UA could play a critical role in ensuring food security, closing the loop on urban resources, and reducing pressure on agricultural land in the forthcoming decades. The experiences of the SiEUGreen project addressed throughout this white paper were used to feature some of the most recent research on these themes. The learnings can be seen as a springboard for broader debate concerning the future of UA within a circular economy approach (Figure 3).

When considering UA, context matters. The type of technology used or business model pursued may need to be adapted according to the social/historical factors of the local setting. Different UA typologies benefit specific populations, which means that UA implementation will take on distinct forms in different countries and even in different cities within the same country. Therefore, it is important to promote local research and case study analysis that can highlight policy solutions to address context-related barriers and limitations. In SIEUGreen, this diversity was noted in the different showcases across the various geographical location of the case studies, which has contributed to the broad viewpoint of advantages and hindrances hampering UA and urban circularity described in this white paper. 

Another key takeaway is the importance of reconceptualising cities’ food provision role under the inspiration of circular and regenerative principles and practices. City food provision and UA systems can be designed considering circular economy regenerative cycles, with evidence pointing to the many advantages of closing the urban resource loop, but this is not a given. There are several components of the linear, take-make-disposal economy that are structurally in place, many of which reinforce systematic barriers and limitations (environmental, technological, economic, cultural/social) to achieving urban food provision through UA.

From an environmental perspective, UA suffers from a polarisation of opinions and results regarding its impacts on resource consumption and efficiency in closing the loop. The discrepancies around how well UA can contribute to biodiversity and climate change adaptation reveal the need for more evidence-based research, clear monitoring tools, and evaluation/assessment of the different UA typologies and their impact on the environment.

As new (circular enabling) technologies and UA innovation and business model potential drive the development of UA activities, these are other building blocks that need to be addressed in this discussion. Innovative technological developments are enablers that can support and promote UA activities in all R´s, from water reduction consumption enabled by aquaponic technology; to composting techniques to reuse organic household waste as organic fertiliser reducing waste disposal in landfills; and especially on recycling and recovering of materials and energy from the urban waste sector (e.g. Anaerobic Digestion). Nevertheless, implementing these solutions requires more experimentation, large-scale tests and validation both concerning their efficiency, positive environmental impacts, as well as economic viability. There are also several regulatory challenges concerning waste and waste management that need to be addressed, as well as social acceptance and awareness concerning the value of “waste”. 

On the economic side, high investment costs for some agricultural technologies and difficulties accessing financial support limit UA implementation. Other obstacles are related to competitive prices of food produced in larger supply chains and the underdevelopment of a business case for circular resource models. Lastly, there is limited recognition of the positive and indirect economic impacts of UA’s social and environmental benefits. To address these challenges, researchers in relevant fields could construct a holistic cost-benefit analysis of these impacts to test the economic soundness of UA. Without such tools, public authorities may continue to neglect the broader economic impact that UA might offer through its social benefits, namely on health, boosting the local economy, enabling social inclusion, and alleviating poverty.

Even when the direct economic potential is limited, UA has the potential to trigger valuable gains. Empowering groups at risk of social exclusion, lessening poverty, ameliorating human health and well-being, and improving environmental education—all of these are side effects commonly reported of UA. While technological progress, innovation, and developing a business case for UA are all important, the deep societal impact these activities can offer should not go unnoticed. Several other societal benefits can be stressed as potential gains in the transition to a circular economy. However, it is also important to note that behaviour and cultural barriers have a deep impact when fostering a closed-loop approach to UA (especially concerning overcoming prejudice against waste as a resource).

Existing research, as well as the SiEUGreen showcases, point towards the central role of local governance and public policy in fostering closed loops in cities through various mechanisms (e.g., financial incentives, regulations) that support and promote UA as a pathway to address urban challenges. One of the main challenges is the need to overcome the siloed development of planning policies and, instead, enable collaborations within the urban innovation ecosystem to foster cities’ sustainable future development. The transition to a circular urban agriculture needs structural change and the establishment of framing conditions that governments, both at local and national levels, can encourage. This can include the development of tools to monitor environmental impacts, a sound regulatory framework, knowledge exchange and demystification of circular economy processes, collaboration among urban and regional actors, and showcasing successful examples that can lend themselves to the development of a business case for UA.

The different SiEUGreen showcase examples allowed for interesting viewpoints on UA activities and pointed to several important questions that need to be addressed. What seems certain is that cities play a fundamental role (both positive and negative) in leading the global transition towards more sustainable food production, consumption, and waste systems. As this role will only increase in forthcoming years, it is important to foster discussions and stimulate debates on how to re-conceptualise urban food provision through the lens of a circular economy.

 Table 1: Summary of drivers and barriers