Do urban green spaces cool cities differently across latitudes? Spatial variability and climatic drivers of vegetation-induced cooling

Urbanization transformed global landscapes, intensifying Urban Heat Islands (UHI), further exacerbated by climate change. Sustainable green urban design offers cooling effects through evapotranspiration and shading with varying effectiveness across regions. This study investigates the role of urban vegetation, particularly trees and grassland, in moderating temperatures across nine European cities from 40°N to 53°N, with Temperate to Mediterranean climates. High-resolution Land Surface Temperature (LST) data, downscaled using a Gradient Tree Boosting model, were integrated with the De Martonne Aridity Index and a Contribution Index (CI) to quantify vegetation-driven cooling across a latitudinal gradient. The results show that tree and grassland cooling effects are not spatially uniform: vegetation in cooler, less arid cities provides stronger thermal mitigation. Regression analysis using Random Forest and Generalized Additive Models revealed that vapor pressure deficit (VPD) most strongly influences vegetation cooling, followed by precipitation and solar radiation. Even similar vegetation types demonstrate differing cooling performance depending on local climatic conditions. This study emphasizes the importance of optimizing urban greening strategies to geographic and climate-specific contexts, offering actionable insights for designing climate-responsive green infrastructure to reduce urban heat.