We hope I Dig Trees will make a hugely positive impact, both in terms of society and CO2. But quantifying CO2 impact isn’t a simple equation, because trees make a positive difference over their entire lifetime and existing methodologies are designed for large forests.
It depends on the tree, the location and the lifetime of the tree. UK native deciduous broadleaf trees – the varieties we’re planting – do a particularly good job. According to the carbon-counting professionals at Carbon Footprint (a provider of environment and carbon management services for business):
"The amount of CO2 a tree will offset depends on many factors, such as the type of tree, where it is planted and the amount of room it has to grow. On average, one broad leaf tree will absorb in the region of 1 tonne of carbon dioxide during its full life-time (approximately 100 years)."
In the first year of our programme we planted over 158,000 trees. If each tree – over its 100-year lifetime – absorbs 1 tonne of CO2 and we assume a 50% survival rate on the trees planted, we’re looking at a minimum of 79,000 tonnes of carbon* saved as a result of the 2015/16 I Dig Trees programme. This year we aim to plant over 250,000 trees by April 2017, increasing the potential amount of carbon saved to 125,000 tonnes.*
However, not every tree will survive and there may be differences based on so many of our trees being planted in urban areas. We are working with TCV, the Forestry Commission and others to improve our ability to measure the CO2 impact of green spaces.
I Dig Trees is about more than emissions. We’ll make a positive CO2 impact, yes, but almost as important is the impact on the human spirit – engaging with nature, volunteering for the good of the community, getting a little sweaty and a little dirty.
*Based on Carbon Footprint’s calculation of 1 tonne of CO2 per native deciduous broadleaf over its 100 year lifetime and a 50% survival rate of the trees planted.