Temporal Analysis of CMIP6 Historical and Projection Emission Scenarios

Globally, impacts of climate change observed across the sources of water, agricultural planning, and socio-economic factors. Objectives of the study are to analyze historical climate data, focusing on rainfall and temperature trends over the period 1981–2014 and to project future climate scenarios under SSP2-4.5 and SSP5-8.5 for the periods 2015–2040 (near term), 2041–2070 (mid-term), and 2071–2100 (end term), assessing changes in seasonal and annual rainfall and temperature. This study investigates historical and projected climate trends in Tiyo Woreda, Arsi Zone, Ethiopia, using data sources Copernicus and ECMWF and CMIP6 climate models under SSP2-4.5 and SSP5-8.5 scenarios. Ensembles global climate models selected from the five Coupled Model Intercomparison Project (CMIP6) are considered under SSP2-4.5 and SSP5-8.5 socio-economic pathways. The research conducted using multiple software tools, such as Excel for data entry and manipulation, Python for data processing, visualization, Heatmaps and plotting, and ArcGIS and GeoCLIM for location of study area and spatial analysis. The result demonstrated historical climate rainfall is highest during the Kiremt, moderate during Belg, and lowest during Bega. Projections both SSP2-4.5 and SSP5-8.5 scenarios suggest that rainfall will generally increase in the mid- and long term, though slight reductions are observed in the near term compared to the historical baseline. Seasonal trends of Bega and Belg rainfall show small near-term declines and slight increase respectively but recover and increase in later periods. Kiremt rainfall exhibits modest but consistent increases, with higher values under SSP5-8.5. Annual rainfall follows a similar trajectory, with gradual increases across the projection horizon. Scenario comparison across SSP5-8.5 consistently projects greater increases in rainfall than SSP2-4.5, particularly in the mid- to long-term. In general historical analysis show mixed rainfall trends with increases in Kiremt and decreases in Bega and Belg, while minimum and maximum temperatures exhibit a warming trend across all seasons. CMIP6 projections indicate an overall increase in seasonal rainfall and temperature, with more pronounced warming under SSP5-8.5. Projections SSP2-4.5 and SSP5-8.5 scenarios of maximum temperature show an increment across the periods of near-, mid- and end-term with the magnitude of 0.7°C, 1.6°C, 2.1°C and 0.8°C, 1.9°C, 3.6°C respectively. These results highlight the need for adaptive strategies in agricultural planning and water resource management to mitigate the impacts of climate change in the Tiyo Woreda.