Projection of the future outlook of temperature and precipitation in Urmia Lake basin by the CMIP6 models

In this research, the climatic variables of temperature and precipitation of Urmia Lake catchment area were evaluated and projected using CMIP6 models under two scenarios SSP1-2.6 and SSP5-8.5 in the future periods (2031-2055 and 2071-2095). First, the accuracy of the models for the base period (1990-2014) was evaluated using Taylor diagram and RMSE and NRMSE indices after downscaling with different methods of quantile mapping, and among the models, the MRI-ESM2-0 for temperature and INM-CM5-0 for precipitation using the SSPLIN downscaling method were selected to project the future climate, then the future temperature and precipitation data were produced. The results of comparing the temperature and precipitation of the future periods with the base period showed that the average annual temperature of the basin will increase under all scenarios. The average annual temperature increase of the basin in the near future in the optimistic and pessimistic scenarios will be 1.5 and 1.8 degrees Celsius, respectively, and in the far future, 1.4 and 4 degrees Celsius respectively. The average annual precipitation will decrease in all scenarios, in the near future it will decrease by 19.9 and 21.6 percent in the optimistic and pessimistic scenarios, respectively, and by 12 and 28.6 percent in the far future, respectively. Based on the spatial distribution of changes in temperature and precipitation in the future periods, the greatest increase in temperature and the greatest decrease in precipitation will occur in the northern areas of the basin.