As climate change intensifies and urbanization continues, Fuzhou faces growing public health risks from the urban heat island effect. This study develops a Heat Risk Index (HRI) by integrating the Local Climate Zone (LCZ) classification with the Crichton Risk Triangle framework. Hazard was characterized using quality-controlled Landsat LST and the proportion of valid MYD11A2 composites exceeding a citywide P90 LST threshold. Exposure was represented by normalized population density; ln(P + 1) was used only for cartographic classification. Vulnerability incorporated older population, nighttime light, NDVI, and MNDWI. The continuous HRI was calculated as H × E × V, and ln(HRI) was used only for Jenks five-class map presentation. The results show clear spatial differences among LCZ types and counties, with higher risks concentrated in densely built and populated areas of the five urban districts, Changle, and localized county centers. LCZ differences in LST and HRI were statistically significant (both p < 0.001), and HRI showed significant positive spatial autocorrelation. These findings provide a basis for LCZ-specific heat-risk management while acknowledging uncertainty associated with data-year mismatch, spatial resampling, remotely sensed surface temperature, and the absence of independent health-outcome validation.

We evaluated 30 blue and 31 green spaces in Fuzhou using a July land surface temperature (LST) composite from four quality-controlled Landsat 8 scenes acquired during 2020–2022. A cubic temperature–distance procedure produced positive cooling estimates for all blue spaces and 30 green spaces. Modeled carbon-equivalent potential (MCEP) was calculated as an LST-based heat-energy equivalent under reference parameters, and MCEPA as MCEP per hectare. MCEP totaled 507.07 t CO₂. Median MCEP was 5.32 t for blue spaces and 2.42 t for green spaces (p = 0.284). Unadjusted MCEPA was higher in blue spaces (median 1.38 versus 0.90 t CO₂ ha⁻¹; p = 0.035; Cliff’s δ = 0.318), but the contrast was not significant after Holm correction (adjusted p = 0.211) and may partly reflect differences in patch-area distributions. MCEP increased with patch area, with allometric exponents of 0.606 and 0.865 for blue and green spaces, respectively. Because area is an integration dimension in MCEP, these are scale-dependent relationships. Bayesian Gamma models indicated positive area associations, whereas credible intervals for surrounding-ring NDVI and landscape shape index included zero. Spatial allocation reached 220 of 995 communities. The results describe surface cooling and conditional carbon-equivalent potential, not measured electricity savings or avoided emissions.