A critical perspective on uncertainty appraisal and sensitivity analysis in life cycle assessment

In this study, we review approaches for uncertainty appraisal in the life cycle assessment literature. We cover the acknowledgment of stochastic and epistemic uncertainty in uncertainty and sensitivity analysis and knowledge quality assessment, respectively. Consistent with previous works, our findings indicate that uncertainty is only appraised in a few studies on life cycle assessment. Most of these contributions cover only one of the phases of life cycle assessment, mainly the life cycle inventory phase. Less attention has been devoted to the phases of goal and scope definition and life cycle impact assessment. Additionally, in most studies, uncertainty analysis and sensitivity analysis have been applied independently, as it is wrongly assumed they cover different uncertainty spaces. We also identify the scope for improvement in the appraisal of epistemic uncertainty and the correct definition of the probability distribution of the uncertain factors. We conclude by highlighting studies in which sensible practices have been adopted, identifying open challenges, and suggesting possible ways forward.