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Climate change, natural disasters and social unrest constantly threaten the role of the food system in ensuring adequate access to nutritious food for the population. Resilience is therefore emphasised in the food system in order to continue to function despite disruptions. However, due to the complex nature of the food system, multiple risks are easily transferred from one activity to another, which also exacerbates existing power imbalances between food system actors. Misaligned interests between actors and the food system make it difficult for governance to achieve intended effects, while efforts at the actor level do not necessarily lead to resilient systemic outcomes. Therefore, this thesis explores potential conflicts and coordination between the actor level and food system resilience through theoretical and empirical research in three interrelated papers and a discussion chapter. Paper 1 presents a literature review, aiming to answer the question of which actors contribute to food system resilience and how their efforts contribute to resilience during disruptions. The paper also summarises the supportive roles that help actors to affect the food system, and the underlying mechanisms that enable these actors to exert their influence. Paper 2 examines the resilience of restaurant organisations in Wuhan during the COVID-19 pandemic and explores the implications of organisational resilience for achieving sectoral and food system resilience. Paper 3 examines the effects of governance on the Chinese pork system and the trade-offs between resilience, sustainability and various internal dimensions of resilience, e.g. robustness, recovery and reorientation. Building on three preceding papers, the discussion chapter investigates the challenges of governance for food system resilience and explores strategies for enhancing resilience. Taken together, three papers and one discussion chapter provide insights into the overarching theme of the Ph.D. and offer theoretical and

Food system resilience has multiple dimensions. We draw on food system and resilience concepts and review resilience framings of different communities. We present four questions to frame food system resilience (Resilience of what? Resilience to what? Resilience from whose perspective? Resilience for how long?) and three approaches to enhancing resilience (robustness, recovery, and reorientation—the three “Rs”). We focus on enhancing resilience of food system outcomes and argue this will require food system actors adapting their activities, noting that activities do not change spontaneously but in response to a change in drivers: an opportunity or a threat. However, operationalizing resilience enhancement involves normative choices and will result in decisions having to be negotiated about trade-offs among food system outcomes for different stakeholders. New approaches to including different food system actors’ perceptions and goals are needed to build food systems that are better positioned to address challenges of the future. Expected final online publication date for the Annual Review of Environment and Resources, Volume 47 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Urban agriculture can contribute to food security, food system resilience and sustainability at the city level. While studies have examined urban agricultural productivity, we lack systemic knowledge of how agricultural productivity of urban systems compares to conventional agriculture and how productivity varies for different urban spaces (e.g., allotments vs. rooftops vs. indoor farming) and growing systems (e.g., hydroponics vs. soil‐based agriculture). Here, we present a global meta‐analysis that seeks to quantify crop yields of urban agriculture for a broad range of crops and explore differences in yields for distinct urban spaces and growing systems. We found 200 studies reporting urban crop yields, from which 2,062 observations were extracted. Lettuces and chicories were the most studied urban grown crops. We observed high agronomic suitability of urban areas, with urban agricultural yields on par with or greater than global average conventional agricultural yields. “Cucumbers and gherkins” was the category of crops for which differences in yields between urban and conventional agriculture were the greatest (17 kg m−2 cycle−1 vs. 3.8 kg m−2 cycle−1). Some urban spaces and growing systems also had a significant effect on specific crop yields (e.g., tomato yields in hydroponic systems were significantly greater than tomato yields in soil‐based systems). This analysis provides a more robust, globally relevant evidence base on the productivity of urban agriculture that can be used in future research and practice relating to urban agriculture, especially in scaling‐up studies aiming to estimate the self‐sufficiency of cities and towns and their potential to meet local food demand.

As urban areas and land-use constraints grow, there is increasing interest in utilizing urban spaces for food production. Several studies have uncovered significant potential for urban growing to supplement production of fruit and vegetables, focusing on one or two cities as case studies, whilst others have assessed the global scale potential. Here, we provide a national-scale analysis of the horticultural production potential of urban green spaces, which is a relevant scale for agri-food and urban development policy making using Great Britain (GB) as a case study. Urban green spaces available for horticultural production across GB are identified and potential yields quantified based on three production options. The distribution of urban green spaces within 26 urban towns and cities across GB are then examined to understand the productive potential compared to their total extent and populations. Urban green spaces in GB, at their upper limit, have the capacity to support production that is 8× greater than current domestic production of fruit and vegetables. This amounts to 38% of current domestic production and imports combined, or >400% if exotic fruits and vegetables less suited to GB growing conditions are excluded. Most urban green spaces nationally are found to fall within a small number of categories, with private residential gardens and amenity spaces making up the majority of space. By examining towns and cities across GB in further detail, we find that the area of green space does not vary greatly between urban conurbations of different sizes, and all are found to have substantial potential to meet the dietary needs of the local urban population. This study highlights that national policies can be suitably developed to support urban agriculture and that making use of urban green spaces for food production could help to enhance the resilience of the national-scale food system to shocks in import pathways, or disruptions to domestic production and distributio

In recent decades, large-scale deployment of photovoltaic (PV) power leads to management challenges for recycling PV module waste in China. With the growth of waste PV volumes, it is necessary to figure out the spatio-temporal distribution of PV waste at the provincial level. Based on China’s carbon neutrality goal by 2060, six development pathways of PV installed capacity are proposed to identify in-use stocks of PV capacity. In particular, we develop the retired flow estimation model for PV modules that is constructed by three PV module degradation scenarios. The results show that a relatively large scale of PV waste will be started to emerge in China by 2030 and the cumulative waste is expected to reach 1100∼ 1450 GW by 2060. Our findings also indicate an unequal distribution of PV waste across regions and the highest PV waste volumes by 2060 is the East China region at 31.4%, with Shandong (8.99%) and Hebei(8.65%) ranking as the top provinces. This prospective research will help the PV industry plan the location and capacity of recovery facilities at an appropriate time to advance toward a more resource efficient and circular economy.

Sustainably ensuring food security and safety for the urban population is a major challenge. In this perspective, we present the concept of ‘rurbanisation’ (the ruralisation of urban areas through increased urban agriculture) as a holistic strategy to provide a resilient food system. In particular, we focus on the postharvest benefits of urban agriculture for environmentally sustainable food supply chains, enhanced nutritional content of fresh produce and access to fresh, local and seasonal food. However, upscaling current urban agricultural systems requires improvement in current technologies and local infrastructure as well as the transfer of knowledge and skills to new urban farmers. This perspective summarises the main challenges that urban agriculture is currently facing from a postharvest quality and safety point of view, and highlights the research gaps and opportunities for improvements in that area.

Sustainably ensuring food security and safety for the urban population is a major challenge. In this perspective, we present the concept of ‘rurbanisation’ (the ruralisation of urban areas through increased urban agriculture) as a holistic strategy to provide a resilient food system. In particular, we focus on the postharvest benefits of urban agriculture for environmentally sustainable food supply chains, enhanced nutritional content of fresh produce and access to fresh, local and seasonal food. However, upscaling current urban agricultural systems requires improvement in current technologies and local infrastructure as well as the transfer of knowledge and skills to new urban farmers. This perspective summarises the main challenges that urban agriculture is currently facing from a postharvest quality and safety point of view, and highlights the research gaps and opportunities for improvements in that area.

500,000 tonnes of waste electrical and electronic equipment (WEEE) is collected and treated in the authorised WEEE system in the UK annually. Greenhouse gas emissions result from the transportation and treatment processes, but emissions reductions occur elsewhere in the economy when secondary materials, reused EEE and recovered electricity substitute virgin materials. Here we investigate the carbon footprint of the authorised WEEE system in the UK, utilising a combined material flow analysis (MFA) and life cycle assessment (LCA). The potential for improvements in the carbon footprint are investigated through optimisation of logistics by solving a Vehicle Routing Problem with the objective of minimising carbon footprint. Detailed primary data was obtained from a producer compliance scheme and the collection and pre- treatment operators, yielding highly specific emissions and material flow data across these stages. Data covering the recycling, incineration and landfill stages was sourced from the Ecoinvent 3.7 database. The LCA results show a net carbon footprint benefit for the collection and treatment across all WEEE streams. The average carbon footprint per tonne of WEEE was -2.01tCO2eq., consisting of 0.903tCO2eq. of gross emissions and -2.92tCO2eq. of avoided emissions. The gross emissions are mainly from recycling and energy-from-waste, and the avoided emissions from the substitution of 0.748t of virgin material with recycled material. Furthermore, optimisation of AATF allocation achieved a further improvement of 0.22tCO2eq. per tonne of WEEE by increasing use of AATFs with higher recovery rates. Specific findings include the large range in total emissions when WEEE is sent to different pre- treatment plants, and the finding that energy-from-waste is less beneficial than landfill from a carbon footprint perspective. Implications include informing decision making at the industry and policy level to improve the carbon footprint of the WEEE system and increasing pu