Reliable and accurate monitoring of CO₂ emissions is a cornerstone of effective climate change mitigation strategies. While traditional methods largely depend on ground-based measurements and bottom-up inventories, these approaches are often resource-intensive and prone to errors. Satellite technology has emerged as a promising alternative, but the challenge remains in distinguishing anthropogenic emissions from natural processes. The long atmospheric lifetime of CO₂ makes it difficult to pinpoint localized sources of emissions and track changes over time. Additionally, natural emissions and background concentrations can obscure signals from human activity. To overcome these hurdles, new, more advanced monitoring techniques are needed.

On October 18, 2024, a team from Tsinghua University published a review (DOI: 10.1007/s11783-025-1922-x) in Frontiers of Environmental Science & Engineering, presenting a novel method to monitor fossil fuel CO₂ emissions by utilizing satellite observations of NO₂. This method offers a more reliable and scalable solution for tracking emissions, from localized sources like power plants to broader national levels.

The review introduces two primary methodologies to use NO₂ as a proxy for CO₂ emissions, taking advantage of its shorter atmospheric lifetime and enhanced detectability. The first method, the plume-based approach, uses NO₂ observations to locate and validate CO₂ plumes, providing a precise way to identify emissions from point sources such as power plants and industrial facilities. By tracking the movement of NO₂ plumes, researchers can more accurately determine the origin and magnitude of CO₂ emissions. This method is particularly useful in urban environments with multiple emission sources, as it allows for the differentiation of emissions from various facilities.

The second method, the emission ratio-based approach, involves estimating NO_x emissions from NO₂ data and converting these estimates into CO₂ emissions using known CO₂-to-NO_x emission ratios. This technique is especially effective for larger spatial scales, such as national or regional assessments, where direct CO₂ observations might be compromised by high background concentrations. By incorporating emission ratios, this method accounts for variations in fuel types and combustion processes, offering a more reliable estimation of CO₂ emissions. The study also addresses the uncertainties inherent in these methods, including structural uncertainties in the relationship between NO₂ and emissions, as well as data-related challenges like retrieval errors and the accuracy of prior emissions inventories. To reduce these uncertainties, the researchers recommend the deployment of next-generation satellites with enhanced capabilities and the development of more sophisticated inversion systems.

Dr. Bo Zheng, an associate professor at Tsinghua University and a leading author of the study, commented, "This research marks a significant leap forward in our ability to monitor and verify CO₂ emissions. By utilizing NO₂ as a proxy, we can achieve much greater accuracy and reliability in emission estimates, which is crucial for implementing effective climate policies."

The study's findings have far-reaching implications for global climate policy and environmental management. Accurate emissions monitoring is critical for countries to assess their progress toward meeting their climate commitments under the Paris Agreement. This new technology can support the development of more targeted and effective mitigation strategies, strengthening international efforts to combat climate change. Moreover, it provides researchers and policymakers with a valuable tool for understanding CO₂ emission dynamics and their environmental consequences, paving the way for more informed decision-making in climate action.

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References

DOI

10.1007/s11783-025-1922-x

Original Source URL

https://doi.org/10.1007/s11783-025-1922-x

Funding information

This work was supported by the National Natural Science Foundation of China (No. 42105094).

About Frontiers of Environmental Science & Engineering

Frontiers of Environmental Science & Engineering (FESE) is the leading edge forum for peer-reviewed original submissions in English on all main branches of environmental disciplines. FESE welcomes original research papers, review articles, short communications, and views & comments. All the papers will be published within 6 months after they are submitted. The Editors-in-Chief are Academician Jiuhui Qu from Tsinghua University, and Prof. John C. Crittenden from Georgia Institute of Technology, USA. The journal has been indexed by almost all the authoritative databases such as SCI, EI, INSPEC, SCOPUS, CSCD, etc.