Unveiling the building embodied carbon dynamics in Yangtze River Delta: Spatial and life cycle perspectives

Understanding and reducing the greenhouse gas emissions from building sector is significant to realize the net zero society. This research presents a bottom-up approach leveraging nighttime light (NTL) data to quantitatively assess and spatially represent urban building Material Stock (MS) and Embodied Carbon Emissions (ECE) throughout the "cradle-to-gate" lifecycle, at the micro-unit level, within the rapidly urbanizing Yangtze River Delta (YRD) region. Our primary focus is on investigating the dynamics and evaluating the impacts of building material stocks and the associated embodied carbon under urban expansion. Key findings include: (1) From 2000 to 2020, the YRD experienced a significant increase in building MS, with development expanding more rapidly along the southeast-northwest axis than the southwest-northeast axis. (2) Building ECE grew markedly in the YRD, especially in coastal areas, shifting from a concentrated singlecenter pattern to a multi-center one. The growth trends of building ECE among these cities varied widely, ranging from 0.64 to 85.71 Tg per year (Tg/a). (3) Construction materials such as sand, gravel, cement, and brick dominated the MS in both residential and non-residential buildings. Cement, steel, brick, and aluminum were the main contributors to building ECE. Notably, despite their lower volumes, copper and aluminum had substantial environmental impacts due to their high ECE contributions. (4) By categorizing cities into four types based on ECE per capita and growth trends, we identified varied urban development and environmental impacts across the YRD.