In 2024, PARIS contributed to raising the visibility of PARIS, AVENGERS and EYE-CLIMA at the European policy level, including through participation in a Working Group 1 (WG1) meeting and a Horizon Europe Clustering Event. This was followed in 2025 by an invitation for the PARIS project to present its latest results on greenhouse gas (GHG) verification and inverse modelling to the WG1 at their Annual GHG Inventories meeting, under the EU Climate Change Committee.

WG1 brings together the European Commission, the European Environment Agency (EEA) and its European Topic Centre, and representatives of EU Member States. The group provides a forum for exchanging information and coordinating work on national and EU GHG inventories, including reporting methodologies, data, quality assurance and quality control. For PARIS, the invitation provided an opportunity to discuss its findings directly with experts involved in the European inventory process. The presentation highlighted the complementary nature of bottom-up inventory approaches and top-down approaches based on atmospheric observations and inverse modelling. Comparing the two can provide an independent perspective on reported emissions, help identify differences and support improvements in emission estimates.

Examples presented included HFC-134a in the UK, where differences between inventory and top-down estimates prompted a review of inventory assumptions, and N₂O, where atmospheric observations revealed seasonal patterns that were not fully captured by process-based models. PARIS also presented cases where differences in geographical patterns and historical trends, such as for methane in the UK and SF₆ in Germany, provided useful information for further investigation. In Southern Germany, for example, atmospheric measurements and inverse modelling helped identify a significant SF₆ source that was not reflected in previous emission assumptions.

The exchange with WG1 illustrates how projects such PARIS can contribute to the ongoing dialogue between atmospheric scientists and national inventory experts. While the project is not responsible for national inventories, its results provide additional evidence that can be considered alongside existing inventory information. Continued collaboration between observation networks, modelling communities and inventory compilers will be important for developing more robust and transparent approaches to GHG reconciliation in Europe.