Impacts of urban landscape pattern changes on land surface temperature in Southeast Brazil

Abstract

Urban sprawl is a global concern, considering the current climate change scenario. The conversion of natural habitats or other land uses to urban areas increases the Land Surface Temperature (LST), impacting people mainly in tropical regions, such as Brazil, where the temperature is aggravated by high air humidity. In this context, we assessed the seasonal variation of LST in response to the land-use/land-cover (LULC) changes over a large city in southwest Brazil during the last 36 years (1985–2020). We used Mapbiomas LULC data and LST retrieved from the Landsat series with the Google Earth Engine platform. The methodology involved the change detection analysis from 1985 to 2020 for all LULC types, a non-parametric Dwass-Steel-Critchlow-Fligner test to estimate the LST spatio-temporal variability over different LULC types, and a non-parametric Sperman's rho test and scatter plots to relate LST changes to the LULC patterns. The results presented areas exchanging under an intense urbanization process, wherein nearly 13% of the transitions were from agricultural to urban areas. These transitions occurred jointly with an increase in temperature for all LULC types. Forest formation registered the lowest LST and a moderate to strong negative correlation with LST in both seasons. On the other hand, urban areas showed the highest temperatures and a moderate to strong positive correlation with LST in summer. From 1985 to 2020, the mean temperature in urban (built-up) areas during the summer increased by 7 °C. In 2020, the mean temperature in urban areas was 32.5 °C and 27.8 °C in forested areas during the summer. The main contribution of this study is to provide evidence-based support for establishing LULC governance at the city scale. It offers essential scientific information about the detrimental impact of urban sprawl against the climate benefits of green infrastructure on the city scale, even in tropical regions with high forest fragmentation, temperatures, and long periods with high air humidity.