Why circular economics and nature-based solutions need each other in cities
Independent from one another, the sustainability concepts of circular economics and nature-based solutions have gained traction in recent years as promising solutions to the increasingly unsustainable state of affairs in our cities. Circular economy is a new model for addressing human needs, while fairly distributing resources without undermining the functioning of the biosphere or crossing planetary boundaries (the latter as defined by Johan Rockström in 2009). A large focus within the circular economy is the proper management of materials and the use of natural resources in closed loop cycles, similarly to natural systems, where water and nutrients are continuously cycled for the functioning of our ecosystems.
The term, nature-based solutions (NbS), was first put forward by the International Union for the Conservation of Nature (IUCN) and the European Commission during the later part of the past decade. The term is relatively new and is still being framed after having seen various successive definitions. All definitions agree on the constituting aspects to be (i) the application of biological designs or processes for engineering or invention (biomimicry) and (ii) the interconnection of natural areas that conserve natural ecosystem functions (green infrastructure). IUCN defines NbS as actions which are inspired by, supported by or copied from nature to help societies address a variety of environmental, social and economic challenges in sustainable ways (Cohen-Shacham et al., 2016). NbS are energy- and resource-efficient and resilient to disruption but must be adapted to local conditions to be successful (European Commission, 2015). For both circular economics and NbS, there is no accepted organisation with the undisputed authority to define what either mean exactly.
However, successful case studies are becoming increasingly common, which have generated awareness and momentum for circular economics and NbS to become implemented at larger scales and more mainstreamed in national policies and international programmes.
In our global ecosystem, both circular economics and NbS can have a big impact in cities. Cities occupy only three percent of the Earth’s surface area but house more than half of the world’s population, consume over 75% of the global resources and are responsible for 60-80% of the greenhouse gases. Environmental challenges and urbanisation opportunities are inherently correlated. Cities are the principal engine for economic growth and transforming the built environment will lead the way towards a circular economy. In the same node, NbS can save energy, conserve water, reduce infrastructure costs, boost important biodiversity, and increase the health and wellbeing of citizens. Strategies and interventions based on the principles of circular economics and NbS can yield ecological benefits, encourage conscious behaviour by citizens, and contribute to the protection of the environment.
Across the world, cities have substantial issues to overcome. Some of the most pressing include the effect of climate change, degraded water systems, car-centric transportation networks, unsustainable agricultural practices, and a lack of resilient systems. Slowly, cities and their stakeholders are beginning to appreciate the promise of NbS. A circular economy based on NbS has the potential to be the game changer for the transformation of cities. The next research challenge is the proper value quantification of the different NbS solutions under actual real world circumstances. Cost and benefits, direct and indirect, require systematic calculation, measurement and monitoring over time. If we can answer these critical questions, and uncover which NbS are truly valuable and effective, NbS will prove to be the vehicle to realise a circular economy in our cities.
 Cohen-Shacham, E., Walters, G., Janzen, C., & Maginnis, S. (2016). Nature-based solutions to address global societal challenges. IUCN, Gland.
 European Commission. (2015). Towards an EU research and innovation policy agenda for nature-based solutions and re-naturing cities. Final Report of the Horizon 2020 expert group on “Nature-Based Solutions and Re-Naturing Cities.” European Commission, Brussels, Belgium.
My PhD research (University College Dublin; Trinity College Dublin) hopes to answer some of these questions by mapping the life-cycle impacts and effectiveness of various nature-based solutions and their place in the circular cities of the future. Interested? Read more here.
If you are working in the field of nature-based solutions or circular cities, and/or have opinions on this subject, I would love to hear from you and potentially interview you. Please contact me and I will get back to you as soon as possible. Thank you.