PurposeThe purpose of this paper is to empirically identify key factors of UK food supply chains (SCs) that significantly contribute to CO2 emissions (CO2e) taking into account the life cycle assessment (LCA). The UK food supply chain includes imports from other countries.Design/methodology/approachThis research develops a conceptual framework from extant literature. Secondary data obtained from ONS and FAOSTAT covering from 1990 to 2014 are analysed using Multilinear Regression (MLR) and Stochastic Frontier Analysis (SFA) to identify the factors relating to CO2 emissions significance, and the efficient contributions that are being made to their reduction in the UK food supply chains.FindingsThe study results suggest that Transportation and Sales/Distribution are the two key factors of CO2 emissions in UK food supply chains. This is confirmed by two multivariate methods, MLR and SFA. MLR results show that transportation increases UK CO2 emissions by 10 tonnes of CO2 emissions from one tonne of fruits and vegetables imports from overseas to the UK Sales and Distribution reduces the UK CO2 emissions by 1.3 tonnes of CO2 emissions due to improved, technological operation activities in the UK. In addition, the SFA results confirm that the key factors are sufficient to predict an increase or decrease in CO2 emissions in the UK food supply chains.Research limitations/implicationsThis study has focused on the LCA of the UK food supply chain from limited data. Future studies should consider Sustainability Impact Assessment of the UK food supply chain, identifying the social, economic, regulatory and environmental impacts of the food supply chain using a re-defined LCA (all-inclusive assessment) tool.Practical implicationsThis research suggests that food supply chain professionals should improve efficiency, e.g. the use of solar energy and biogas, and also integrate low-carbon policies and practices in food supply chain operations. Furthermore, governments should encourage policies such as mobility management programmes, urban redevelopment and privatisation to enhance better transportation systems and infrastructure to continuously reduce CO2e from the food trade.Originality/valueAlthough logistics play a major role in CO2 emissions, all logistics CO2 emissions for other countries are not included in the ONS data. This research reveals some important insights into the UK food supply chains. Logistics and other food supply chain processes of importing countries significantly contribute to CO2 emissions which are yet to be considered in the UK food SCs.