Evaluation and Projection of CMIP6 Simulations of Climate Variables in the Rift Valley Lakes Basin, Ethiopia

Abstract

<title>Abstract</title> The objective of this study is to evaluate the performance of twenty-eight bias-corrected GCMs and project changes in climate variables using CMIP6 from the reference period (1985–2014), and the two future periods (2035–2064 and 2065–2094) under three Shared Socioeconomic Pathways (SSP2-4.5, SSP3-7.0 and SSP5-8.5). Comprehensive rating metric (CRM) based on seven statistical metrics was used to evaluate the performance of GCMs. The multi-model mean ensemble (MMME) of four carefully selected best performing CMIP6-GCMs for each climate variables were used for projection. Considering respective MMMEs, the projected mean precipitation, maximum temperature (Tmax), minimum temperature (Tmin), and relative humidity (hurs), will increase, but solar radiation (rsds) will decline, under all SSPs in both periods as response to global warming. The projected precipitation increase may augment water availability in the Rift valley Lakes Basin (RVLB). However, more intense and frequent heavy precipitation with short-duration may lead to flash floods and landslides to damage crops and infrastructures. In addition, raise on Tmax, Tmin and windspeed may lead to high evapotranspiration demand, recurrent drought, and water insecurity. To properly comprehend and respond appropriately, more research is needed to determine how these changes in climate variables affect sustainable water resources management and water security in RVLB.