Nature-based solutions are emerging on the political agenda, not only as a potential climate adaptation strategy, but also as a popular means to build urban resilience, while tackling the multiple sustainability challenges cities are facing. For instance, open storm water management systems including sank parks, trees, rain gardens, open canals, permeable surfaces, and green roofs can reduce and manage flooding, and at the same time, can limit heat stress, as well as provide recreational spaces for different societal groups. This in turn can secure improved health outcomes, and can eventually reduce health costs for society. The example of storm water management shows that multiple benefits and multiple functions are the key value of nature-based solutions. Yet despite the recognized benefits and functions, the use of nature-based solutions remains marginal and green infrastructure continue to dominate urban development. In order to break this gray dominance, new approaches are needed for the development, implementation, and mainstreaming of nature-based solutions. Our work on nature-based solutions in the nature ration project shows pieces of evidence of innovative governance types and forms, innovative financial arrangements, noble business models, new institutional settings, and combinations of these. These examples all hold the potential for mainstreaming nature-based solutions within urban planning, policy, and development across the globe. But any innovation is a journey, from the initial idea all the way to its broader uptake within policy, industry, and society at large. Along this journey, it is critical to understand how innovation is supported through different governance strategies, institutional settings, and financial arrangements. It is also important to see what the enabling conditions and driving forces are for nature-based innovations in the context of urban sustainability transitions. But wait a minute, what do we actually mean by innovations? Do we mean new ideas, creative thoughts, new imaginations, new forms of devices or new methods? Or application of better solutions that meet new requirements, un-articulated or existing market needs, or something original and more effective and as a consequence, new that breaks into the market or society? No matter the definition, the literature agrees on at least one important thing. Innovations evolve in systems to make a meaningful impact in the market or society. Successful nature-based innovations in the context of urban sustainability transitions rely on a system, a system which can be broadly defined as a set of elements or parts that is coherently organized and interconnected in a pattern or structure that produces a characteristic set of behaviors, often classified as its function or purpose. A successful nature-based innovation relies on a system. It consists of actor networks, institutions, and infrastructure. A system that with all of its interconnected parts supports the development and diffusion of nature-based solutions. To better understand the key components of the emergence of nature-based innovations, we will first look into the different types of innovations. Then I will introduce you to the nature-based innovation system framework. Both the innovation typology and this innovation system framework have been developed by researchers in the nature mission project. Now let us first see what types of nature-based innovations are out there. We can differentiate among four main types: ecological or physical, social, technological, and system innovations. Ecological innovations are concerned with the creation of new green or blue natural spaces, the management of existing spaces, and the restoration of ecosystems and their functionality. The restoration of the Isar river in Munich, Germany is a good example where the removal of concrete along the river has increased accessibility and water-related recreational activities for different social groups, as well as enhanced biodiversity along the river. The second type is social innovations, and it refers to a new or significant changes in public policy or cultural frameworks, governance or economic arrangements, or methods for generating knowledge about nature in the city. A good example is the digital tree map, the so-called Urban Forest Visual developed by the city of Melbourne, Australia, which monitors the city's tree stock, while also engaging with citizen science. The third category of innovations is technological innovations. This includes product, process, and infrastructure innovations. The biodiversity project in Malmo, Sweden is an example for product and process innovation. In this project, multi-disciplinary actor groups developed a more bio-diverse and attractive low-maintenance intensive green roof by introducing new processes and new plant species as an alternative to the traditional moss roots. Last but not least, we have system innovations. System innovations lead to systemic changes, and can enable ecological, social, and technological innovations, as well as the interaction in between them. For example, developing a new master plan for large-scale transformation of urban neighborhoods that integrates multi-functional nature-based solutions will require major changes. Not only in ecological and technological innovation, but also changes to municipal working practices and organizational structures.
