The United Nations Framework Convention on Climate Change and the Kyoto Protocol recognise the role of carbon sinks, such as forests, in offsetting greenhouse gas emissions and impose responsibilities on Parties to protect and enhance carbon sinks. All plants sequester carbon through the process of photosynthesis; trees are particularly effective because of their large biomass and long life. Forestry-related activities can promote and enhance the role of forests in carbon sequestration, via afforestation, reforestation, reducing deforestation and the application of appropriate forest management techniques. There are other examples of possible carbon sinks that can be enhanced by changes in land management. One such option that has been discussed involves reducing tillage in arable croplands. Arable soils usually have very low carbon stocks because of intensive management involving ploughing and other disturbances to the land. If the intensity of these operations can be reduced, it is possible that the carbon in the soil will increase.
It is not feasible for the UK to become ‘carbon neutral’ through afforestation alone. It is estimated that to do this would require creation of some 50 million hectares of forest – approximately twice the land area of the UK. There is also a potential problem with trying to achieve carbon neutrality through reliance on carbon sinks due to the creation of forests or changes to land management: The carbon sink is reversed (becomes a carbon source) if the carbon stocks are not protected indefinitely. Some scientific studies have indicated that sequestering carbon now but allowing the carbon to be released again later has a more serious impact on the climate than not sequestering the carbon in the first place.
The potential gains from carbon sequestration via forestry are likely to be small relative to total carbon emissions. However, the carbon sink associated with UK forests can make a contribution to the range of policies to reduce greenhouse gas emissions. Because of the short-term and potentially reversible benefits of carbon neutrality measures based on forestry, one option might be to involve them in projects that deliver a 'package' of benefits, for example providing a source of renewable wood fuel or products in the longer term.
