Challenges and opportunities towards improved application of the planetary boundary for land-system change in life cycle assessment of products

Life cycle assessment (LCA) can be used to translate the planetary boundaries (PBs) concept to the scale of decisions related to products. Existing PB-LCA methods convert quantified resource use and emissions to changes in the values of PB control variables. However, the control variable for the Land-system change PB, "area of forested land remaining", is not suitable for use in LCA, since it is expressed at the beginning of an impact pathway and only covers forest biomes. At the same time, LCA approaches for modelling the biogeophysical impacts of land use and land-use change are immature and any interactions with other types of environmental impacts are lagging. Here, we propose how the assessment of Land-system change in PB-LCA can be improved. First, we introduce two control variables for application in LCA; surface air temperature and precipitation, and we identify corresponding provisional threshold values associated with state shifts in four comprehensive biome categories. Second, we propose simplified approaches suitable for modelling the impact of land use and land-use change in product life cycles on the values of these two control variables. Third, we propose how to quantify interactions between the PBs for Land-system change, Climate change and Freshwater use for a PB-LCA method. Finally, we identify several research needs to facilitate full implementation of our proposed approach. (C) 2019 Elsevier B.V. All rights reserved.