Today, humanity enjoys the benefits of the economic growth of the last decades. While the global poverty rate is reduced, we are facing the existential threat of climate change. The linear economic model is the main cause for the evolving climate crisis that may have irreversible effects on humans, the built environment, and the biosphere; recent studies demonstrate that over 3.3 billion people live in places that are highly vulnerable to climate change, while the global and regional water cycle is changing, and water variability is increasing.
The circular economy is designed to minimize resource input and waste and emission production. The circular model adjusts our priorities and re-orients future infrastructure investments. In this context, we look back to nature to find the solutions we need to increase the resiliency of our societies, protect and restore the ecosystems, and maintain the necessary economic growth without further undermining the planet’s boundaries. Nature-based solutions (NBS) serve exactly this multi-factorial purpose due to their inherent ability to tackle climate change and to provide multiple ecosystems services and social benefits.
The NBS concept is based on biomimicry, i.e., the process where we learn from, are inspired by, and copy nature. NBS implementation requires a deep understanding of the natural environment and natural processes to harness the power of ecosystems and the sophistication of nature as infrastructure. NBS utilize complex natural processes, e.g., the ability to store carbon and regulate water flow, representing a key factor for well-being, life quality, prosperity, biodiversity, green growth, and social, economic and environmental sustainability. As the International Ecological Engineering Society mentions in their manifesto “systems thinking is the first critical step towards the development of new holistic and interdisciplinary engineering solutions at all scales. An ecology-inspired approach to engineering provides answers to these challenges. We view nature as part, not only of future solutions, but also of the design process itself”.
Nature-based solutions are of particular importance for water efficiency and the protection and restoration of aquatic ecosystems
According to the European Commission, there are four key areas for NBS implementation: (i) supporting sustainable urbanization to stimulate economic growth and enhance human well-being, (ii) restoring degraded ecosystems by improving their resilience and increasing the ecosystem services, (iii) climate change adaptation and mitigation, and (iv) improving risk management and resilience. As water is at the centre of climate change impacts, NBS are of particular importance for improved water efficiency and the protection and restoration of aquatic ecosystems. Blue/green space in the urban environment can reduce heat stress and flooding intensity. Wetlands provide multiple ecosystem services, such as flood protection, fisheries habitat, and water purification. NBS can change the way we manage our water resources, supporting the transition to sustainable and circular sanitation. Combined sewer overflow, i.e., municipal wastewater, urban runoff, and stormwater in the same pipe is collected towards an end-of-pipe centralized wastewater treatment plant. This often results in overloaded treatment plants and flood incidents in urban areas or further re-contamination of surface water bodies. Here, constructed wetlands bring new alternatives for decentralized and sustainable urban water and wastewater management by providing effective sanitation and pollution load reduction, while creating green spaces and reducing the carbon footprint.
As the global urban population continues to rise, there are multiple challenges such as resource depletion, climate change, and ecosystem degradation. A new holistic approach is required for the urban transition to a circular society, where resources are kept and reused within the city. NBS can fulfil these expectations and provide additional multifunctional benefits for the urban environment.