The Paris Agreement on Climate sets the international objective of reducing greenhouse gas (GHG) emissions to keep climate warming well below two degrees. However, quantifying past and present GHG sources and sinks and predicting their future remains a substantial challenge, largely due to uncertainties in observing, attributing, and modelling GHG fluxes from regional to global scales. National- and sector-level budgets are particularly critical, as they provide the basis for assessing progress towards nationally determined contributions (NDCs) and inform mitigation policies.
This session brings together studies that improve understanding and quantification of budgets, trends, variability and drivers of major GHGs (CO₂, CH₄ and N₂O) across land, ocean and atmosphere, while also advancing the inventory and Monitoring Reporting Verification (MRV) foundations needed for robust reporting, such as baseline definition, refinement of emission factors, uncertainty quantification, and scaling from site-level observations to national estimates.
Contributions across land, ocean and atmosphere are welcome, including land-use and forest-focused work where baselines and emission factors substantially influence national GHG accounts. We welcome diverse approaches, including (national) emissions inventories, field and remotely sensed observations, terrestrial and ocean biogeochemical modelling, Earth system modelling, atmospheric inverse modelling, and data-model integration. We encourage contributions integrating different datasets and approaches that provide new insights on processes influencing GHG budgets and trends across temporal scales, particularly where implications for reporting and policy are in focus.