NbS Triple Win Toolkit: Economics and Finance 80 both biodiversity and poverty are typically characterised by: Spatial definition. Biodiversity is heavily dependent on the ecosystems, or sets of interconnected ecosystems, in adelineated spatial area. What constitutes poverty varieslargely across a given catchment area. Multiple facets. Biodiversity can be measured in numerous ways depending on local context, the strategic case and available data(see Biodiversity Indicators in Context). Poverty is not simply characterised by income below a given threshold. Rather, it incorporates social protection, rights to and dependency upon economic and natural resources, access to basic services,ownership and control over land and assets, and financial services75. Non-market goods. In particular, the benefits and associated values of biodiversity and ecosystems are not typically reflected in market goods120. Similarly, benefits such as health are not typically captured directly by traditional markets. Since qualitative benefits are significant in the context of a triple win NbS, it is difficult to conclude meaningfully on the overall cost-effectiveness of NbS since the value for money varies with context and is likely understated if reliance is placed on monetised benefits. Attempts have been made to value broader, difficult-to-quantify concepts such as climate resilience and upskilling from capacity building. A recent review the evidence base of various intangible aspects of climate resilient development suggests that benefitsaccrued are expected to outweigh the costs by a factor of 2 andcan reach as high as £50 (GBP) to every £1 (GBP) invested,although confidence in such findings is typically low as resiliencyis particularly context specific76. Cost Historically it has been difficult to estimate costs globally as there are no common standards for such reporting48. With no common standard, it is difficult to compare NbS with non-NbS projects. The challenges arising from cost data inconsistencies are well documented in the literature100,122. Of the most important cost categories is opportunitycost since it is highly-site specific, very variable (even negative) andis often the cost category which represents the highest proportionof costs for projects which seek to avoid deforestation122. Different studies take different approaches to estimating opportunity costs. Large-scale studies which focus on available average or cost estimates to approximate opportunity cost may overstate the economic case of on-the-ground NbS projects where there are high-value alternative land uses or large local institutional barriers to setting up NbS projects48,65. Not only does the lack of information make it difficult to ascertain the true costs of NbS projects, but also it makes comparison between NbS projects (with differing activities, focal areas, interventions) and between NbS and non-NbS projects nearly impossible. Furthermore, this level of disaggregation makes it difficult to understand the key drivers of cost, when these costs are incurred, to whom they accrue and therefore the barriers to implementation and success of NbS projects. Ignoring or using simplified metrics to capture opportunity cost risks incorrectly addressing the principal drivers of environmental degradation by private landowners and investment by the private sector. It may also encourage inappropriate project designs whichdo not engage – economically or pragmatically – with understanding why local land use changes (and, by extension, climate change andthe reduction in biodiversity) occur in a given region or country.In the absence of this information however, such models would