Globally-differentiated land use flow inventories for life cycle impact assessment

Abstract

LCA can be a useful methodology to assess land use impacts, e.g. change in soil quality and impacts on biodiversity. Over the past five years, several life cycle impact assessment (LCIA) methods have emerged, with specific focus on including spatial differentiation. Although normalisation is an optional step in LCIA, the increasing emergence of land use indicators and LCIA methods should be accompanied by corresponding normalisation references to enable putting assessment results in perspective. This requires building consistent global inventories of land use flows that can accommodate the level of spatial differentiation of the methods and include both land occupation and transformation flows. To the authors’ knowledge, such inventories however are currently missing. Here, we aim to bridge this gap and develop global country-specific inventories of land use flows. Using data from public databases, e.g. FAOSTAT, we developed methodologies for determining occupation and transformation flows for agricultural flows, forestry flows, urban flows and other land use flows such grassland and shrub land. Transformation flows were calculated by determining the differences between the same occupation flows across different years. The resulting inventory, representative for the year 2010, covers 19 occupation flows and 15 transformation flows for 226 countries and territories. With the exception of specific land use types, the coverage of available land occupation data per land class is above 98.8% at global scale. We illustrated the application of this inventory for LCIA purpose by calculating normalisation references for the ILCD recommended method developed by Mila i Canals et al. and by evaluating the most contributing land use classes and countries to the impacts. It highlighted the importance of urban land occupation and transformation, contributing to close to 50% of the impact altogether. For other tested LCIA methods (not addressed here), different distributions were observed, thus demonstrating a strong dependency on the limited number of land use types that typically drive the impacts and on the need to differentiate inventories into specific land use classes. The developed land use flow inventory is thus believed to be the most comprehensive, differentiated and up-to-date inventory available today, and its completeness is deemed sufficient to match ongoing developments in land use LCIA and help make large-scale footprint studies.