Urban Sustainability and Climate Justice: Spatial Mismatch Between Urban Park Accessibility and Heat Exposure Among Older Adults and Children in Hefei, China

Climate warming and demographic change pose interconnected challenges to urban sustainability, particularly for older adults and children who may face limited access to urban parks and elevated summer land surface temperatures. However, existing studies often examine park accessibility and thermal conditions separately, providing limited understanding of the fine-scale spatial mismatches among park accessibility, population distribution, and surface temperature across these two age groups. From a climate justice and urban sustainability perspective, this study develops a three-dimensional spatial screening framework integrating these dimensions, using the main urban area of Hefei, China, as a case study. Based on road-network data, WorldPop gridded population data, and MODIS/Terra MOD11A2 land surface temperature (LST) data for July 2024, park accessibility for older adults and children was assessed using the two-step floating catchment area (2SFCA) method. Bivariate local indicators of spatial association (Bi-LISA) were employed to identify local accessibility–population associations, which were subsequently overlaid with high-LST hotspots to delineate dual-vulnerability zones. The results indicate that: (1) pronounced inequality exists in modeled park accessibility, with population-weighted Gini coefficients based on normalized accessibility scores of 0.988 for children and 0.875 for older adults; (2) LH-type clusters, characterized by low accessibility at focal grid cells associated with high population density in neighboring cells, are concentrated in the old city core for both groups; and (3) dual-vulnerability zones account for 7.5% of the study area’s mapped area for older adults and 6.6% for children. These percentages represent area-based shares rather than population-based heat-exposure rates. Shared-risk areas are concentrated in the urban core, whereas age-specific risk areas are more fragmented along the periphery. By linking intergenerational equity in green-infrastructure accessibility with the spatial targeting of heat-adaptation interventions, this framework provides empirical evidence to support equitable green-infrastructure provision, age-inclusive climate adaptation, and more inclusive, climate-resilient, and sustainable urban development.