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Carbon neutrality
Carbon neutrality, carbon offset and carbon trading schemes
A number of schemes are currently operating which offer individuals and organisations the opportunity to have trees planted on their behalf with the aim of offsetting emissions of GHGs. An estimate is made of the carbon sequestered over the life time of the woodland and this is marketed as a carbon credit to offset emissions resulting from specified activities of an individual or organisation.
Concerns have been raised over schemes that award credits in advance of the carbon being sequestered. There is also a question mark over the long-term future of woodlands created for this purpose, because of uncertainties over future land management or the occurrence of natural events such as storms and droughts or the effects of climate change itself. Availability of land for afforestation limits the potential for individuals or organisations to take up these schemes, both in the UK and globally.
One of the examples most frequently encountered is that of ‘carbon-neutral car use’. As a rough guide, the carbon sequestered by half a hectare of woodland over one rotation can compensate for the CO2 emissions associated with car fuel consumption during an average driver’s lifetime: this sounds a small area, but it should be borne in mind that with 30 million registered drivers in the UK, three-quarters of the land area of the nation would have to be afforested to make car use alone carbon-neutral.
What is the sequestration potential of UK forests?
Clearly, forest carbon sequestration alone cannot be used to offset GHG emissions from fossil fuel consumption and industrial processes associated with contemporary ways of living and working. However, the carbon sink associated with UK forests could make a useful contribution as policies and initiatives are developed to reduce GHG emissions.
The forest estate of the UK covers an area of 2.8 million hectares or 11.6% of the land surface, and equivalent to an area about the size of Wales. The biomass which constitutes these forests contains about 150 MtC, which is roughly equal to one year of CO2 emissions from burning fossil fuels and certain industrial processes in the UK. For the UK to become carbon-neutral (in terms of CO2 emissions at current rates) through afforestation alone, it would be necessary to create 50 million hectares of forest that maintained an average rate of carbon sequestration of around 3 tC/ha/yr over the period from establishment to the old-growth phase. This is approximately double the land area of the UK. Moreover, once the forests attained the old-growth phase (perhaps after 100 years) they would stop acting as a carbon sink.