NbS Triple Win Toolkit: Economics and Finance 52 For NbS projects which deliver monetisable benefits, benefit-cost ratios or cost-effectiveness metrics are useful tools to assess value for money. It is critical to continue undertaking these types of analyses to increase the evidence base and build the business and economic case for NbS investment by the public sector, especially given the wide range of co-benefits for biodiversity, climate and people. Additionally, such metrics help overcome an important information barrier to incentivising private sector finance by providing concise evidence about the financial returns available from NbS and revenue-generating activities. However, such tools often do not reflect the many benefits arising from the triple win which are still very difficult to monetise credibly. Given the importance of local impacts, such metrics are still used in a way which obscures who receives which benefits, who incurs which costs, where and when the benefits are realised, and elevates the relative attractiveness of NbS projects which generate benefits which aremore easily monetisable – often those which reduce future GHG emissions or protect economic assets. Since the Green Book recommends that optimising value for moneyis a case of balancing costs, benefits, risks, and unmonetisablefactors, more work needs to be undertaken to a) rigorously assessand document and the qualitative but strategically significant objectives across ecosystems and intervention-types, b) fund ex-post economic assessments which test key assumptions made at the project proposal stage, and c) continue attempts to monetise to other significant benefits, including biodiversity, capacity building and resilience,which are often treated as co-benefits rather than the principal objectives of NbS projects. Executive Summary NbS projects are characterised by the multiple benefits they can achieve across the triple win objectives, many of which are difficult to monetise credibly but are critical for the livelihoods of local communities.As recommended in the Principles and Implementation Guidance, parity must be given to each of the three strategic objectives withinthe triple win. Focusing the business and economic case on only those benefits which generate cash or can be monetised risks relegatingthe importance of poverty reduction and biodiversity benefits. Benefit-cost ratios and cost-effectiveness estimates vary between geographies, ecosystems and intervention types. Most of the issues which NbS seek to address (with the exception of climate change mitigation) are locally specific, so interventions should be tailored to biogeography, socioeconomics, or political systems. Though the evidence base is also varied, there is stronger evidence for the effectiveness of ecosystem-based protection of coastlines through EbA or mangrove restoration, although there are still few on-the-ground ex-post analyses. Reforestation and avoided deforestation may also provide promising, cost-effective options for maximising climate change mitigation in specific parts of the world. This may require converting or restoring land (or avoiding the conversion of land) previously developed or cleared for high value use such as agriculture. In these instances, opportunity costs may be higher to compensate local landowners, driving up the cost of NbS. Across all NbS projects and global studies, the total benefits arising from NbS are likely understated since many of the co-benefits and capacity building activities are not routinely monetised and included in project appraisals.