Differences in land-based mitigation estimates reconciled by separating natural and land-use CO₂ fluxes at the country level

Anthropogenic and natural CO₂ fluxes on land constitute substantial CO₂ emissions and removals but are usually not well distinguished in national greenhouse gas reporting. Instead, countries frequently combine natural and indirect human-induced CO₂ fluxes on managed land in their reports, which diminishes their usefulness for designing policies consistent with climate mitigation targets. Here, we separate natural and land-use-related CO₂ fluxes from national reports in eight countries using global models to improve the assessment of attribution of terrestrial CO₂ fluxes to direct anthropogenic activities. In most investigated countries, the gap between model-based and report-based CO₂ flux estimates is reduced if natural and indirect human-induced CO₂ fluxes on managed land are considered. Further examinations show that remaining differences are linked to country-specific discrepancies between model-based and report-based estimates. Separating natural and land-use-related CO₂ fluxes at national scales supports a fair burden sharing of climate mitigation across countries and facilitates the assessment of land-based mitigation ambitions.