Food-System Life Cycle Assessment

Food-system life cycle assessment (LCA) quantifies the environmental footprint of a food, meal or diet across its entire life cycle — from agricultural inputs on the farm, through processing, packaging, transport, retail and cooking, to waste disposal. Following the ISO 14040/14044 framework, an analyst defines a functional unit (such as one kilogram of food, 100 grams of protein, or 1000 kilocalories), compiles a life-cycle inventory of all inputs and emissions at each stage, characterises those flows into impact indicators (greenhouse-gas emissions, land and water use, eutrophication and acidification), and interprets the result with sensitivity and uncertainty analysis. Poore and Nemecek's 2018 Science synthesis, covering tens of thousands of farms worldwide, showed that impacts vary as much as fifty-fold among producers of the same product and that even the lowest-impact animal foods typically exceed plant substitutes — establishing LCA as the central tool for comparing the sustainability of foods and diets.