Current rates of climate and atmospheric change are likely higher than during the last millions of years. Vegetation cannot keep pace with these changes and lags behind climate. We used a vegetation model to study how these lags are influenced by CO₂ and fire in Africa. Our results indicate that vegetation is most sensitive to CO₂ change under current and near-future conditions and that vegetation will be committed to further change even if CO₂ emissions are reduced and the climate stabilizes.