Evaluation of General Circulation Models CMIP6 Performance and Future Climate Change over the Omo River Basin, Ethiopia

Abstract

One of the world’s major issues is climate change, which has a significant impact on ecosystems, human beings, agricultural productivity, water resources, and environmental management. The General Circulation Models (GCMs), specially the recently released (coupled model intercomparison project six) CMIP6 are very indispensable to understand and support decision makers to identify adaptation strategies in response to future climate change in a basin. However, proper selection of skillful GCMs and future climate assessment is a prior task to climate impact studies. The objective of the study is an attempt to appraise the climate model’s performance and future climate scenarios of Shared Socioeconomic Pathways (SSPs) in the Omo River Basin. The performance evaluation of 20 GCMs of the CMIP6 was properly performed to reproduce the precipitation and the maximum temperature in the basin. Their performance has been carried out against the best selected mean monthly Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) precipitation and European Community Medium Water Range Weather Forecasts Version 5 (ECMWF-ERA5) maximum temperature. The GCMs of the CMIP6 were selected and ranked using the compromise programming method of multi-criteria decision making. The result shows that ensemble models and NorESM2-MM models have been designated to reproduce the precipitation and maximum temperature in the basin respectively. The Mann–Kendall trend test was executed to appraise the trend of selected CMIP6 models, and subsequently, downscaling and bias correction techniques were conducted. The projected seasonal precipitation of June, July, August, September (JJAS) and March, April, May (MAM) shows an increasing trend with 10.86, 17.66, 38.96 and 11.85, 22.1, and 40.7% under SSP2452031-2060, SSP5852031-2060, and SSP5852071-2100 scenarios respectively. Furthermore, increasing trends were detected in MAM by 12.8% and decreasing trends in JJAS were detected by 15.23% under SSP2452071-2100 scenario. The maximum temperature projection will be increased on average by 0.95, 1.78, 1.4, and 3.88 °C in JJAS and 1.53, 2.24, 1.56, and 3.89 °C in MAM under climate change scenarios of near-future SSP2452031-2060, SSP5852031-2060, far-future SSP2452071-2100, and SSP5852071-2100, respectively. Additionally, the basin has shown temporal-spatial climate fluctuation in terms of precipitation and maximum temperature.

Unveiling Deviations from IPCC Temperature Projections through Bayesian Downscaling and Assessment of CMIP6 General Circulation Models in a Climate-Vulnerable Region

“…In relation to the goodness-of-fit (GOF) metrics employed, it is noteworthy that both the low variability in the correlation coefficient values and the relative inconsistency shown in the rankings obtained for each measure were detected in several previous studies worldwide [53,61,110,111].…”

“…Thus, the evaluation of GCMs at a local scale is absolutely necessary before incorporating them into a Multi-Model Ensemble (MME), aiming to identify possible deviations or abnormal discrepancies in certain GCMs that may undermine the predictive capacity of studies. This locally based evaluation approach, combined with MME, is prevalent in numerous research endeavors [32,35,[52][53][54][55][56]. Nevertheless, a notable absence of such a localized assessment for the European Mediterranean region has been identified [57], with few studies conducting a comprehensive comparison of model-performance disparities [58][59][60][61].…”

Assessment of precipitation and near-surface temperature simulation by CMIP6 models in South America

“…Several studies have evaluated the performance of CMIP6-GCMs in different regions of the globe, such as North America [1,6,7], Central America [7,8], Africa [9][10][11][12], Asia [13][14][15][16][17], Europe [18,19], and Oceania [20]. For South America (SA), such analyses are even more problematic and necessary, given that the continent has climate complexity resulting from its great latitudinal extension and topographic heterogeneity [21,22].…”

Spatiotemporal changes in future precipitation of Afghanistan for shared socioeconomic pathways

“…The SSP1-1.9 represents a mitigation approach designed to limit global warming to below 1.9 °C by the conclusion of the 21st century. On the other hand, the SSP1-2.6 is a trajectory with low emissions that has been formulated to limit the increase in global temperature to below 2.6 °C [ 48 ]. The significance of these situations has escalated due to the recognition by governments and researchers of the urgent necessity to augment climate action and pursue more ambitious reductions in greenhouse gas emissions to avert the most severe repercussions of climate change.…”