Fluxes from deforestation, changes in land cover, land use and management practices (F.sub.LUC for simplicity) contributed to approximately 14 % of anthropogenic CO.sub.2 emissions in 2009-2018. Estimating F.sub.LUC accurately in space and in time remains, however, challenging, due to multiple sources of uncertainty in the calculation of these fluxes. This uncertainty, in turn, is propagated to global and regional carbon budget estimates, hindering the compilation of a consistent carbon budget and preventing us from constraining other terms, such as the natural land sink. Uncertainties in F.sub.LUC estimates arise from many different sources, including differences in model structure (e.g. process based vs. bookkeeping) and model parameterisation. Quantifying the uncertainties from each source requires controlled simulations to separate their effects.