Uncovering divergences and potential gaps in local greenhouse gases emissions accounting and aggregation

Due to the contribution of cities to fight climate change, approaches and methodologies for GHG emissions inventories have multiplied; research is growing and numerous initiatives support local authorities in developing their local emissions inventories. The complexity of cities and the lack of data make necessary simplifications and assumptions in inventorying GHG emissions. Despite significant progresses in the compilation of inventories, there are still limitations and uncertainties on aggregation approaches. Therefore, it becomes crucial disclosing the methodologies underlying any emissions accounting frameworks, together with any simplifications and assumptions, with the aim to produce reliable support on local measures and data- driven decision-making in the form of a trustworthy emissions inventory. This study aims at identifying divergences and potential gaps in two approaches for GHG emission inventories at local level complementing the results of previous studies. It is intended as exemplificative of potential issues and limitations occurring in emissions accounting and aggregation. The two approaches are EDGAR (Emissions Database for Global Atmospheric Research), in place for the GHSL (Global Human Settlement Layer Urban Centre Database) (GHS-UCDB R2019A) and the BEI (Baseline Emission Inventory) approach developed within the Covenant of Mayors initiative. The main limitations uncovered here feature disagreements on spatial and time coverage, on the emissions sources and allocation and the types of emissions considered. Results show that despite the diverse approaches, data is comparable. Therefore, to identify and correct inconsistencies and to ensure the quality of emission inventories available to decision makers, analysis and consistent comparisons between results originating from different and independent methodologies are essential.