Comparative Life Cycle Assessment of alternative winter salad value chains supplying the United Kingdom

Lettuce is an established food commodity in the UK increasingly facing supply challenges in winter due to adverse weather events and rising energy costs. We investigate whether an agroecologically grown salad mix of lettuce and underutilised leafy greens produced in the Azores, Portugal, could be part of a sustainable solution. We performed a Life Cycle Assessment to compare the environmental impacts of this salad mix with four other value chains for winter salad supply to the UK: conventional open-field lettuce production chains in Spain using (1) current irrigation practices; (2) 100 % desalinated irrigation water; or hydroponic controlled environment agriculture within the UK powered by (3) the national electricity mix; (4) 100 % wind-generated electricity. Results indicated that the leafy-greens agroecological value chain incurred the smallest environmental burdens across 7 to 11 of 16 impact categories studied. Substituting Spanish winter salad supply with agroecological leafy green production in the Azores, if well managed, could reduce many environmental burdens whilst diversifying leafy greens intake. Nevertheless, all winter value chains were associated with larger environmental burdens than conventional open-field production of lettuce in the UK summer, pointing to the importance of seasonal consumption and wider adoption of agroecological techniques to effectively reduce environmental impact.