There is scope for land‐use changes to increase or decrease CO 2 concentrations in the atmosphere over the next century. Here we make simple but robust calculations of the maximum impact of such changes. Historical land‐use changes (mostly deforestation) and fossil fuel emissions have caused an increase in atmospheric concentration of CO 2 of 90 ppm between the pre‐industrial era and year 2000. The projected range of CO 2 conc...

Small reported growth enhancement factors based on analyses of forest inventory data from the eastern USA ( Caspersen et al . 2000 , Science, 290, 1148–1151) have been interpreted as evidence against CO 2 fertilization in natural forests. We show to the contrary that growth enhancement in response to rising CO 2 , as found in ecosystems with experimental CO 2 enrichment and implemented in terrestrial ecosystem models, is consi...