Climate Change Impacts Due to Biogenic Carbon: Addressing the Issue of Attribution Using Two Metrics With Very Different Outcomes

Although not without its critics, considerable recognition has been given to the climate cooling benefits provided by storing carbon from biomass in various storage pools. However, it has recently been found that depending on the storage pool/period and source of biomass, the associated climate impacts may be a burden or a benefit. It is important that carbon accounting schemes and life cycle assessment practitioners take these carbon/CO₂ flux dynamics and the climate impacts that they create into consideration. In this work we illustrate these climate impacts with a Norwegian case study using a material flow analysis of the biogenic carbon in harvested wood products derived from a 2006 harvest year. We illustrate the dynamic carbon balance over time and show how the climate impacts can diverge greatly between two well-known climate impact metrics: global warming potential (GWP) and global temperature potential (GTP). We also show how these climate impacts can be attributed to contributing parties with an example of a glue laminated beam value chain which is stored in a long-lived building. We discuss the associated attribution issues that will inevitably arise and we offer recommendations on how best to minimize them.