Cooling potential of global urban roof greening

Abstract

Increasingly frequent and extreme heat is posing significant threats to urbanites. Green roofs have emerged as a promising nature-based solution to mitigate urban heat, but their cooling potential at a global scale remains unquantified. Here, using ultra-high-resolution building footprint data, we simulated and assessed the cooling potential of roof greening for global cities. Our estimates indicate that roof greening has the potential to reduce land surface temperatures (LST) across global cities by 0.57–1.58 °C during the day and 0.14–0.39 °C at night, depending on the extent of roof greening. Asia showed the greatest cooling benefit to urban population despite not having the highest cooling potential. Moreover, green roofs provided additional benefits by reducing the diurnal temperature range by 0.39–1.10 °C due to higher cooling potential during the day than at night. These results highlight the substantial cooling potential of roof greening on a global scale, providing a scientific basis to inform urban climate mitigation policies.