The reporting of national greenhouse gas (GHG) emission inventories is a crucial element in the 2015 Paris Agreement under the United Nations Framework Convention on Climate Change (UNFCCC). However, the reported emissions carry substantial uncertainties and lack independent verification. The AVENGERS (Attributing and Verifying European and National Greenhouse gas and aerosol Emissions and Reconciliation with Statistical bottom-up estimates) project brings together European experts to establish top-down techniques in support of the verification of national greenhouse gas (GHG) inventories. AVENGERS will make use of atmospheric inverse modelling and data assimilation, remote sensing, environmental monitoring and observation, terrestrial ecosystem modelling, policy and stakeholder interaction together with national inventory compilers in order to improve the methods and approaches currently used in GHG emission inventory reporting. AVENGERS will advance the top-down approach for quantifying GHG and aerosol emissions by adding additional tracers (e.g. radiocarbon, co-emitted species, black carbon), as well as reconcile and integrate approaches into a joint bottom-up and top-down framework. Based on the reconciliation, AVENGERS will prepare good-practice guidelines for use of atmospheric inverse models as well as develop a Flexible Inversion Tool for Inventory Compilers (FIT-IC). Knowledge and outcomes are provided for use to policy and societal stakeholders and replicable outside of the chosen target areas of the project (Europe with a focus on Germany, Italy, Sweden, Switzerland, and The Netherlands). The uniqueness of the consortium lies in the combination of the required scientific expertise with full partner presence of official reporting agencies from exemplary EU countries facilitating the transfer of knowledge to key stakeholders (the national reporting agencies and international organisations such as UNFCCC, WMO) in the field.
