Stable forest carbon stocks support current assumption of biogenic carbon neutrality in the case of European-manufactured beverage cartons

Abstract

Purpose Life cycle assessments (LCAs) of forest-based products, such as beverage cartons, generally demonstrate lower greenhouse gas emissions than fossil fuel-based alternatives and often contain the implicit assumption that removal of carbon dioxide (CO 2 ) by a growing forest and emission of CO 2 at the end of a product's life cancel each other out such that the net emission is zero. This study aims to test the validity of this assumption of biogenic CO 2 neutrality in relation to beverage cartons by examining whether carbon stocks of the source forests are stable. The fact that over 95 % of the cartonboard used in their manufacture is sourced from the boreal forests of Sweden and Finland provides a scenario with a straightforward relationship between forest and product thus avoiding issues surrounding the complexities of global supply chains. Methods The reviewed LCAs conclude that beverage cartons have lower greenhouse gas emissions than alternatives, although non-forest-derived components such as plastic caps and aluminium laminate often contribute disproportionately to those emissions. We discuss issues surrounding the assumption of biogenic CO 2 neutrality and explore the factors that influence carbon stocks in boreal forests that supply much of the raw material for beverage cartons.Results and discussion An analysis of published rates of carbon sequestration in the managed forests of Finland and Sweden reveals that forest carbon is stable under current harvest rates. This lends support to the assumption of biogenic CO 2 neutrality in the case of beverage cartons produced from these forests. We conclude that greenhouse gas emissions would not change if an LCA included forest carbon. However, future forest dynamics and thus carbon stocks are predicted to alter in response to climate change, for example, which will have knock on effects for greenhouse gas emissions from packaging derived from forests. Conclusions This review combines current thinking on inclusion of forest carbon in LCAs with an analysis of issues that will influence carbon stocks in managed forests. Although current assumptions of biogenic CO 2 neutrality are valid in the case of European-manufactured beverage cartons, we argue that this assumption needs to be explicitly addressed in LCAs. While there is no accepted methodology for integrating biogenic forest carbon uptake into LCA, our assessment of current trends in forest carbon stocks allows for assumptions of biogenic CO 2 neutrality to be tested, although our approach may not be practical for more complex supply chains.

Time dynamic climate impacts of a eucalyptus pulp product: Life cycle assessment including biogenic carbon and substitution effects

“…The study also provided new information on substitution factors, since pulp and paper or chemicals are often omitted in LCA studies, as stated by Soimakallio et al (2016), and geographical regions such as South America are rarely considered, as mentioned by Leskinen et al (2018). The climate effects found (Figures 3, 6, and 7) confirm findings in a review by O’Sullivan et al (2016) and in LCAs by Falkenstein et al (2010) and Markwardt et al (2017) dealing with climate effects of beverage cartons.…”

“…In a meta‐study of 20 life cycle assessments (LCAs), Falkenstein et al (2010) found that the beverage carton was usually attributed the lowest climate impact among functionally equivalent products such as glass or polyethylene terephthalate (PET) bottles. This has been confirmed by a later review on beverage cartons by O’Sullivan et al (2016) and a comparative LCA on beverage carton usage set in Northern Europe (Markwardt et al, 2017).…”

“…In fact, it is key to consider other impact categories apart from climate effects, such as water consumption (Ferraz et al, 2019) or biodiversity aspects (Pozo & Säumel, 2018) when assessing the environmental sustainability of a eucalyptus wood product system. Since only 8% of the managed forests in South America are under PEFC or FSC certification (Sikkema et al, 2017), there is an urgent need for scrutiny of environmental sustainability in LCA of the European wood supply (O’Sullivan et al, 2016).…”

Environmental Indicators for the Evaluation of Wood Products in Consideration of Site-Dependent Aspects: A Review and Integrated Approach

“…Further research demands mentioned in more recent studies mainly refer to the improvement of LCA, e.g., through the accounting of biotic resources [121], the consideration of the technical performance of building materials [180], the quantification of ecosystem services [139,157,164], the attributional allocation of long-lived products [190], the assessment of forest carbon dynamics including carbon tracking and soil carbon [143,145,165], the provision of interfaces to other modeling tools [191], the development of regional characterization factors for land use change [121], water balance [52,72] and biodiversity [72,171], and, finally, the increased application of such new approaches in case studies [123,138,154]. Moreover, the investigation of the influence of design decisions on the product quality and environmental performance of products is encouraged [82,192].…”

“…Wolfslehner et al (2013) [162] calculated the hardwood volume very precisely by means of a fixed radius sample plot and an angle count sampling. More often, researchers are forced to use less accurate estimations due to missing inventory data or knowledge about the true origin of the wooden material [163,164]. Only a completely documented chain-of-custody would allow a global traceability of wood.…”