Evaluating contributions of urbanization and global climate change to urban land surface temperature change: A case study in Lagos, Nigeria

Abstract This study aims to develop a general method and evaluate the contributions of localized urbanization and global climate change to long-term urban land surface temperature (ULST) change. Combined daytime and nighttime daily MODIS products were used to fill data biases from satellite-observed data and applied to tropical regions during dry season from 2003 to 2021. Lagos, a fast-growing metropolis in West Africa, is selected as an example for reference. The results are summarized as follows. 1) Long-term annual ULST is confirmed to be controlled by urbanization, global climate change, and interannual climate variation. 2) Linear regression is used to remove the interannual climate fluctuations on long-term observed LST time series. 3) Urban-rural comparison method has been developed to separate the contributions of urbanization and global climate change to long-term ULST changes. Both urbanization and global climate change are verified to contribute to the ULST increase with positive trends. 4) Daytime ULST increased the most in the afternoon time at a mean rate of 1.429ºC per decade, with 0.985 ºC (10yr)-1 contributed by urbanization and 0.444 ºC (10yr)-1 contributed by global climate change. Nighttime ULST increased the most after midnight at a rate of 0.563ºC (10yr) -1, with 0.56 ºC (10yr) -1 contributed by urbanization and 0.003 ºC (10yr) -1 contributed by global climate change. 5) Urbanization is generally to be responsible for around 60.97% of the urban warming. The increasing urban-induced hot has been causing urban residents to suffer more heat-based health risks and increasing the extreme events. Therefore, the results are of useful reference for both urbanization and climate change related issues in the geo-science field.