Simulation modelling reported previously of the effect of allocating land to two carbon absorption processes is refined and carried further. The processes are short rotation biofuel production and long rotation plantation forestry acting as a buffer stock of carbon. The modelling procedure is designed to show the effect relative to published scenarios. It is shown that, up to a 70-year time horizon, the profile of reducing carbon in atmosphere in the published scenarios is brought forward-and reaches a lower final level-as the result of vigourous land allocation policy. This is in line with previous work. A first assessment of costs suggests that, after taking credit for sales of products, these improvements to published scenarios are available at very low cost or at a profit.