By Dan Lazarou-West
As a forester, I can at least take some pleasure in knowing that part of my job is helping to combat climate change. However – and related to an earlier blog regarding plastic use in woodlands – how much of a difference can we make? The following may make for grim reading but small changes to how we view carbon sequestration can make a big difference. So, can enough carbon be stored in forests to affect the rate of global warming in the UK?
If we look at just vehicle emissions in the UK, we can see how many hectares of woodland we would need to plant to help to offset carbon (see table below). But big is a hectare, it’s roughly the same size as an international rugby field (some of us may not want to visualise a rugby field after some of the recent 6 nations results).
The table above is making some assumptions. The annual carbon emission is based on a given average of the vehicles on the road with a fuel consumption of 31 miles to the gallon (in the case of cars). The yield classes stated would require the trees to be planted in well drained fertile soils (soils of this type are generally used for agriculture) and the figures assume the undertaking of normal sylvacultural operations such as thinning and that the timber is harvested at a time of mean annual increment. Clearly it is even more advantageous if the lifetime of the wood product is equal to or exceeds the average rotation (i.e. construction timber) as the carbon is then locked up within the product. In addition, the soil itself locks up carbon and on good fertile soil sites as much as 1.75 tonnes of carbon per hectare per year may be locked up. However, this carbon is all too easily released into the atmosphere if the soil is disturbed.
Sadly, though, even if you look at figures of cars on the road back in the start of the century and consider all other fossil fuel emissions and the amount of carbon emitted per person in the UK, an estimated 51 million hectares of conifers would need to be planted – twice the land area of the UK. So clearly forestry is not the only solution to the problem. Although, we may want to start putting those rugby fields to good use by planting them up sooner rather than later.