Climate and biodiversity impact of beef and lamb production - A case study in Sweden

CONTEXT: The climate impact of meat production is a hotly debated topic. What is less often highlighted is that grazing ruminants can have positive impacts on biodiversity. OBJECTIVE: The aim of this study was to use a life cycle perspective to assess both the climate and biodiversity impact of different beef and lamb production systems in Sweden. METHODS: Applying a life cycle perspective, a quantitative method to assess biodiversity was used, with a scoring system based on land use. For the climate impact calculations, the ClimAg biophysical systems model was used, including emissions from drained organic soils and carbon sequestration in mineral soils. The functional unit was 1 kg carcass weight. RESULTS AND CONCLUSIONS: The results indicated large differences in biodiversity and climate impact between the production systems studied. Dairy bulls had relative low emissions of greenhouse gases, but also a low biodiversity score (a high score indicates higher level of biodiversity). Beef breed steers and heifers had higher emissions of greenhouse gases but a higher biodiversity score, suggesting a trade-off between climate and biodiversity impact. Also for lamb meat, greenhouse gas emissions vary among production systems. A system with winter born lambs slaughtered in spring, closely followed by spring born lambs slaughtered in autumn, had the lowest emissions, while spring born lambs slaughtered in winter had the highest emissions. Winter lambs on the other hand, had a relatively high biodiversity score, due to a long rearing period and an extensive land use with a high proportion of semi-natural grasslands. Climate impact was in all systems related to methane from enteric fermentation, emissions from manure storage, and emissions from organic soils. With the assumptions made in this study, soil carbon sequestration is suggested to reduce the climate impact by 5-7% of the total emissions. Biodiversity impact was in all systems positively related to the amount of grazing in permanent grasslands, in particular semi-natural grasslands. Because seminatural grasslands are among the most species rich terrestrial ecosystems in Europe, a large surface area grazed resulted in high biodiversity scores in the present model. SIGNIFICANCE: This study used a novel approach for biodiversity assessment, where the positive contribution of semi-natural grasslands to biodiversity was quantified and put in relation to the modelled climate impact.