Framework for including national-level LULUC emissions and removals in the GWP of agricultural and forestry products in LCA

Abstract

Land use and land use change (LULUC) encompasses carbon stock changes in living biomass, dead organic matter, and soil organic carbon, causing LULUC-related greenhouse gas (GHG) emissions and removals reported as global warming potential (GWP_LULUC). Regardless of the realised importance, accounting for LULUC in life cycle assessment (LCA) is challenging due to its complex nature and gaps in internationally recommended approaches. As a result, LULUC methods in LCA remain variable and often incomplete. Here, we aim to improve the inclusion of the national-level LULUC emissions and removals in LCA by providing a framework aligning with the National GHG Inventories. That is to enhance the practicality and use of open-access national-level LULUC data. Furthermore, we applied the framework to cropland and forest land, to demonstrate the effect of LULUC emissions and removals on the GWP of two typical Finnish agricultural and forestry products – oats and harvested softwood of Norway spruce. The developed framework provides a comprehensive consideration of carbon stocks, accounts for net carbon removals, and distinguishes mineral and organic soils. The case study results showed that consideration of LULUC increased the GWP of oats and mainly decreased the GWP of harvested softwood. The results highlight the importance of considering organic soils separately from mineral soils in areas high in organic soils, such as Finland. It is also important to consider net carbon removals of forest land, as they have potential to mitigate GWP. The framework includes LULUC emissions and removals based on national-level average data, but it can be specified by data regarding the share of organic soils and land use history. Including LULUC emissions and removals improves the completeness and accuracy of LCA. In the developed framework, the inclusion of LULUC is done by utilizing annually updating national-level GHG inventory data, to avoid partial or double counting and to enhance practicality. Special focus needs to be put on the share of organic soils on the production chain, which needs to be specified in areas high in organic soils such as Finland.