Urban areas are significant contributors to global greenhouse gas (GHG) emissions. Detailed understanding of urban GHG emissions, including their temporal and spatial dynamics, is critical for finding effective emissions reduction strategies. This session will explore the cutting-edge methodologies used to quantify and analyze urban GHG emissions, offering a comprehensive view of their sources, sinks, and the environmental factors that influence them. In addition to anthropogenic emissions, the session will emphasize the importance of incorporating biogenic components into GHG assessments. This holistic approach not only reduces uncertainties in emission estimations but also highlights the role of urban vegetation and soil in carbon sequestration. The integration of biogenic factors is essential for developing accurate urban carbon budgets and informing sustainable urban planning. There are multiple different approaches, from micrometeorological measurements and isotope analysis to urban-scale modelling, that are being employed to understand urban GHG emissions. Novel city-wide monitoring networks and measurement platforms such as mobile observations and ground-based remote sensing are also emerging. This session brings together diverse methodologies used to enhance our understanding of urban GHG budgets, their emissions and sinks, and dependencies on different environmental factors at different scales. We invite contributions that utilize conceptual, experimental, observational, or modelling approaches, source apportionment in urban areas and related uncertainties, and studies on how the different observational and modelling methodologies can be used to support climate action plans in various cities.