奥地利国际应用系统分析研究所 Gidden Matthew J. 和 Gasser Thomas 团队的最新研究提出了将气候情景与排放清单相结合，会改变全球基准的新见解。该研究于2023年11月22日发表于《自然》杂志上。

研究团队使用最先进的方法和陆地碳循环模拟器，将政府间气候变化专门委员会(IPCC)评估的减缓路径与国家温室气体地理信息系统进行对比。研究结果发现，当以《国家温室气体排放清单指南》进行计算时，关键的全球减排基准变得更难实现，需要更早的二氧化碳净零排放时间和更低的累积排放量。

此外，碳肥化等不断削弱自然除碳过程，也可能掩盖人为的陆地除碳努力，其结果是，到 2100 年，《国家温室气体排放清单指南》中的陆地碳通量最终可能成为排放的主要来源。研究结果对《全球评估》很重要，表明各国需要提高各自气候目标的集体决心，以保持与全球温度目标的一致。

据介绍，评估在实现《巴黎协定》方面取得的全球进展，需要对照模拟的减缓途径，持续衡量总体国家行动和承诺。然而，《国家温室气体排放清单指南》(NGHGIs)和人为排放的科学评估遵循不同的陆地碳通量核算惯例，导致目前的排放估计值存在很大差异，这一差距将随着时间的推移而扩大。

附：英文原文

Title: Aligning climate scenarios to emissions inventories shifts global benchmarks

Author: Gidden, Matthew J., Gasser, Thomas, Grassi, Giacomo, Forsell, Nicklas, Janssens, Iris, Lamb, William F., Minx, Jan, Nicholls, Zebedee, Steinhauser, Jan, Riahi, Keywan

Issue&Volume: 2023-11-22

Abstract: Taking stock of global progress towards achieving the Paris Agreement requires consistently measuring aggregate national actions and pledges against modelled mitigation pathways. However, national greenhouse gas inventories (NGHGIs) and scientific assessments of anthropogenic emissions follow different accounting conventions for land-based carbon fluxes resulting in a large difference in the present emission estimates, a gap that will evolve over time. Using state-of-the-art methodologies and a land carbon-cycle emulator, we align the Intergovernmental Panel on Climate Change (IPCC)-assessed mitigation pathways with the NGHGIs to make a comparison. We find that the key global mitigation benchmarks become harder to achieve when calculated using the NGHGI conventions, requiring both earlier net-zero CO₂ timing and lower cumulative emissions. Furthermore, weakening natural carbon removal processes such as carbon fertilization can mask anthropogenic land-based removal efforts, with the result that land-based carbon fluxes in NGHGIs may ultimately become sources of emissions by 2100. Our results are important for the Global Stocktake, suggesting that nations will need to increase the collective ambition of their climate targets to remain consistent with the global temperature goals. Aligning the IPCC-assessed mitigation pathways with the national greenhouse gas inventories shows that key global mitigation benchmarks become harder to achieve, requiring achieving earlier net-zero and lower cumulative emissions.

DOI: 10.1038/s41586-023-06724-y

Source: https://www.nature.com/articles/s41586-023-06724-y