under the RCP 8.5, at same regions it projected to rise in both periods (2050s and 2080s). This will be convoy with increase of the hot and cold extremes’ indices in regions. The mean percentage change of annual rainfall is projected to  decrease insignificantly in (0.6-5.5% and 2.6%) and increase (0.85-12.3% and 22.3%)  in half of the stations located in CRV and ERVE, whereas, in NRVE it will projected to increase (6.1-14.6%) under RCP 4.5 in all stations in 2050s. Though the annual projected rainfall under RCP 4.5 in 2080s will decline in range of 2.1-10.1%, 3.12-4.5% and 0.9-4.6% at CRV, ERVE and NRVE respectively. In most of the location in CRV and ERVE stations growing season rainfall will projected to decline from 1.45% to 53.8% and 0.8 to 8.8%, whereas, in NRVE it will projected to increase in 9.2 to 19% under RCP 4.5 in period of 2050. The projected SOS will be changed in mixed pattern, whereas and LGP will prolonged in most locations. The findings indicated that there has been a change of projected climate change in semi-arid RV, which will be alter the agricultural practices in depletion of soil moisture. Therefore, in adjusting planting timing and using early/medium maturation sorghum varieties, may be necessary for farmers in the region. Soil and water management needs attention.