The price of protein: Review of land use and carbon footprints from life cycle assessments of animal food products and their substitutes

Animal husbandry, aquaculture and fishery have major impacts on the environment. In order to identify the range of impacts and the most important factors thereof, as well as to identify what are the main causes of the differences between products, we analysed 52 life cycle assessment studies (LCAs) of animal and vegetal sources of protein. Our analysis was focused only on land requirement and carbon footprints.In a general conclusion it can be said that the carbon footprint of the most climate-friendly protein sources is up to 100 times smaller than those of the most climate-unfriendly. The differences between footprints of the various products were found mainly to be due to differences in production systems. The outcomes for pork and poultry show much more homogeneity than for beef and seafood. This is largely because both beef and seafood production show a wide variety of production systems.Land use (occupation), comprising both arable land and grasslands, also varies strongly, ranging from negligible for seafood to up to 2100 m2 y kg−1 of protein from extensive cattle farming. From farm to fork the feed production and animal husbandry are by far the most important contributors to the environmental impacts.

► 104 Carbon footprints and 43 land footprints of protein sources are examined. ► Very large differences in impact between protein sources were found. ► In the life cycles, in general, the farm phase is the most important. ► Vegetal sources, poultry products and certain seafood have low carbon footprints. ► Ruminant meat and some types of seafood have high carbon footprints.