Towards a Cross-Sectoral View of Nature-Based Solutions for Enabling Circular Cities

Abstract

A framework developed by the COST Action Circular City (an EU-funded network of 500+ scientists from 40+ countries; COST = Cooperation in Science and Technology) for addressing Urban Circularity Challenges (UCCs) with nature-based solutions (NBSs) was analyzed by various urban sectors which refer to different fields of activities for circular management of resources in cities (i.e., reducing use of resources and production of waste). The urban sectors comprise the built environment, urban water management, resource recovery, and urban farming. We present main findings from sector analyses, discuss different sector perspectives, and show ways to overcome these differences. The results reveal the potential of NBSs to address multiple sectors, as well as multiple UCCs. While water has been identified as a key element when using NBSs in the urban environment, most NBSs are interconnected and also present secondary benefits for other resources. Using representative examples, we discuss how a holistic and systemic approach could facilitate the circular use of resources in cities. Currently, there is often a disciplinary focus on one resource when applying NBSs. The full potential of NBSs to address multifunctionality is, thus, usually not fully accounted for. On the basis of our results, we conclude that experts from various disciplines can engage in a cross-sectoral exchange and identify the full potential of NBSs to recover resources in circular cities and provide secondary benefits to improve the livelihood for locals. This is an important first step toward the full multifunctionality potential enabling of NBSs.

Nature-Based Solutions for Agriculture in Circular Cities: Challenges, Gaps, and Opportunities

“…Introducing circular processes into the city offers opportunity to increase sustainability, and in this respect, Atanasova et al [5] formulated a set of urban circularity challenges (UCC) [6,7]. Closing of the key cycles (i.e., water, nutrients, materials .…”

“…. ) as much as possible [5][6][7]9] optimizes the utilization of urban resources [14,15]. Addressing the UCC 3 on "Nutrient recovery and reuse" [5] comprises areas of great concern in UA, e.g., nutrient streams-especially when phosphorous (P) is involved.…”

“…If implemented to a high standard, UA can respond to several of the UCC [5][6][7], and it will cover a range of scales-from small scale, such as domestic food growing [17], to large scale, such as in peri-urban farming. Urban agriculture addresses primarily the UCC 5 of "Food and biomass production"; however, it touches on most other UCC as well [5][6][7]. Its primary production sites are located within the city boundaries or in transitional urban hinterland zones.…”

“…Urban agriculture also requires a joint adaptation of other UCC within the urbanrural nexus, such as nutrient recovery and reuse (UCC 3 ), urban water management and treatment (UCC 1,2 ), and improved energy efficiency (UCC 6 ) [5][6][7]. The geographical locations, complex networks, and individual characteristics of each UA project-including its input (I) and output (O) resources-are of great importance for the project's success.…”

“…In the face of growing concerns about resource constraints and the need to act on the global climate emergency, many countries intend to move towards a greener, competitive, and "resourceful" urban circular economy (CE) [1][2][3]. Food and biomass production can significantly contribute to closing of material cycling, thus maximizing the reuse of resources in the urban environment itself while reducing the need for external resource inputs (I) [4][5][6][7]. The primary production of food and biomass within the city has environmental, social, and economic benefits depending on how the nature-based solutions (NBS) are implemented.…”