The purpose of this research is a comprehensive evaluation of climate change effects on three parameters of temperature, precipitation and potential evapotranspiration over the country of Iran in next time periods of 2010-2039, 2040-2069 and 2070-2099, and under scenarios A2 and B2. After preparation of measured temperature and precipitation data and calculation of potential evapotranspiration for the base time period of 1960- 1990 in 46 meteorological stations (with a nationwide distribution), it was tried to have initial zoning of these three parameters over the country. After receiving of maximum and minimum temperature and the values of precipitation from HadCM3 model under scenarios A2 and B2 for the mentioned next three time periods, these data were downscaled. Then by preparation of the related maps for the mentioned three parameters in the mentioned next time periods, spatial and temporal variations of these climatic parameters under A2 and B2 scenarios were extracted and interpreted. Results show that the highest increase in temperature occurs in west parts of the country, but the highest increase of potential evapotranspiration belongs to central regions of Iran. However, precipitation varies temporally and spatially in different parts of the country depending on the used scenarios and the selected time periods.

Keywords