An evaluation of life cycle assessment of European milk production.

Life cycle assessment (LCA) is a method regulated by ISO that conveys the environmental impact of products. LCA studies of the same product should be comparable to benefit environmental policy making. LCA of milk production has evaluated environmental issues such as greenhouse gas emissions, resource utilisation and land use change. Thirteen LCA studies of European milk production were analysed for comparability, and direct comparison was difficult due to technical issues, arbitrary choices and inconsistent assumptions. The strengths and weaknesses of LCA for evaluating an agricultural system are identified and improvements for comparability of future studies are also considered. Future LCA of milk production should ensure that: (1) the production system is appropriately characterized according to the goal of study; (2) a clear description of the system boundary and allocation procedures is provided according to ISO standards; (3) a common functional unit, probably Energy Corrected Milk, should be used or assumed fat and protein content presented to enable comparisons; (4) where appropriate, site-specific emission factors and characterization factors should be used in environmental hotspots (e.g. manure management, spreading of synthetic fertilizer, production of purchased feed), and phosphorous loss should be better addressed; (5) a range of impact categories including climate change, energy use, land use, acidification and eutrophication should be used to assess pollution swapping, all of which are subject to national or regional directives; perhaps in the future biodiversity should also be included; and (6) the sensitivity to choices of methods and uncertainty of final results should be evaluated.