Note unexpected reverse in city-level CO2 carbon peak status: Challenges to China's ambitious climate goals

As the world's leading carbon emitter, China has committed to ambitious “Dual Carbon” targets for 2030 and 2060. Given the variation in cities' socioeconomical status and mitigation potential, identifying city-specific emission trajectories and strategies is crucial to achieving the national climate goals. In this paper, we developed an updated time-series (yearly from 2005 to 2023), bottom-up (using source-level emission profile), full-scale (including fossil fuel combustion sectors, and industrial processes and indirect emissions sectors) CO₂ emission inventory covering all Chinese cities (including 339 prefecture-level cities), by using a hybrid method covering big data analysis, remote sensing applications, and GIS technology. It showed that overall CO₂ emissions in Chinese cities grew steadily from an average of 20.64 million tons in 2005 (95 % CI 0.25–88.68 million tons) to 37.80 million tons in 2020 (95 % CI 1.39–164.36 million tons), driven mainly by emissions from industrial and indirect sectors (increase by 12.45 and 21.63 million tons). We also identified an unexpected reversal in emission status from 2020 to 2023, with 65 cities shifting back from previously decline or plateau status to growth status, reversing earlier progress. Meeting China's 2030 peak emissions target will require stricter emission reduction scenarios, with significant reductions in emissions from the industrial and power sectors, as well as indirect emissions (collectively accounting for 1739 million tons of reductions between 2023 and 2035), aiming to achieve at least the 60th percentile of the corresponding benchmark. Our paper advocates for the implementation of a real-time carbon emission monitoring system at the local government level and suggests that high-emission cities could achieve noticeable reductions in emissions by adopting benchmark emission performance standards from their peer cities, while simultaneously exploring low-carbon development pathways. To enhance practical relevance, we further propose actionable recommendations targeting key implementation challenges, including funding, technology, and institutional frameworks for effective urban decarbonization.