Assessing the potential to scale-up urban agriculture in the Global North

Urban agriculture (UA) is frequently promoted as a pathway to improve urban sustainability, food security, and resilience, yet cross-city evidence on its scalable, system-wide impacts remains limited and methodologically inconsistent. We assess the theoretical scaling potential and food–energy–water (FEW) metabolism implications of expanding low-tech UA across five Global North cities—London, New York City, Paris, Dortmund, and Gorzów Wielkopolski—using a harmonized two-part framework. First, we conduct 1-m resolution spatial multi-criteria suitability modeling, supplemented with sensitivity scenarios. Second, we upscale empirically derived site-level resource–yield “metabolisms” to quantify potential contributions to vegetable provisioning, resource demand, and nutrient cycling. Across base scenarios, 12–24% of city area is suitable for UA, with individual/home gardens comprising the dominant share of expandable space in every case. Under average observed yields, scaled UA could supply 16–95% of current non-tropical vegetable demand (and substantially more under high-productivity assumptions), while requiring relatively modest shares of city electricity use but potentially meaningful shares of potable water in smaller cities. Expanded UA could also absorb more than 100% of current vegetable food-waste streams via composting, indicating strong circularity leverage. However, participation requirements emerge as a primary constraint: labor availability and willingness limits feasible realization of these theoretical maxima. Together, results provide a transferable, cross-city methodology and identify policy-relevant leverage points—especially enabling home gardening, securing land tenure, supporting new farmers or gardeners, and pairing expansion with composting and water-harvesting practices—to design context-sensitive UA scaling strategies.