Agriculture is a major sector responsible for greenhouse gas emissions. Local food production can contribute to reducing transport-related emissions. Since most of the worldwide population lives in cities, locally producing food implies practicing agriculture in urban and peri-urban areas. Exemplary, we analyze the potential to produce fresh vegetables within Berlin, Germany. We investigate the spatial extent of five different urban spaces for soil-based agriculture or gardening, i.e., non-built residential areas, allotment gardens, rooftops, supermarket parking lots, and cemeteries. We also quantify inputs required for such food production in terms of water, human resources, and investment. Our findings highlight that up to 82% of Berlin’s vegetable demand could be produced within the city, based on a reasonable validation of existing areas. Meeting this potential requires 42 km2 of urban spaces for cultivation, a considerable amount of irrigation water, around 17 thousand gardeners, and over 750 million EUR of initial investments. The final vegetable cost would be around 2 EUR to 10 EUR per kg without any profit margin. We conclude that it is realistic to produce a significant amount of Berlin's vegetable demand within the city, even if it comes with great challenges.
The article introduces and exemplifies the approach of evidence-based narratives (EBN). The methodology is a product of co-design between policy-making and science, generating robust intelligence for evidence-based policy-making in the Directorate General for Research and Innovation of the European Commission (DG RTD) under the condition of high uncertainty and fragmented evidence. The EBN transdisciplinary approach tackles practical problems of future-oriented policy-making, in this case in the area of programming for research and innovation addressing the Grand Societal Challenge related to climate change and natural resources. Between 2013 and 2018, the EU-funded RECREATE project developed 20 EBNs in a co-development process between scientists and policy-makers. All EBNs are supported with evidence about the underlying innovation system applying the technological innovation systems (TIS) framework. Each TIS analysis features the innovation, its current state of market diffusion and a description of the innovation investment case. Indicators include potential future market sizes, effects on employment and environmental and social benefits. Based on the innovation and TIS function analyses, the EBNs offer policy recommendations. The article ends with a critical discussion of the EBN approach.