Global food production is a major driver of environmental impacts. Today's food system occupies 38% of the desert- and ice-free land, causes 26% of greenhouse gas (GHG) emissions, 32% of terrestrial acidification, 61% of freshwater withdrawals, and 78% of eutrophication. To keep environmental impacts within the planetary boundaries, drastic changes in food production and consumption are needed. The present study carried out a meta-analysis of 570 studies, with data from 119 countries. A harmonised database was derived for five environmental indicators: land use (land occupation), freshwater withdrawals (and scarcity-weighted freshwater withdrawals), global warming, acidification and eutrophication potentials. The data were standardised in several steps by: correcting differences in functional units, emission factors, characterisation factors, allocation methods, and system boundaries. Missing life cycle phases were filled by standard data. Emissions and environmental impacts were recalculated, whenever needed. The global totals were found to be consistent with global estimates. The meta-analysis of food LCA studies showed that large variability exists between producers of the same product, indicating substantial mitigation opportunities. The 90th percentile impacts were between 4-11x higher than the 10th percentile impacts for global warming, land use, acidification and eutrophication and even 5500x higher for scarcity-weighted water use. The impact distributions are highly skewed, with 25% of the producers causing about half of the environmental impacts. We found that different producers require different ways to reduce their impacts; no universal solutions exist. To define a mitigation strategy a detailed analysis of each production system in its context is therefore indispensable. Furthermore, trade-offs between different environmental impacts have to be taken into account. Consumers can mitigate environmental impacts by reducing their consumption of animal-based food and by avoiding producers with high environmental impacts, with synergies between these two strategies. To achieve these improvements, better information on the environmental impacts must be made available and communicated along the value chain.
