NbS Triple Win Toolkit: Economics and Finance 53 Introduction Since the monetised value of ecosystem services across the globe was first highlighted in 199747, the economic case for restoration and considering ecosystem services in project and policy appraisal has been raised in numerous studies. Investing in the restoration or protection of nature has historically been viewed as being poor value for money since public benefits which are not typically or easily monetised in markets (e.g. ecosystem services) are not ordinarily included in conventional cost-benefit analyses and project appraisals48. By including a very broad range of benefits, these studies demonstrate that there is a strong economic case for investment in nature when incorporating both market and non-market benefits. Despite the fact that the proposed economic case for nature is often referenced as strong, there is a significant funding gap for adaptation and NbS. In its Adaptation Gap Report 2020, the United Nations Environment Programme (UNEP) identified adaptation investment needs of more than $140 billion (USD) per year by 203049. The Climate Policy Initiative (CPI) estimates that only $30 billion (USD) per year in mostly public funding was spent on adaptation in 201850, and another report estimates a current biodiversity conservation financing gapof between $598 billion (USD)and $824 billion (USD) per year51. The financing shortfall contrasts with the Paris agreement commitments: 62% of Nationally Determined Contributions (NDCs) include NbS as adaptation actions, and 63% declare protection of ecosystems and/or biodiversity as an intended outcome for adaptation projects and planning6. Given the importance of public funds for NbS and the current funding gap, it is important to understand what barriers are stopping additional finance from entering ODA countries for NbS projects. This chapter presents the evidence base for the economic case for investment in nature and recommendations to address the challenges around comparing the wide range of qualitative benefits which NbS deliver. The evidence represents both large-scale modelling studiesas well as economic analysis presented for individual NbS casestudies for six intervention types cross referenced with the casestudy database. Key barriers to increased private investment inNbS, as well as solutions and financial models which may helpbridge significant funding gaps, are also presented. Analytical approach The approach to analysing the cost-effectiveness and value for money of NbS considered both global-scale grey and published literature, as well as local-level NbS case studies and research projects. There have been numerous large-scale global analyses over the past two decades which have evaluated the economic case for nature47,48. These studies often include a broad range of public benefits, highlighting the monetary value of ecosystem services and the benefits from nature not ordinarily captured in market transactions48. These are used to promote and compare the potential of NbS in different biomes across the globe. In comparison, local NbS projects and research provide evidence ofthe effectiveness of a given intervention in a specific location, ecosystem or geography on-the-ground. The review of NbS case studies anddatabases included selection criteria for evaluation of costs and benefits (see Methods). The data upon which case study analyses are generally based are either locally generated or observed or else modelled based on local conditions (e.g. local agricultural yields,market prices). These studies are examples of either local NbS projects which already been started, undertaken or completed, or they are published research into the effectiveness of a given intervention in