Nature-based solutions (NBS) offer multiple solutions to urban challenges simultaneously, but realising funding for NBS remains a challenge. When the concept of NBS for societal challenges was first defined by the EC in 2017, financing was recognised as one of the major challenges to its mainstreaming. The complexity of NBS finance has its origin in the multiple benefits/stakeholders involved, which obscures the argument for both public and private sector investment. Since 2017, subsequent waves of EU research- and innovation-funded projects have substantially contributed to the knowledge base of funding and business models for NBS, particularly in the urban context. Collaborating and sharing knowledge through an EU Task Force, this first set of EU projects laid important knowledge foundations, reviewing existing literature, and compiling empirical evidence of different financing approaches and the business models that underpinned them. The second set of EU innovation actions advanced this knowledge base, developing and testing new implementation models, business model tools, and approaches. This paper presents the findings of these projects from a business model perspective to improve our understanding of the value propositions of NBS to support their mainstreaming.

This paper critically analyses the methodologies that can be adopted to value ecosystem services (ESs) at the urban level through a literature review. While literature on ES valuation has grown in recent years, its application to urban contexts is still limited. Twenty-five papers, which include 29 different case studies, carry out an economic valuation and have undergone an in-depth analysis. The papers have been selected out of 80 papers detected through keywords. Six different valuation methodologies have been employed in the case studies. The most common ESs valued at the urban level are air quality regulation, local climate regulation, carbon sequestration and storage, and aesthetic appreciation and inspiration for culture, art, and design. The methodologies recur with different frequencies in the valuation of ESs at the urban level. Choice modeling and contingent valuation methodologies are used to value a variety of ESs, including regulating, cultural, and supporting services. Other methodologies are used to value only specific ESs. The replacement cost and damage cost avoided methodologies are used for the assessment of regulation services only; the travel cost method and contingent valuation are used for cultural services only. The results indicate that the considered valuation methodologies show different levels of appropriateness with respect to specific ES categories. Therefore, there is a need to expand the application of valuation methodologies to capture the value of all ESs provided by natural resources, in order to protect and enhance them.

Nature-Based Solutions (NBSs) are increasingly financed in urban, regional, and national contexts due to their proven capacity to reduce climate risks and deliver multiple co-benefits. Several challenges affect the successful implementation and long-term maintenance of NBSs, especially in climate-sensitive and fragile urban territories (e.g., the Mediterranean basin), characterized by intense urbanization, environmental vulnerability, socio-economic disparities, and fragmented governance. Key barriers include difficulties in economically evaluating NBS benefits, uncertainty about their effectiveness under changing climate conditions, and implementing multi-functional projects with an interdisciplinary perspective. To address these challenges, a participatory process was conducted involving three thematic working tables focused on the following: (1) economic evaluation, (2) co-design for climate resilience, and (3) multi-functionality and disciplinary integration. All groups applied a shared SWOT (Strengths, Weaknesses, Opportunities, Threats) methodology structured in four phases: (i) individual reflection and collective brainstorming; (ii) collaborative SWOT matrix development; (iii) roadmaps formulation; and (iv) narrative synthesis and submission. Grounded in their knowledge and practical experiences, stakeholders identified operational barriers and strategic advantages to identify research gaps and designing adaptive, inclusive, and context-sensitive NBS roadmaps. Although the stakeholders were primarily based in Northern Italy, they also brought national and international experience, making the findings relevant and transferable to other urban areas in the Mediterranean and Europe, facing similar socio-environmental challenges and governance issues. Thus, the study supports more effective planning and governance in comparable contexts, emphasizing integrated and flexible approaches to address urban fragility and optimize projects governance and management.