The carbon footprint of stone fruit production: Comparing process-based life cycle assessment and environmentally extended input-output analysis

Abstract

The development of sustainable products and practices must be supported by methodologies capable of evaluating their environmental performance in an objective and systematic manner. The most popular tool for carbon footprint (CF) assessment is arguably process-based life cycle assessment (pLCA). However, interest in tools such as environmentally extended input-output analysis (EEIOA) is growing rapidly due to the convenience of using economic-based inventories rather than material/energy-based ones. The objective of this investigation is to evaluate divergences between conventional pLCA and EEIOA in the analysis of CF using the production of stone fruits as a case study. The study uses a cradle to grave approach and it is based on a detailed economic, material and energy life cycle inventory of nectarines produced in Southeast Spain. The analyses yielded 1.07 kg CO2 eq./kg for the EEIOA and 0.899 kg CO2 eq./kg for the pLCA. This difference, which might sound acceptable, is due to the compensation of larger opposing discrepancies in the various stages and processes that make up the product life cycle. Thus, pLCA yielded significantly higher total CF emissions than EEIOA (0.23 EEIOA/pLCA ratio) in the upstream stage (agricultural and packaging processes). The opposite is observed in the core stage, where EEIOA carbon emissions were significantly higher than those calculated by pLCA (4.38 EEIOA/pLCA ratio). Differences in the downstream stage (mainly distribution and storage, and EoL phase) were less notable (1.40 EEIOA/pLCA ratio). Economic-based inputs, used in EEIOA (such as labour and service costs) and unaccounted for in pLCA, may be partly responsible for such divergences, while others should be linked to differences in the impact assessment procedures followed by each of these methodologies. These results raise some doubts about the potential of EEIOA and calls for further research on the validity, complementarity and the application domains of these methodologies. In any case, both modelling approaches agree in identifying the distribution and storage life cycle stages as main contributors to carbon emissions, calling for the implementation of measures to promote the consumption of seasonal and local fruit.