Urban GHG accounting: Discrepancies, constraints and opportunities

To date, many cities have engaged in efforts to become more sustainable. These efforts often are translated into measures to reduce their greenhouse gas (GHG) emissions, leading to a proliferation of standards and methods. Discrepancies exist between these various accounting approaches in terms of the definition of system boundaries, allocation procedures, quality of data, and the reporting and verification of results. This paper examines some of the most important theoretical and practical issues and challenges of urban-related GHG accounting and highlights how existing approaches deal with these. Three different GHG emission accounting standards are compared and critically analysed: the Global Protocol for Community-Scale Greenhouse Gas Emissions (GPC), Bilan Carbone and ISO 14064-1:2018. The Organizational Environmental Footprint (OEF) and a previous analysis about footprinting performed by the European Commission are used as analytical lenses. Based on this analysis, suggestions are made for enhancing comprehensiveness and transparency, and providing guidelines for driving cities towards a more low-carbon path. Practice relevance: This critical analysis shows that each method has strong points, but practical issues remain for urban stakeholders undertaking GHG emissions inventories. First, the uniqueness of each urban system needs to be addressed in the goal and scope phase in order to provide meaningful terms of comparison between cities. The creation of different categories to provide similar clusters of cities would enable a more meaningful cross-city comparison as well as a proper formulation of targeted policies. Second, the inclusion of a life-cycle perspective in GHG accounting is essential for avoiding the risk of burdenshifting. Both production and consumption approaches are crucial in supporting the objectives of decarbonisation and the carbon neutrality of cities. If both perspectives are not acknowledged, 'climate neutral' targets can be misleading and impact negatively on decision-making and behavioural change of producers and consumers.