Quantifying projected changes in evaporation and solar irradiation for Iraq in the 21st century using representative concentration pathways

Abstract Iraq's dry and semi-arid climate makes it highly vulnerable to climate change impacts including increased solar irradiation, evaporation rates, and water scarcity risks. This study utilizes the CMIP5 climate model projections from CCSM4 under RCP2.6 and RCP8.5 scenarios to analyze the projected changes in annual evaporation and solar irradiation across Iraq over 2020–2100. The analysis is conducted spatially across 18 locations and temporally across four future periods (2020–2040, 2041–2060, 2061–2080, 2081–2100). Under RCP2.6, evaporation rates are estimated to increase by 11–16.3 kg/m2 (+11% to +20%) in northern Iraq and 16.3–20.1 kg/m2 (+16% to +25%) in southern Iraq by 2100. Solar irradiation is projected to rise marginally by 1.8–3.4 W/m2 (+1% to +2%) countrywide, with the highest levels in western Iraq (224.4–252.3 W/m2) and lowest in northern areas (223.5–232.7 W/m2). The projected rising evaporation can significantly exacerbate water scarcity risks, while the limited irradiation increase can impact long-term planning of solar energy investments. The quantified projections highlight risks to Iraq's water and energy security, underscoring the urgent need for adaptation strategies to enhance resilience.