Surface Cooling and Modeled Carbon-Equivalent Potential of Urban Blue–Green Spaces in Fuzhou, China

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.