Abstract
Historical records (1901–2021) of Iraq's air temperature and precipitation were studied and compared. A climatic multi-model ensemble and four emission scenarios with representative concentration pathways (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) are used in this research to explain the changes in future climate indicators in Iraq. The results showed a rise and decline in temperatures and precipitation over the past century, with an average of 1.3 °C and 57mm since 1901. A remarkable rise and decline in temperatures and precipitation occurred at 0.36 °C and 4mm per decade over the past thirty years (1990–2020). A greater increase in temperatures occurred in the southern regions than in the northern regions during summer. A temperature increase of 1.5 °C was observed in Basra City and 1.3 °C in Duhok City. The projected temperature over Iraq is higher than historical temperatures in all scenarios, with a rise of about 0.6°C every ten years. Days in June and September with temperatures exceeding 40 ºC have a greater probability of experiencing temperature increases. Iraq is expected to have a decrease in annual precipitation under the high emission scenarios of RCP8.5. The predictions of the medium emission scenarios RCP4.5 and RCP6.0 are noticeably different from the measurements of Iraqi weather stations, especially in 2006. Precipitation decreases from November to May from the historical period in high emission scenarios (RCP8.5) for the foreseeable future. Increased air temperatures and a lack of precipitation have significant effects on the ecosystem because of droughts and frequent dust storms. Therefore, the most important decision that senior management must make is the formulation of policies and procedures for water routing and storage.