Water resources restrictions along with uneven distribution of water in different parts of Iran, have caused Iran to be highly vulnerable to climate change impacts. During recent years, IPCC has developed GHG emission scenarios which can be used with AOGCMs to predict climatic status for the future. Herein this research, Hadcm3 was used to simulate climatic parameters for three different periods including 2020s, 2050s and 2080s. Lars-WG weather generator was used as a downscaling tool for 3 different scenarios including A2, A1B and B1. The research was conducted in Kan basin. Base period was 1981-2010. The results show an increase between 0.8-1.3 degrees centigrade for near future. Almost mostly show a decrease in precipitation except for an increase in some months of the winter which is predicted for 2080s. seemingly a decrease in runoff is not beyond the expectations as most scenarios predicted decrease in precipitation.