Spatiotemporal variations and multi-scenario simulation of urban thermal environments based on complex networks and the PLUS model: A case study in Chengdu central districts

•The components of urban TEN were extracted based on the "source-corridor-network" concept.•The topological characteristics of urban TEN were analyzed based on complex network modeling.•Multi-scenario simulations and analyses of the drivers of UTE were conducted based on the coupled Markov–PLUS model.•The "boundaries to conserve urban cold sources (BCUCS)" were proposed to evaluate their potential role in UTE management. Urbanization and intense human activity have significantly changed the global urban thermal environment (UTE). Spatiotemporal characteristics, driving factors, and future trends should be well understood to effectively quantify the UTE. Using the "patch–corridor–background" concept in landscape ecology, the spatiotemporal variation of the UTE in the central districts of Chengdu City, Sichuan Province, China, from 2013 to 2023 was explored using various analytical techniques and models. The coupled Markov–patch-generating land-use simulation model was employed to simulate the UTE in 2030 under three different scenarios, while analyzing the drivers. The “boundaries to conserve urban cold sources (BCUCS)” were proposed to evaluate their potential role in UTE management. The results indicate that the intensity of urban heat islands has slowed and decreased significantly in some central areas of the city, with medium temperature zones (MTZ) being the most prevalent type of UTE expansion. Urban heat islands were gradually fragmented, whereas the cold islands aggregated. The spatial distribution of the hot network (HN) continued to extend toward the periphery of the city, whereas the cold network (CN) was more uniformly distributed. An additional future MTZ influenced by changes in the normalized difference vegetation index (NDVI) and normalized difference built-up index (NDBI) is expected to occur, primarily in built-up areas along rivers and vegetated regions. Under the low-temperature scenario, MTZ expansion is projected to be the strongest and most extensive, followed by that under the natural development scenario. Under the high-temperature scenario, the UTE is expected to exhibit several changes, and the newly added heat islands are projected to be fragmented. The “BCUCS” can protect urban cold islands from UTE changes, guide the expansion of urban heat islands, and mitigate the fragmentation of heat islands caused by unbalanced development.