As the world finally wakes up to the task ahead in mitigating climate breakdown, there is a lot of discussion about trees and urging reforestation to help reduce atmospheric carbon and limit global warming. Many commentators refer to trees using terms like “miracle machines that build themselves and convert CO2 to oxygen.”
Of course this is true, we need to plant trees on an unprecedented scale and pace if we are to have any chance of meeting the IPCC’s targets for 2030. However, while forests are great carbon stores, once the trees are mature, their carbon emissions balance the absorption leading to a net zero contribution to greenhouse gas (GHG) reduction. For a fast- growing spruce or pine, this takes about 50-80 years, for an oak, this takes around 200-250 years.
If we are serious about using trees to combat climate change, we need to therefore remove the trees once they are mature, store the timber and plant new trees. One of the best long-term stores for timber is in buildings. We can construct buildings that last over 100 years using timber and using modern forms of engineered timber, such as glulam and cross-laminated timber (CLT). We can also replace materials like concrete and steel, which have large carbon footprints – together these two materials are responsible for 15 percent global CO2 emissions.