Projections of temperature and precipitation trends using CMhyd under CMIP6 scenarios: A case study of Iraq's Middle and West

Climate change is becoming a leading issue in the 21st century due to its devastating environmental and socioeconomic impacts. It is believed to have significant impacts on the water resources and groundwater in the Middle East region, especially in Iraq. In this study, three different global climate models, under the 6th IPCC report, were downscaled under two SSPs scenarios in the middle and west of Iraq. The downscaled models were fixed for bias using CMhyd (climate model data for hydrologic modeling) over the study area. This was achieved using data from four locally chosen weather stations from 1983 to 2022. Three CMIP6 global models were considered and compared. These were the Australian Community Climate and Earth-System Simulator version 1 (ACCESS-CM2), the Beijing Climate Center Climate System Model version 2 (BCC-CSM2-MR), and the sixth version of the Model for Interdisciplinary Research on Climate (MIROC6).The findings of this study show that the temperature and precipitation changes in the three models under two scenarios in the future period (2023-2050) show an increasing trend compared to the observation period (1983-2014). The results of the generated predictions show that there will be an increase in annual maximum temperatures by this century's end, by 1.26-2.08 degrees C under scenario SSP2-4.5 and 1.57-2.34 degrees C under scenario SSP5-8.5 across all study stations. The study found that the annual increase in precipitation over the observed period varies between scenarios (SSP2-4.5 and SSP5-8.5), ranging from +3.56 to +3.87% for SSP2-4.5 and + 7.22% to +12.61% for SSP5-8.5. The results should help improve our understanding of the effects of climate change on the study region and encourage planners and stakeholders to identify optimal strategies for mitigating them.