Shifting units, shifting views: how product mass and protein content influence environmental impact of Icelandic lamb

Abstract

Purpose Lamb meat is a crucial protein source in Icelanders’ diets. Extensive grazing lands, locally grown hay feed, and traditional farming methods are often used as arguments for Icelandic lamb meat’s environmental friendliness. However, no life cycle assessment (LCA) study exists to corroborate these arguments. This study conducts a national-level LCA to evaluate the environmental performance of lamb meat based on two functional units to identify key hotspot processes in its production. Method This study conducts a cradle-to-farm gate LCA at the national level for two functional units: 1 kg of edible lamb meat (ELM) and 100 g of ELM protein produced in Iceland in 2019. The multifunctionality between wool and meat is handled using mass allocation. The environmental impacts were estimated using the ReCiPe 2016 v1.1 mid-point (H) impact assessment method, emphasizing selected environmental categories: global warming, fossil resource scarcity, land use, and terrestrial ecotoxicity. In addition, the study conducts a scenario-based variability analysis by taking minimum and maximum values of inventory data to estimate the possible range of environmental impacts. Lastly, an overall uncertainty analysis and a global sensitivity analysis of the key hotspot process shed light on the variability and sensitivity of the LCA results. Result and discussion For the 18 ReCiPe impact categories, animal and feed (hay) production are the hotspot processes, followed by feed (grazing) as a hotspot for land use. The global warming impact for 1 kg of ELM ranges 41–53 kg CO2 equivalent, and for 100 g of protein, 19–29 kg CO2 equivalent. Fossil resource scarcity impact for 1 kg of ELM impact ranges 2.5–3.6 kg oil equivalent, and for 100 g protein, 1–2 kg oil equivalent. Terrestrial ecotoxicity impacts for 1 kg of ELM range 46–69 kg 1,4-DCB, and for 100 g protein, 21–37 kg 1,4-DCB. Lastly, land use impacts for 1 kg of ELM range 562–2448 m2a crop equivalent, and for 100 g protein, 261–1324 m2a crop equivalent. Conclusion With its traditional farming practices, Icelandic lamb meat production is close to an extensive farming system, which is in line with its higher global warming impact per kg ELM. Additionally, due to low hay yield and high fertilization rate, the impact on other impact categories is still higher compared to an extensive system. This perspective shifts when analyzed per 100 g of protein, where it performs close to the global average.