Accurately estimating greenhouse gas (GHG) fluxes remains a central challenge in climate science and climate policy. Estimation of emissions from atmospheric data, known as “inverse modelling” is playing an increasingly important role in the evaluation of national inventories.
Fluxy is a new visualisation and analysis tool that helps compare GHG flux estimates from different atmospheric inversion models. Designed to support scientific research, Fluxy provides a way to explore differences and similarities in inverse model results for key gases such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O).
The tool is developed under the EU Horizon Europe project, PARIS, with contributions from the University of Bristol, Empa, and the UK Met Office. It is openly available via GitHub. The core functionality is built on common NetCDF data formats and supported by a Jupyter notebook interface, enabling streamlined user interaction and quick generation of standardised graphs. The data formats and notebook design are a collaborative effort between PARIS and its sister projects AVENGERS and EYE-CLIMA.
Scientific Functionality and Technical Scope
Outputs from various inversion models—such as InTEM, RHIME, and ELRIS —can be compared, and aggregation is supported at multiple spatial and temporal scales, including monthly, seasonal, and annual periods, and at national and regional levels (e.g. EU regions). This flexibility allows researchers to assess inter-model consistency in various contexts and interrogate the reasons for persistent discrepancies in inversion results.
The tool supports comparative analysis and visualisation of:
- Posterior and prior flux estimates, with associated uncertainties and comparison to UNFCCC reporting
- Spatial flux maps, aggregated by country or region
- Time series of mole fractions, observed and modelled (posterior and prior), including baseline and regional contributions
- Comparison statistics for mole fraction simulations including display in Taylor diagrams
- Analysis of components of model-data-mismatch uncertainties utilised in the inversions
Upcoming features include spatial regridding and the ability to compare sectoral flux estimates.
Supporting Climate Science and Policy
FLUXY serves as a bridge between complex scientific modelling and climate policy needs. It methods to compare top-down model estimates and bottom-up national inventory data, which is increasingly important in the EU’s GHG inventory evaluation process. It allows researchers, inventory experts, and institutional stakeholders to compare GHG fluxes from different inversion models in a standardised format. By doing so, it supports transparency and reproducibility. The tool addresses a key gap in the inverse modelling community: the lack of a standardised, open-source tool for post-processing and comparing inversion results. It:
- facilitates collaborative intercomparison exercises
- enhances transparency and reproducibility
- enables structured evaluation of inversion system outputs
- supports cross-disciplinary communication between scientists and policymakers
Fluxy provides accessible visualisations and insights into modelled GHG fluxes, supporting informed decision-making and identifying inconsistencies between reported emissions and model-based estimates. It is of added value in e.g. settings such as the Climate Change Committee’s Working Group 1 (WG1), where national GHG inventory coordinators and institutional representatives assess reported data. The output of WG1 directly supports the production of the EU GHG inventory, a critical tool for monitoring progress towards EU climate targets.
For national GHG inventories, Fluxy can serve as a helpful tool for validating and improving them. It can help facilitating collaboration between model developers, inventory compilers, and policymakers, and support EU’s broader efforts to strengthen climate transparency and accountability.
Interested in contributing? Contact us through github or at horizoneuropeparis@gmail.com
