A survey of relationship between urbanization and climate change for major cities in Iran

The present study aims to investigate the urbanization characteristic of population growth during five time windows from 1976 to 2016, which can represent the evidence of climate change. For this purpose, seven major urbanized regions of Iran were chosen to study, which have the population greater than one million in 2016. Three main climatic data called as mean annual temperature, upward long-wave radiation (ULR), and precipitation, by monthly scale, were considered averagely to five aforementioned annual time scales from 1976 to 2016 then were extracted spatially with coordination of 1°N × 1°E around each urbanized region. Temporal change of climatic variables within five time windows indicated the average values of + 2.09 °C, + 11.2 W/m2, and − 21 mm for mean annual temperature, ULR, and precipitation in whole study areas. The most increase for mean annual temperature and ULR values were observed in Mashhad and Tehran-Karaj urbanized regions, respectively. In vice versa, the most decrease for mean annual precipitation values was observed in Ahwaz and Shiraz urbanized regions. A parallel increasing trend for temperature and ULR and a parallel declining trend for precipitation were observed adjusted by increasing urban population in all urbanized regions. In addition, the significant and strong relationships (R2 = + 0.814 to + 0.998) between temperature and ULR variations and urban population were observed in each urbanized region indicating as important signals of climate change affected by urbanization in Iran.