Qi Bing, Hu Cheng, Yu Yan, Pang Yuting, Wu Fangqi, Yang Xinjie, Liu Huili, Zhang Junqing, Xiao Qitao, Liu Cheng, Xiao Wei
Hangzhou Meteorological Bureau, Hangzhou 310051, China; Zhejiang Lin'an Atmospheric Background National Observation and Research Station, Hangzhou 311300, China.
College of Ecology and Environment, Joint Center for sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China; Yale-NUIST Center on Atmospheric Environment, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science & Technology, Nanjing 210044, China.
J Environ Sci (China). 2025 Nov;157:908-923. doi: 10.1016/j.jes.2024.10.027. Epub 2024 Nov 9.
China is the largest emitter of anthropogenic CO globally, with its cities recognized as significant emission hotspots. Consequently, evaluating anthropogenic CO emissions and the carbon neutral capability (CNC) of Chinese cities is critical for climate change mitigation. Despite this importance, no studies to date have assessed recent and future city-scale CNCs using the top-down atmospheric inversion approach, revealing substantial knowledge gaps regarding regional CO budgets. To address these issues, this research focused on Hangzhou, a megacity known for having the highest forest cover among China's provincial capitals, as study region. Year-round atmospheric CO concentration measurements were conducted from December 2020 to November 2021 at two sites: one urban and one suburban. These observations, along with their difference, were utilized to derive city-scale posterior anthropogenic CO emissions and to evaluate recent and future CNCs. Our key findings are as follows: (1) The manufacturing industry, energy industry and oil refineries/transformation industry were identified as the largest contributors to urban-suburban CO difference, accounting for 36.5 %, 21.3 %, and 16.6 %, respectively. Additionally, 82.5 %, 65.2 %, 81.2 % and 86.3 % of total anthropogenic CO enhancements were attributed to emissions within Hangzhou city in winter, spring, summer and autumn, respectively. (2) The posterior annual anthropogenic CO emission for Hangzhou was estimated at 4.65 (±0.72) × 10 kg/a, indicating significant biases among different prior CO emission inventories. The annual biological CO sink, derived from multiple products, was estimated at -0.48 (±0.16) × 10 kg. (3) The calculated CNC for 2021 was 10.3 % ± 3.4 %, highlighting a substantial gap towards achieving full carbon neutrality. Considering potential increases in ecosystem carbon sinks due to forest age and uncertainties from climate change, it was predicted that at least 65.2 %-82.6 % of anthropogenic CO emissions must be reduced to achieve the goal of full carbon neutrality by year of 2060.
中国是全球最大的人为二氧化碳排放国，其城市被视为重要的排放热点地区。因此，评估中国城市的人为二氧化碳排放和碳中和能力对于缓解气候变化至关重要。尽管具有重要意义，但迄今为止尚无研究采用自上而下的大气反演方法评估近期和未来的城市尺度碳中和能力，这揭示了区域二氧化碳收支方面存在重大知识空白。为解决这些问题，本研究聚焦于杭州，这座以中国省会城市中森林覆盖率最高而闻名的特大城市作为研究区域。在2020年12月至2021年11月期间，在两个地点进行了全年大气二氧化碳浓度测量：一个城市站点和一个郊区站点。这些观测数据及其差值被用于推导城市尺度的后验人为二氧化碳排放量，并评估近期和未来的碳中和能力。我们的主要发现如下：（1）制造业、能源行业和炼油/转化行业被确定为城市-郊区二氧化碳差值的最大贡献者，分别占36.5%、21.3%和16.6%。此外，冬季、春季、夏季和秋季人为二氧化碳总增量的82.5%、65.2%、81.2%和86.3%分别归因于杭州市区内的排放。（2）杭州后验年度人为二氧化碳排放量估计为4.65（±0.72）×10千克/年，表明不同的先验二氧化碳排放清单之间存在显著偏差。从多种产品得出的年度生物二氧化碳汇估计为-0.48（±0.16）×10千克。（3）计算得出的2021年碳中和能力为10.3%±3.4%，凸显了实现完全碳中和存在的巨大差距。考虑到由于森林年龄导致的生态系统碳汇潜在增加以及气候变化带来的不确定性，预计到2060年要实现完全碳中和的目标，至少必须减少65.2%-82.6%的人为二氧化碳排放。
