A framework for modelling indirect land use changes in life cycle assessment

Abstract

Around 9% of global CO₂ emissions originate from land use changes. Often, these emissions are not appropriately addressed in Life Cycle Assessment. The link between demand for crops in one region and impacts in other regions is referred to here as indirect land use change (iLUC) and includes deforestation, intensification and reduced consumption. Existing models for iLUC tend to ignore intensification and reduced consumption, they most often operate with arbitrary amortisation periods to allocate deforestation emissions over time, and the causal link between land occupation and deforestation is generally weakly established. This paper presents the conceptual framework required for a consistent modelling of iLUC in Life Cycle Assessment. It reports on a novel and biophysical iLUC model, in which amortisation is avoided by using discounted Global Warming Potentials (GWPs). The causal link between demand for land and land use changes is established through markets for land’s production capacity. The iLUC model presented is generally applicable to all land use types, crops and regions of the world in typical LCA decision-making contexts focusing on the long-term effects of small-scale changes. The model’s strengths and weaknesses are discussed.