Population concentration in high-complexity regions within city during the heat wave.

This article investigates the impact of the 2018 summer heat wave on urban mobility in Seoul and examines how economic complexity influences the resilience of small business clusters within the city. Using subway boarding/alighting data and mobile phone mobility data, the study finds that extreme heat generally reduces the floating population, but areas with higher economic complexity—measured by the Economic Complexity Index (ECI), which reflects the diversity, ubiquity, and sophistication of economic activities—experience smaller declines in population flow. The results suggest that economically complex urban regions attract and sustain more visitors during heat waves, thereby exhibiting greater thermal resilience and supporting urban vitality. The study also notes that diversity of businesses alone does not mitigate heat-related mobility declines, and that these findings hold across different demographic groups, with some variation by age. This research highlights the role of economic complexity as a key factor in spatial disparities of urban resilience to climate-induced stressors and underscores the importance of considering intra-city economic structures in climate adaptation planning.