Deep decarbonization strategy for synergistic reduction of CO2 and air pollutant emissions in metropolises: A case study of Suzhou, China

Cities play a crucial role in economic development and greenhouse gas emissions worldwide owing to their population density and industrial concentration. In this study, Suzhou, a highly developed metropolis in China, was selected to investigate the deep decarbonization strategies toward achieving dual carbon goals. A bottom-up Long-term Energy Alternatives Planning (LEAP-Suzhou) model was established, encompassing seven key economic sectors: electricity generation, industrial manufacturing, transportation, residential living, public service, agricultural production, and waste disposal. This model estimated Suzhou's energy consumption and historical emissions as well as predicted carbon dioxide (CO2) and homologous pollutant emissions under nine scenarios from 2021 to 2050. The results indicated that the growth in Suzhou's energy consumption significantly slowed from 2016 to 2020, with CO2 emissions reaching 248.21 million tons in 2020. Industrial manufacturing and electricity generation were identified as major contributors to emissions. By coupling new industrialization with the implementation of clean (zero-carbon) power alternatives, rather than relying solely on economic growthdriven scenarios as baselines, Suzhou can achieve its carbon peak target before 2030 while simultaneously reducing homologous pollutant emissions. The adoption of deep decarbonization strategies is expected to reduce net CO2 emissions to 29.44 million tons by 2050 and yield an economic benefit equivalent to 2.1 % of the Gross Domestic Product that year. The findings emphasize the critical roles of targeted measures such as technological innovation, cross-sectoral collaboration, and green markets, in facilitating a net zero-carbon transition.