Future urban ecological land transition and its implications for high-heat exposure in China

Urban ecological land (UEL) is an important nature-based solution for mitigating human exposure to extreme heat (i.e., high-heat exposure, HHE), but the impacts of future UEL transition remain unclear. This study developed a high spatial-temporal resolution dataset (30 m) of urban land cover in China during the 21st century under the shared socioeconomic pathway and the representative concentration pathway (SSP-RCP) to quantify the contribution of UEL transition to HHE. Results showed that UEL transitions will influence 0.12–0.26 °C of the HHE from 2021 to 2100 and is the dominant driver in 10.2%–22.8% of cities (including 95.1 million to 181.2 million people in 2100), with substantial regional disparities. Moreover, UEL landscape pattern is a more important factor than area. Specifically, the UEL evolution pattern will dominate the exposure of 8.02 to 10.77 million people to extreme heat within the urban cores (i.e., predominant urban areas) in the SSP1-2.6 and SSP2-4.5 scenarios, especially in the eastern cities. Under the SSP3-7.0 and SSP5-8.5 scenarios, the UEL evolution pattern will dominate the exposure of 2.44 to 5.34 million people to extreme heat on the expansion surfaces (i.e., areas transitioning from rural to urban), especially in the western cities. The optimization of UEL landscape patterns should be a top priority as an urban heat adaptation strategy to maximize urban resilience to climate change.