How prospective LCA handles time in circularity-oriented assessments: Evidence and gaps

Prospective life cycle assessment (pLCA) is increasingly used to support circular economy (CE) strategies, however how time is represented, across foreground interventions and evolving background systems, remains heterogeneous and often underreported, with implications for comparability and decision quality. This study reviews how CE-oriented pLCA operationalizes and conceptualizes time evolution and identifies recurring temporal design choices relevant for impact assessment practice. We conducted a systematic literature review (Scopus and Web of Science), identifying 121 eligible publications. We extracted (i) the circular loops and R-strategies addressed, (ii) operational time handling (background databases and models, foreground management approaches, scenarios and elements of change), (iii) conceptual framings of time (as resource, structure, and process). Results show that applications focus on material recovery and recirculation (83%), while slowing and intensifying strategies are rarely assessed (6%), narrowing is marginal (3%), and dematerializing/service substitution cases are absent. Across studies, foreground changes are often reported, but background modelling is frequently opaque: 70 out of 121 studies (58%) do not specify the background model, and many omit explicit time slices or scenario labels, limiting interpretability and cross-study comparison. Finally, four temporal design configurations are identified, combining weak or partial foreground–background coupling with snapshot or pathway-based temporal evolution. This study makes temporal considerations in circularity-oriented pLCA actionable by translating a fragmented literature into four recurring temporal design configurations and a decision rule with requirements for selecting and documenting them. We conclude with recommendations to improve transparency, and increase the decision relevance of pLCA.