The carbon footprint of fruits: A systematic review from a life cycle perspective

The agrifood system's challenge of meeting an ever-increasing demand for food while at the same time minimizing its carbon impact is reflected in increased research on the carbon footprint assessment of agrifood products. Despite fruits representing a significant and expanding proportion of total agrifood production, not only is their whole-of-life carbon footprint inadequately explored, but also the existing knowledge in this area is fragmented and dispersed. To address these issues, this study systematically reviewed 161 peer-reviewed journal articles using the Preferred Reporting Items for Systematic Literature Reviews and Meta-Analyses framework. The review focused on the scope of each study, assessment methods, emission hotspots, and greenhouse gas mitigation strategies, alongside a meta-analysis of 289 carbon footprint values, establishing reference points for fruits' carbon footprint. Findings revealed that existing studies predominantly focused on cradle-to-farm gate spatial boundaries and single-year production data. Process-based life cycle assessment adhering to the International Organization for Standardization (ISO) 14040 and 14044 standards was the dominant methodology. The production stage was identified as the greenhouse gas emission hotspot in the majority of studies, however, a meta-analysis of carbon footprint values across the entire fruit life cycle showed that the production stage is a critical but not the sole hotspot. The meta-analysis suggests an average cradle-to-farm gate carbon footprint of 0.503 ± 0.365 kg carbon dioxide equivalent (CO₂eq) per kg fruit. Expanding the boundary to cradle-to-retail and cradle-to-grave resulted in mean values of 0.743 ± 0.193 and 1.257 ± 0.886 kg CO₂eq per kg fruit, respectively. Emphasizing the importance of incorporating carbon sequestration in future studies for accurately positioning fruits among agri-food products in terms of their carbon footprint, the study underscores the need for developing a standard protocol for more reliable and comparable estimates. Findings and strategies for reducing emissions contribute to ensuring sustainable fruit production, with both academic and practical implications.