The widening biophysical divide in urban systems: Evidence from a 24-year study in Europe

Urban areas are increasingly shaped by complex interactions between human activity and biophysical processes, yet their internal spatial dynamics remain insufficiently understood at large scales. In particular, a clear gap remains in understanding whether urban cores (UCs) and their surrounding commuting zones (CZs) are evolving along similar or divergent long-term biophysical trajectories, particularly at continental scale and across multiple indicators. In this study we analyzed 690 Functional Urban Areas (FUAs) in Europe and analyzed four biophysical indicators: Enhanced Vegetation Index (EVI), Leaf Area Index (LAI), Land Surface Temperature (LST), and Evapotranspiration (ET). By explicitly comparing trends between UCs and CZs we assess whether a systematic “biophysical divide” is emerging within urban systems. Our findings suggest that vegetation indices (EVI and LAI) are increasing in the majority of FUAs, but the increase spatial extent is larger in CZs, leading to a vegetation gap between urban cores and their peripheries. In contrast, LST exhibits a tendency to increase more rapidly in UCs, particularly in the Mediterranean region, reinforcing the urban heat island effect. ET revealed comparatively stable patterns, with scarce region-specific increases. Random Forest models followed by Shapley analysis identified land cover as the dominant driver of CZ–UC differences, with urban and forest land cover fractions exerting the largest impact across indicators and regions. Overall, our results provide continental-scale evidence of a widening biophysical divide within European urban systems, driven primarily by land cover dynamics and modulated by human management practices. This study highlights the importance of analyzing urban areas as spatially coupled systems and offers a robust empirical basis to guide future planning policies.