BC launched its Mass Timber Action Plan, partly on the premise that building with wood has a lower carbon footprint than construction alternatives such concrete and steel. Meanwhile, environmental groups continue to protest against old growth logging, in part based on claims about logging’s carbon footprint. Puzzled by this apparent contradiction in climate claims, I took a deeper look at the science underlying the carbon impacts of forestry and wood use. …Indeed, studies have shown buildings made with mass timber, emit 30 to 40 per cent less carbon from their construction than their concrete and steel counterparts. …Old growth forests contain stores of carbon absorbed from the atmosphere. Given that fact, can BC forest products, including mass timber, actually be considered carbon-friendly?
The argument against old growth logging is that the disruption caused by harvesting mature forests could release more carbon than would be absorbed by the younger trees that will grow in their place. …Researchers at Oregon State University and the US-based CORRIM consortium …found that clearcut forests initially become a carbon source. However, after about 12 years the young saplings catch up in their carbon absorption capabilities, bringing that forest to carbon-neutral. At about 30 years trees start to add a lot of volume and…turn the forest into a net carbon sink. …The verdict? It is best to have a mix of both old and young forests. …The challenge lies in pacing the rate of logging so that the area of very young forests emitting more carbon than they sequester is balanced by a larger area of carbon-hungry teenage-to-middle-aged forests. …In a nutshell, the models suggest that harvesting old growth can be carbon friendly, especially if it is used in products like mass timber.