Soils as sinks for carbon: the global context

Soil carbon sequestration could meet at most about one-third of the current yearly increase in atmospheric CO2-carbon, but the duration of the effect would be limited, with significant impacts lasting only 20-50 years. Coupled with this limited duration, increases in population and per-capita energy demand mean that soil carbon sequestration could play only a minor role in closing the difference between predicted and target carbon emissions by 2100. However, if atmospheric CO2 concentrations are to be stabilized at reasonable levels (450-650 ppm), drastic reductions in carbon emissions will be required over the next 20-30 years. Given this, carbon sequestration should form a central role in any portfolio of measures to reduce atmospheric CO2 concentrations over this crucial period, while new energy technologies are developed and implemented. International agreements, such as the Kyoto Protocol, encourage soil carbon sequestration and could be used to formulate soil carbon sequestration polices. Such policies need to take account of other environmental impacts as well as political, economic and societal needs, so that they form part of a raft of measures encouraging sustainable development. Of the carbon sequestration options available, those of a 'win-win' nature, that is, those that increase carbon stocks at the same time as improving other aspects of the environment, and those that protect or enhance existing stocks ('no regrets' implementation) show the greatest promise in meeting these goals.