Environmental impacts of combined milk and meat production in Norway according to a life cycle assessment with expanded system boundaries

The environmental burdens from combined milk and meat production in Norway have been studied. A model of three typical farms was constructed to represent the three most important regions for dairy production in Norway (central, central southeast and southwest). Processes from cradle to farm gate were covered in the assessment, including all activities on the farm, along with the production of machinery, equipment, buildings, diesel, oil, fertilizer, lime, seeds, pesticides, detergents, plastic, silage additive, medicines and related transport. The results were given for the impact categories global warming potential (GWP), fossil depletion, freshwater ecotoxicity, freshwater eutrophication, human toxicity, marine ecotoxicity, marine eutrophication, ozone depletion, agricultural land occupation, photochemical oxidant formation, terrestrial acidification and terrestrial ecotoxicity. To document the impact and to be able to compare the findings to results from previous studies, processes often excluded in literature were individually omitted from the assessment. The consequences of using alternative literature values for selected subprocesses were calculated and the sensitivity of the results to different parameter settings was evaluated by varying the parameter values 750% of the default value. GWP impacts of 1.5–1.6 kg CO 2-eq per kg energy corrected milk (ECM) and 17.7– 18.4 kg CO2-eq per kg carcass were calculated. By excluding production of machinery, buildings, medicines, detergents, seeds, fence and pesticides, the GWP impacts were reduced by approximately 8% per kg carcass and 9% per kg ECM. Compared to results from other studies, the GWP related to production of milk and meat was high in the present investigation. The validity of comparisons with other studies is however low due to differences in allocation and system boundaries.