Inverse modelling and verification of carbon fluxes using satellite observations

Objective

Carbon dioxide (CO2) is the most significant long-lived greenhouse gas driving anthropogenic climate change. While progress has been made in reducing fossil fuel emissions, major uncertainties remain in the carbon cycle due to limited knowledge of natural sources and sinks. Terrestrial ecosystems absorb nearly 30% of annual anthropogenic CO2 emissions, yet their variability and permanence are poorly constrained, limiting the reliability of climate projections and mitigation strategies. In Europe, despite dense observational networks and emissions inventories, significant gaps persist in CO2 flux estimates, constraining the capacity to verify national and regional emissions. Ground-based flux towers provide accurate local information but are costly and spatially restricted. Satellite remote sensing offers unprecedented opportunities to overcome these limitations, with the upcoming CO2M mission expected to deliver high-resolution atmospheric CO2 data. When combined with atmospheric transport models, these data enable more robust assessments of spatial and temporal flux patterns. However, current systems often fall short in producing regionally resolved CO2 budgets robust enough for EU policy verification. The INVERSO project (INverse modelling and VERification of carbon fluxes using Satellite Observations) will address these gaps by integrating next-generation satellite products (e.g., CO2M) with updated prior flux information through the IMI inversion framework, coupled with WRF-Chem transport simulations. Independent validation will use flux towers and drone-based hyperspectral observations from the GHG-MONITOR project. By providing high-resolution, policy-relevant CO2 flux estimates, INVERSO will strengthen monitoring, reporting, and verification (MRV) systems. Although developed for Denmark, its scalable methodology will contribute to EU-wide climate neutrality efforts.