Over the course of the project, all partners supported the key objectives of VERIFY through activities ranging from model development, GHG flux estimations, and GHG flux synthesis while also including synergies between science and inventory communities. The main achievements are:
• Networking meetings between the research community and the national inventory compilers and active collaboration with international programs (contribution to the GHG synthesis of the Global Carbon Project, to WMO-IGIS initiatives, to COP related events, …).
• Process-based and statistical model simulations of terrestrial ecosystem CO2/CH4/N2O fluxes over Europe, at high spatial resolution for CO2 (~10 km over the last century).
• New atmospheric regional inversions for natural CO2/CH4/N2O fluxes (up to 2021 for CO2) and construction of a community inversion framework as the backbone of a transparent, internationally-shared future GHG monitoring system.
• New continental high-resolution maps (~6 km resolution) of anthropogenic emissions of CO2 and co-emitted species for Europe (up to 2019).
• Two inversion estimates of the annual CO, NOx and CO2 anthropogenic emissions in Western Europe based on satellite CO and NO2 data.
• Deployment of instruments and acquisition of new data, through both campaigns in the Rhine Valley and St Petersburg area, to study the correlation between anthropogenic CO2 and co-emitted species.
• First GHG flux synthesis over Europe for CO2, CH4 and N2O comparing the observation based estimates with the national inventories (including the creation of Factsheets synthesizing emissions).
• Construction of a framework (i.e. pre-operational system) to provide a yearly update of the GHG flux synthesis for all EU countries (covering the past two decades up to the previous year).
• Construction of a database to host VERIFY datasets and of user-friendly visualization tools (time series and mapping facilities) to explore recent trends in GHG fluxes.
• Analysis of the drivers of the EU GHG trends and contribution to the analysis of the COVID-19 related changes in anthropogenic GHG emissions.
• A report on the research needs to further improve observation-based GHG flux estimates (bottom up and top down approaches).
