Abstract: The research on urban carbon emissions based on the full life cycle assessment is an important basis for formulating collaborative urban emission reduction strategies. Although there are increasingly fruitful research results, the spatial scales, industrial areas, and research methods of different studies differed greatly. We reviewed literature in both Chinese and English between 1998 and 2024, summarized the research trends and disciplinary differentiation characteristics of multiscale urban carbon emissions from a life cycle perspective, and then compared the key factors and mechanisms of the life cycle of carbon emissions at the three scales of city, block, and building based on the method of knowledge graph analysis. As the research scale shifted from macro (cities) to micro level (buildings), the methods transitioned from input-output model-based analysis to life cycle-based analysis, and the factors affecting the life cycle of carbon emissions shifted from socio-economic and urban form characteristics to buil-ding functional forms, building materials, and structures. Finally, we explored urban collaborative carbon reduction strategies from three aspects: building a multiscale carbon emission life cycle data management platform, analyzing the dynamic evolution mechanism of the life cycle of urban carbon emissions, and achieving cross-regional and multi-sectoral carbon reduction collaborative management. These strategies would provide reference for low-carbon oriented urban sustainable development and the achievement of dual carbon goals.

Key words: life cycle, multiscale, carbon emission, collaborative emission reduction