An Assessment of Long-Term Urban Heat Island Impact on Istanbul’s Climate

Abstract

Istanbul with its high urban population increase and rapid rate of its unplanned urbanization, it is critical to investigate the relations between urban heat island, population growth, and changes in the urban land use. The aim of this work is to study the local climate change and the effects of urbanization on urban climate of megacity Istanbul. Temporal variations of urban heat island (UHI) and UHI intensity in Istanbul were analyzed by using air temperature data measured by five meteorology stations for the period of 1951–2020. Minimum, maximum, and mean temperature data of Istanbul were used to understand the possible impacts of urbanization on the climate of the megacity. In addition, Corine Land Cover (CLC) datasets for the years 1990, 2000, 2012, and 2018, were used to visualize the spread of urban cover throughout the city. Seasonal observations data were statistically tested for monotonic trends. Significant upward trends in temperature were found in all selected stations, both rural and urban. The air temperature in urban areas, densely populated residential areas of the Istanbul, has increased more in years compared to its rural parts. The results showed an increase of night time (minimum temperature) temperature in both urban and rural stations between 0.010 – 0.047 °C yr-1 and an increase of daytime (maximum temperature) in all stations between 0.026 – 0.034 °C yr-1. The urban heat island impact increased over Istanbul with the expansion of the urban areas toward rural areas further reducing green areas.