Demand side options to reduce greenhouse gas emissions and the land footprint of urban food systems: A scenario analysis for the City of Vienna

The provision of food is fundamental for society, but it is also a major driver of environmental change. Cities are important consumers of food, harboring more than half of the global population, a share that is expected to grow in the coming decades. Here we investigate the urban food system of Vienna, a large central European city. We quantify the land and greenhouse gas (GHG) footprint of Vienna's food system and explore potentials to reduce the urban footprint through changes in food consumption, applying a counterfactual approach. We systematically compare the land and GHG effect of a shift of consumption towards i) diets with a lower share of animal products, ii) food from regional agriculture and iii) food from organic agriculture, based on the FoodClim model presented in this study. Our results show that Vienna's food system currently requires 639000 ha of agricultural land, about two thirds of it in foreign countries and emits 2.29 Mt CO2e/yr over the whole supply chain. A change in diets has the largest impact, reducing both Vienna's food system land footprint by 54% and its GHG footprint by 57%, while the effect of regionalization is comparatively small. Combined scenarios show that it is possible to maintain a healthy level of meat in diets and to switch to organic agriculture with lower land and livestock productivities and to still save half of the GHG emissions, while avoiding an expansion of the land footprint.