Urban Agglomeration and Temperature: A Case Study of Tokyo

Abstract In urban areas, temperatures tend to rise, a phenomenon known as the urban heat island effect. This study uses panel data on climate and urban structure to examine how urban agglomeration—specifically, building height and building coverage ratio—affects urban temperatures. A key feature of our analysis is the use of air temperature data, including maximum, minimum, and mean temperatures, as well as the diurnal temperature range—the difference between maximum and minimum temperatures. Focusing on Tokyo's 23 wards, we use 1-km mesh temperature data for August and September from 2016 and 2021 to examine summer urban temperature dynamics. Our baseline results indicate that (1) greater building height increases minimum and mean temperatures, (2) greater building height reduces the diurnal temperature range, and (3) higher building coverage ratio lowers minimum and mean temperatures. These findings suggest that urban agglomeration affects urban temperatures. Without appropriate urban development policies, urban summer temperatures are likely to continue to rise.