Urban Tree CO2 Compensation by Albedo

Urban form and surface properties significantly influence city liveability. Material choices in urban infrastructure affect heat absorption and reflectivity, contributing to the urban heat island (UHI) effect and residents’ thermal comfort. Among UHI mitigation strategies, urban parks play a key role by modifying the microclimate through albedo and evapotranspiration. Their effectiveness depends on their composition, such as tree cover, herbaceous layers, and paved surfaces. The selection of tree species affects the radiation dynamics via foliage color, leaf persistence, and plant morphology. Despite their ecological potential, park designs often prioritize aesthetics and cost over environmental performance. This study proposes a novel approach using CO2 compensation as a decision-making criterion for surface allocation. By applying the radiative forcing concept, surface albedo variations were converted into CO2-equivalent emissions to allow for a cross-comparison with different ecosystem services. This method, applied to four parks in two Italian cities, employed reference data, drone surveys, and satellite imagery processed through the Greenpix software v1.0.6. The results showed that adjusting the surface albedo can significantly reduce CO2 emissions. While dark-foliage trees may underperform compared to certain paved surfaces, light-foliage trees and lawns increase the reflectivity. Including evapotranspiration, the CO2 compensation benefits rose by over fifty times, supporting the expansion of vegetated surfaces in urban parks for climate resilience.