PARIS has a strong focus on the quantification and reconciliation of greenhouse gas (GHG) emissions, and highlighted the ongoing efforts to reduce uncertainties in emissions estimates through both observational and modeling approaches at the EGU 2025. Thomas Röckmann introduced the project and presented the progress of the consortium (presentation). Key presentations and contributions of colleagues from the PARIS consortium addressed recent trends in atmospheric methane, improvements in inverse modeling of HFC and N₂O emissions, and the integration of isotopic data to refine source attribution. The Union Symposium “What’s happening to atmospheric methane and how can we mitigate the rise?” brought together experts across disciplines to discuss observed increases in atmospheric CH₄, advances in isotopic measurement techniques, and implications for mitigation strategies. 

A recurring theme across multiple sessions was the reconciliation of top-down (atmospheric inversion) and bottom-up (inventory-based) emission estimates. These contributions highlighted discrepancies between reported and observed emissions across Europe, the methodological challenges involved, and the potential for integrated approaches to enhance transparency and accuracy in national reporting. Together with the sister projects EYE-CLIMA and AVENGERS, PARIS organised a dedicated splinter meeting about the joint forces of the Horizon Europe project group and the shared objectives about improving emissions data to support the implementation of the Paris Agreement. The projects provide GHG and aerosol emissions estimates using observation-based methods to improve estimates of national emissions and national greenhouse gas inventories (NGHGIs). They collaborate with NGHGI stakeholders, government entities, NGOs, and policy makers to further explore strategies for verification and harmonisation of emission estimates for key climate forcers.

The presentations also showcased new developments in continuous isotope measurements and sampling methodologies, with several studies emphasizing the importance of vertical resolution and multi-isotopologue analysis. These techniques are increasingly critical for distinguishing between anthropogenic and natural sources of CO₂ and CH₄, and for validating inversion models. Overall, the EGU 2025 presentations underscored the importance of coordinated observational networks, high-resolution modeling, and methodological standardization in supporting evidence-based climate policy and emissions monitoring.

Find an overview of related presentations and sessions HERE