Cities as carbon pools: Three territorial scenarios for soil-regenerative urbanism

Abstract

Focusing on Swiss metropolitan areas, this article addresses the resistance and resilience of cities against climate change and other environmental crises. The aim is to connect new knowledge on soil-based ecosystem services, particularly carbon sequestration and its multiple co-benefits, with sustainable urban planning, design, and maintenance practices. In this regard, urban regeneration operations are considered significant opportunities. To connect new knowledge about soil-based ecosystem services and carbon sequestration with sustainable decision-making in urban regeneration, this article mobilizes a mixed methodology. First, the main results of an interdisciplinary field survey recently conducted in Lausanne and Zurich are presented, followed by a research-by-design exploration. A series of principles for soil regenerative urbanism is established to (1) preserve existing functional soils, and therefore the stock of organic carbon they contain; (2) regenerate soils on currently artificialized surfaces, and therefore constitute new stocks of organic carbon from the circular management of mineral and organic wastes; (3) improve and diversify the vegetation cover and related maintenance practices of both preserved and regenerated soils, and therefore enable them to gradually sequestrate more organic carbon in the future. Ultimately, three strategic urban regeneration scenarios are proposed to enhance soil carbon sequestration. Each of them relates to a specific dimension of cities understood as ecosystems: (1) urban morphology, soil preservation, and desealing in open spaces; (2) urban metabolism, circular management of waste to recreate soils; (3) urban biotopes, vegetation, and care practices to diversify ecological habitats.