Consensus-based framework for the impact assessment of natural resource use in life cycle assessment: generalized impact pathways and recommended methods for abiotic resource use

Abstract Purpose This study aimed to establish a consistent framework for assessing the impacts of natural resource use within Life Cycle Assessment (LCA). As part of the outcomes of the UNEP Life Cycle Initiative’s GLAM Phase 3 Task Force on Natural Resources, the work defines the safeguard subject, generalized impact pathways applicable across all types of natural resources, and recommended methods for abiotic resource use that aligns with the developed assessment framework for natural resources. Methods An expert consensus was achieved through a structured evaluation of twenty existing methods using ten criteria, including relevance to the defined safeguard subject, consistency with impact pathways, data quality, and compatibility with Life Cycle Inventory (LCI) databases. The generalized impact pathways were developed to encompass abiotic, biotic and other renewable resources, integrating mechanisms such as dissipation, degradation, and occupation. Results The consensus-building process resulted in the definition of a common safeguard subject for natural resource use: the potential to make use of the instrumental values of natural resources. Generalized impact pathways were established to consistently describe cause-effect mechanisms across different categories of natural resources. The Future Welfare Loss (FWL) model was selected as the recommended approach for assessing mineral and fossil resource use. Characterization factors (CFs) were recalculated using updated 2018 commodity price data for 81 minerals, 3 fossil resources, and 2 energy carriers. The global annual impact of mineral and fossil resource use (using extraction flows as inputs) was estimated at approximately USD 3,483 billion, equivalent to about 4% of the 2018 global GDP. Conclusions While the generalized impact pathways are intended to be broadly applicable across natural resource categories, the operational recommendation and updated characterization factors currently focus on mineral and fossil resource use, whereas only interim recommendations could be identified for water resource use and land use assessment. Further methodological refinement is needed for renewable resources. Finally, we encourage LCI databases developers to improve the coverage of mineral and fossil resource dissipative flows in LCI databases to enhance the characterization of resource dissipation.