Regional warming from urbanization is disproportionate to urban expansion rate

Abstract

Rapid urban expansion is known to induce regional warming that can exacerbate extreme heat risks. Although urban temperature changes are closely linked to vegetation reduction and urban growth rate, the warming sensitivity to urbanization across different climatic regimes under normal versus extreme heat conditions remains unclear. Here we use high-resolution near-surface air temperature data (1985–2018) and a global climate model to quantify regional warming sensitivities to urbanization during the warm season. Our results show that urbanizing areas in Europe and North America characterized by wetter climates and abundant rural forests manifest larger urban-rural contrasts in evaporative capacity, resulting in warming sensitivities that are two to three times greater than those in East and South Asia. Under extreme heat conditions, those sensitivities amplify. Thus, despite slower urban expansion, Europe and North America experience more pronounced warming (up to 1.48°C) compared with East and South Asia, where urban growth is twice as extensive. These findings underscore the warming risks in moist climates.